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Cited by 405Dementia and Cognitive Impairment ResearchMemory Processes and InfluencesNeurobiology of Language and Bilingualism

Considering the role of semantic memory in episodic future thinking: evidence from semantic dementia

Open access
Irish, Muireann, Addis, Donna Rose, Hodges, John R., Piguet, Olivier·2012·Brain
DOI 10.1093/brain/aws119
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Abstract

Semantic dementia is a progressive neurodegenerative condition characterized by the profound and amodal loss of semantic memory in the context of relatively preserved episodic memory. In contrast, patients with Alzheimer's disease typically display impairments in episodic memory, but with semantic deficits of a much lesser magnitude than in semantic dementia. Our understanding of episodic memory retrieval in these cohorts has greatly increased over the last decade, however, we know relatively little regarding the ability of these patients to imagine and describe possible future events, and whether episodic future thinking is mediated by divergent neural substrates contingent on dementia subtype. Here, we explored episodic future thinking in patients with semantic dementia (n=11) and Alzheimer's disease (n=11), in comparison with healthy control participants (n=10). Participants completed a battery of tests designed to probe episodic and semantic thinking across past and future conditions, as well as standardized tests of episodic and semantic memory. Further, all participants underwent magnetic resonance imaging. Despite their relatively intact episodic retrieval for recent past events, the semantic dementia cohort showed significant impairments for episodic future thinking. In contrast, the group with Alzheimer's disease showed parallel deficits across past and future episodic conditions. Voxel-based morphometry analyses confirmed that atrophy in the left inferior temporal gyrus and bilateral temporal poles, regions strongly implicated in semantic memory, correlated significantly with deficits in episodic future thinking in semantic dementia. Conversely, episodic future thinking performance in Alzheimer's disease correlated with atrophy in regions associated with episodic memory, namely the posterior cingulate, parahippocampal gyrus and frontal pole. These distinct neuroanatomical substrates contingent on dementia group were further qualified by correlational analyses that confirmed the relation between semantic memory deficits and episodic future thinking in semantic dementia, in contrast with the role of episodic memory deficits and episodic future thinking in Alzheimer's disease. Our findings demonstrate that semantic knowledge is critical for the construction of novel future events, providing the necessary scaffolding into which episodic details can be integrated. Further research is necessary to elucidate the precise contribution of semantic memory to future thinking, and to explore how deficits in self-projection manifest on behavioural and social levels in different dementia subtypes.

AI snapshot

Written from the paper’s full text.

TL;DR

In semantic dementia (SD), episodic future thinking was severely impaired despite relatively preserved recent past episodic memory, whereas Alzheimer's disease (AD) showed parallel past and future episodic deficits. The findings suggest semantic memory provides critical scaffolding for constructing novel future events, with distinct neural correlates in SD versus AD.

Key findings

  • In the past episodic condition, SD patients scored at control levels (P = 0.183) and recalled significantly more internal details than AD patients (P = 0.029, mean difference = 13.7, 95% CI 1.2–26.3). For future internal details, both patient groups were equally impaired relative to controls (SD: mean difference = 19.7, 95% CI 9.5–30.0; AD: mean difference = 18.2, 95% CI 8.7–27.7).
  • Controls and SD patients showed a past > future effect (controls: P = 0.001, mean difference = 9.8, 95% CI 4.3–15.4; SD: P < 0.0001, mean difference = 18.8, 95% CI 13.6–23.9), whereas AD patients performed equally poorly in past and future conditions (P = 0.154).
  • Both patient groups were impaired on semantic past and future thinking, but SD deficits were more pronounced than AD across semantic past (P = 0.028) and future (P = 0.008) conditions.
  • VBM showed episodic future thinking in SD correlated with atrophy in the left inferior temporal gyrus and right temporal pole, while in AD it correlated with posterior cingulate, parahippocampal gyrus, and frontal pole. SD patients also recast prior events in 80% of future episodic trials versus 67% in AD.

Methods

  • Participants: 22 patients with dementia (SD = 11; AD = 11) and 10 education-matched healthy controls recruited through FRONTIER at Neuroscience Research Australia, Sydney; all underwent structural MRI.
  • Tasks: past and future autobiographical event construction based on Addis et al. (2008), with three past and three future trials using cue words and images, scored with the Autobiographical Interview for internal/external details; semantic past/future thinking assessed with the “Known” subscale of the Memory and Temporal Experience questionnaire (Klein et al., 2002), scaled to a maximum of 10 points.
  • Analyses: repeated-measures ANOVA with Sidak post hoc tests, chi-squared tests, and one-tailed Pearson correlations; VBM using FSL-VBM with permutation-based non-parametric testing (5000 permutations), age as a covariate, P < 0.001 uncorrected, and clusters of at least 80 contiguous voxels.

Limitations

  • The paper states that further research is necessary to elucidate the precise contribution of semantic memory to future thinking and to explore how self-projection deficits manifest behaviourally and socially in different dementia subtypes.
  • Evident from the text: small samples (SD n = 11, AD n = 11, controls n = 10), groups not matched for age (controls on average 7.1 years older than SD patients) and uneven sex distribution (male:female ratio higher in patient groups).
  • Evident from the text: VBM results are uncorrected for multiple comparisons at P < 0.001, and the design is cross-sectional and correlational, so causal direction cannot be established.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1093/brain/aws119

Cites

98 of 98 references verified0 citation errors · 0 not checkable

Statistics

Claims the paper makes

0 of 83 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    Atrophy in the left inferior temporal gyrus and bilateral temporal poles correlated significantly with deficits in episodic future thinking in semantic dementia.

    “Voxel-based morphometry analyses confirmed that atrophy in the left inferior temporal gyrus and bilateral temporal poles, regions strongly implicated in semantic memory, correlated significantly with deficits in episodic future thinking in semantic dementia.”
    Quote in the paperSubstantial claim
  • Findingown data

    Episodic future thinking performance in Alzheimer's disease correlated with atrophy in the posterior cingulate, parahippocampal gyrus and frontal pole.

    “Conversely, episodic future thinking performance in Alzheimer's disease correlated with atrophy in regions associated with episodic memory, namely the posterior cingulate, parahippocampal gyrus and frontal pole.”
    Quote in the paperSubstantial claim
  • Findingown data

    The group with Alzheimer's disease showed parallel deficits across past and future episodic conditions.

    “In contrast, the group with Alzheimer's disease showed parallel deficits across past and future episodic conditions.”
    Quote in the paperSubstantial claim
  • Findingown data

    Differential patterns emerged for the generation of past and future internal details in the groups with semantic dementia and Alzheimer's disease.

    “The key result, illustrated in Fig. 1, was that differential patterns emerged for the generation of past and future internal details in the groups with semantic dementia and Alzheimer's disease.”
    Quote in the paperSubstantial claim
  • Findingown data

    The group effect was qualified by a significant condition × group interaction.

    “This group effect was qualified by a significant condition  group interaction [F(2,28) = 9.847, P = 0.001].”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim. 37
  • May combine two claims. 42
  • The quote only partly states this claim. 1

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingown data

    The groups were matched for years of education but not age; controls were on average 7.1 years older than patients with semantic dementia.

    “The groups were matched for years of education but not age, controls being on average 7.1 years older than patients with semantic dementia [F(2, 29) = 4.122, P = 0.027].”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    There was an overall main effect of group, with controls providing more internal details than the patient groups.

    “An overall main effect of group was found [F(2,28) = 13.182,P 5 0.0001], with controls providing more internal details than the patient groups.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Correlational analyses confirmed the relation between semantic memory deficits and episodic future thinking in semantic dementia, in contrast with the role of episodic memory deficits and episodic future thinking in Alzheimer's disease.

    “These distinct neuroanatomical substrates contingent on dementia group were further qualified by correlational analyses that confirmed the relation between semantic memory deficits and episodic future thinking in semantic dementia, in contrast with the role of episodic memory deficits and episodic future thinking in Alzheimer's disease.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    Sex was not evenly distributed between the groups, with a higher male:female ratio in the patient groups compared with the control group.

    “Sex was not evenly distributed between the groups, as the male:female ratio was higher in the patient groups compared with the control group [ 2 (2) = 7.536, P = 0.023].”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    In semantic dementia, disproportionate deficits on semantic tasks (Naming and Comprehension) were evident, in the context of relatively preserved executive function.

    “In semantic dementia, disproportionate deficits on semantic tasks (Naming and Comprehension) were evident, in the context of relatively preserved executive function ( Trails”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Despite relatively intact episodic retrieval for recent past events, the semantic dementia cohort showed significant impairments for episodic future thinking.

    “Despite their relatively intact episodic retrieval for recent past events, the semantic dementia cohort showed significant impairments for episodic future thinking.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    There were no significant differences for disease duration or general cognitive functioning between the patient groups.

    “A univariate ANOVA revealed no significant differences for disease duration or general cognitive functioning between the patient groups.”
    Quote in the paperSubstantial claim

  • The quote only partly states this claim.

    Findingown data

    Patients with Alzheimer's disease showed impairments in semantic past retrieval compared with controls (P 5 0.0001, mean difference = 4.0, 95% CI 1.8-6.2).

    “Patients with Alzheimer's disease showed impairments across past (P 5 0.0001, mean difference = 4.0, 95% CI 1.8-6.2)”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    Verbal output did not differ significantly between the groups.

    “indicating that verbal output did not differ significantly between the groups”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Episodic future thinking in semantic dementia was related to atrophy in the left anterior temporal lobe, whereas atrophy in the left posterior cingulate, right parahippocampal gyrus and left frontal pole significantly predicted episodic future thinking deficits in Alzheimer's disease.

    “Episodic future thinking in semantic dementia was related to atrophy in the left anterior temporal lobe, whereas atrophy in the left posterior cingulate, right parahippocampal gyrus and left frontal pole significantly predicted episodic future thinking deficits in Alzheimer's disease.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In Alzheimer's disease, episodic future thinking correlated with the retrieval of past episodic internal details and performance on a standardized test of episodic memory (Doors Part A), but with none of the measures of semantic knowledge.

    “In Alzheimer's disease, episodic future thinking correlated with the retrieval of past episodic internal details and performance on a standardized test of episodic memory (Doors Part A), but with none of the measures of semantic knowledge.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Compared with controls, patients with semantic dementia showed significant atrophy in the anterior temporal lobes bilaterally, with greatest atrophy present in the left hemisphere (Table 3 and Fig. 3).

    “Compared with controls, patients with semantic dementia showed significant atrophy in the anterior temporal lobes bilaterally, with greatest atrophy present in the left hemisphere (Table 3 and Fig. 3).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In semantic dementia, episodic future thinking was related to retrieval of past episodic and semantic information, generation of future semantic information and a measure of semantic knowledge (naming), but not with a measure of non-verbal episodic memory.

    “In semantic dementia, episodic future thinking was related to retrieval of past episodic and semantic information, generation of future semantic information and a measure of semantic knowledge (naming), but not with a measure of non-verbal episodic memory.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Left temporal lobe atrophy also significantly correlated with semantic future thinking deficits in semantic dementia, pointing to overlap in the neural substrates mediating these types of future-oriented thought.

    “Left temporal lobe atrophy also significantly correlated with semantic future thinking deficits in semantic dementia, pointing to overlap in the neural substrates mediating these types of future-oriented thought.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    Sex and age did not exert a significant effect for any of the experimental variables.

    “Sex and age did not exert a significant effect for any of the experimental variables.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    In contrast, widespread patterns of atrophy were evident in the group with Alzheimer's disease relative to controls, involving the medial and lateral temporal lobes including the left hippocampus and insular cortex, bilateral frontal poles and posterior brain regions, notably the angular gyrus bilaterally.

    “In contrast, widespread patterns of atrophy were evident in the group with Alzheimer's disease relative to controls, involving the medial and lateral temporal lobes including the left hippocampus and insular cortex, bilateral frontal poles and posterior brain regions, notably the angular gyrus bilaterally.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    In semantic dementia, atrophy in the bilateral anterior temporal lobes, including the anterior inferior temporal gyrus and temporal pole, correlated with episodic future thinking performance, whereas, in Alzheimer's disease, the posterior cingulate, posterior parahippocampal gyrus and frontal pole correlated with episodic future thinking capacity.

    “In semantic dementia, atrophy in the bilateral anterior temporal lobes, including the anterior inferior temporal gyrus and temporal pole, correlated with episodic future thinking performance, whereas, in Alzheimer's disease, the posterior cingulate, posterior parahippocampal gyrus and frontal pole correlated with episodic future thinking capacity.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S1 (asserted), S3 (load-bearing), S4 (based).

    Findingnone given

    Addenbrooke's Cognitive Examination-Revised scores did not differ between semantic dementia and Alzheimer's disease patients.

    “semantic dementia = Alzheimer's disease”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    Alzheimer's disease patients had longer Trail Making Test Part B-A times than controls.

    “Trail Making Test Part B-A (s) | 59.7 (32.0) | 119.2 (67.8) | 49.7 (17.4) | * | Alzheimer's disease 5 controls”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    Alzheimer's disease patients had lower Rey Auditory Verbal Learning Task scores than controls.

    “Rey Auditory Verbal Learning | NA | 2.4 (2.8) | 10.6 (2.1) | *** | Alzheimer's disease 5 controls”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    Alzheimer's disease patients had lower Rey Complex Figure 3 min recall scores than controls.

    “Rey Complex Figure, 3 min | 15.7 (6.3) | 4.7 (4.7) | 14.3 (6.0) | ** | Alzheimer's disease 5 controls”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    Semantic dementia patients had lower Naming scores than Alzheimer's disease patients.

    “semantic dementia 5 Alzheimer's disease”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Although our semantic dementia cohort exhibited significant bilateral hippocampal atrophy, anterior temporal lobe rather than medial temporal structures were found to correlate with their episodic future thinking performance.

    “Although our semantic dementia cohort exhibited significant bilateral hippocampal atrophy, anterior temporal lobe rather than medial temporal structures were found to correlate with their episodic future thinking performance.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    VBM analyses showed brain areas in which grey matter intensity correlates significantly with episodic future thinking in semantic dementia and control participants, and in Alzheimer's disease and control participants.

    “VBM analyses showing brain areas in which grey matter intensity correlates significantly with episodic future thinking in SD and Control participants (red), and in Alzheimer's disease and Control participants (green).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    Alzheimer's disease patients had lower Doors Part A scores than controls.

    “Doors Part A (12) | 8.4 (2.7) | 7.4 (2.4) | 11.0 (1.2) | ** | Alzheimer's disease 5 controls”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingcitation

    The relationship between atrophy in the posterior cingulate and episodic future thinking performance in Alzheimer's disease is significant, adding to converging evidence that views the posterior cingulate as critical in the genesis of declarative memory problems in this patient cohort.

    “The relationship between atrophy in the posterior cingulate and episodic future thinking performance in Alzheimer's disease is significant, adding to converging evidence that views the posterior cingulate as critical in the genesis of declarative memory problems in this patient cohort (Nestor et al., 2006;Irish et al., 2011a).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Nestor et al., 2006 source

      Not checked in the free run.

    • cites Irish et al., 2011a

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    Alzheimer's disease patients had lower Rey Complex Figure 3 min recall scores than semantic dementia patients.

    “Alzheimer's disease 5 semantic dementia”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Our Alzheimer's disease group displayed a distinct pattern of atrophy that correlated with their episodic future thinking deficits, including atrophy in the posterior cingulate, parahippocampal gyrus and frontal pole.

    “Our Alzheimer's disease group displayed a distinct pattern of atrophy that correlated with their episodic future thinking deficits, including atrophy in the posterior cingulate, parahippocampal gyrus and frontal pole.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S1 (asserted), S3 (load-bearing).

    Findingown data

    Controls were older than patients with semantic dementia.

    “Age (years) | 62.1 (5.5) | 64.6 (6.1) | 69.2 (5.6) | * | Controls 4 semantic dementia”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    There is considerable overlap between episodic and semantic representations and a likely pivotal role of semantic memory in self-projective tasks.

    “The emerging evidence suggests considerable overlap between episodic and semantic representations and the likely pivotal role of semantic memory in self-projective tasks (Binder and Desai, 2011;Irish et al., 2012).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Binder and Desai, 2011 source

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    • cites Irish et al., 2012 source

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  • Classified as probably not a substantial claim. May combine two claims.

    Premisenone given

    Little is known about the ability of patients with semantic dementia and Alzheimer's disease to imagine and describe possible future events, and whether episodic future thinking is mediated by divergent neural substrates contingent on dementia subtype.

    “however, we know relatively little regarding the ability of these patients to imagine and describe possible future events, and whether episodic future thinking is mediated by divergent neural substrates contingent on dementia subtype.”
    • Also stated in: § Introduction · plain
      “Although significant advances have been made in understanding the component processes of this future-oriented system in healthy individuals (D' Argembeau et al., 2010;Addis et al., 2011), few corroborative human lesion studies exist.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites D' Argembeau et al., 2010

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    • cites Addis et al., 2011 source

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    Premisecitation

    Semantic dementia is a progressive neurodegenerative condition.

    “Semantic dementia is a progressive neurodegenerative condition characterized by the profound and amodal loss of semantic memory in the context of relatively preserved episodic memory.”
    • Also stated in: § Introduction · plain
      “It is a neurodegenerative brain disorder within the frontotemporal dementia spectrum (Neary et al., 1998;Gorno-Tempini et al., 2011)”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Neary et al., 1998 source

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    • cites Gorno-Tempini et al., 2011 source

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  • Classified as probably not a substantial claim.

    Study design and conductnone given

    Age was controlled for in all subsequent analyses.

    “Age was controlled for in all subsequent analyses.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Premisecitation

    Past autobiographical retrieval is crucial for the construction and elaboration of future events.

    “A central principle underlying current theories of episodic future thinking is that past autobiographical retrieval is crucial for the construction and elaboration of future events (Addis and Schacter, 2008;Szpunar and McDermott, 2008).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Addis and Schacter, 2008

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    • cites Szpunar and McDermott, 2008

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  • Classified as probably not a substantial claim.

    Interpretationreasoning

    Damage to the episodic memory system should impair the ability to imagine events in the future.

    “If episodic future thinking relies on the extraction and flexible recombination of episodic details from past events (Schacter and Addis, 2007a, b), it follows that damage to the episodic memory system should impair the ability to imagine events in the future.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Schacter and Addis, 2007a, b

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  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductcitation

    Healthy controls scored 0 on the Clinical Dementia Rating scale and 85 or above on the Addenbrooke's Cognitive Examination-Revised.

    “All controls scored 0 on the Clinical Dementia Rating scale (Morris, 1997), and 85 or above on the Addenbrooke's Cognitive Examination-Revised (Mioshi et al., 2006).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Morris, 1997 source

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    • cites Mioshi et al., 2006 source

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  • Classified as probably not a substantial claim.

    Study design and conductcitation

    The standardized scoring procedure of the Autobiographical Interview was used to score each event.

    “The standardized scoring procedure of the Autobiographical Interview (Levine et al., 2002) was used to score each event.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Levine et al., 2002 source

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    Study design and conductnone given

    All thresholds reported are uncorrected at the P 5 0.001 level.

    “All thresholds reported are uncorrected at the P 5 0.001 level.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    Diagnosis was established by consensus among a senior neurologist, neuropsychologist and occupational therapist based on extensive clinical investigations, cognitive assessment and evidence of atrophy on structural brain neuroimaging.

    “Diagnosis was established by consensus among a senior neurologist, neuropsychologist and occupational therapist based on extensive clinical investigations, cognitive assessment and evidence of atrophy on structural brain neuroimaging.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductown data

    Results were significant for P < 0.001, uncorrected for multiple comparisons, including age as a covariate.

    “Results were significant for P 5 0.001, uncorrected for multiple comparisons, including age as a covariate.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    These patterns of atrophy are consistent with previous reports in semantic dementia and in Alzheimer's disease.

    “These patterns of atrophy are consistent with previous reports in semantic dementia (Rosen et al., 2002;Mion et al., 2010) and in Alzheimer's disease (Karas et al., 2004;Dickerson et al., 2009).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites Rosen et al., 2002 source

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    • cites Mion et al., 2010 source

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    • cites Karas et al., 2004 source

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  • Classified as probably not a substantial claim.

    Study design and conductcitation

    The 'Known' (semantic) subscale of the Memory and Temporal experience questionnaire was used to probe past semantic retrieval and future semantic thinking.

    “The 'Known' (semantic) subscale of the Memory and Temporal experience questionnaire (Klein et al., 2002) was used to probe past semantic retrieval and future semantic thinking.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Klein et al., 2002 source

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  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    Correlations between episodic future thinking performance and grey matter intensity for key regions of interest were plotted to ensure that the data were normally distributed.

    “As a final check, the correlations between episodic future thinking performance and grey matter intensity for the key regions of interest were plotted to ensure that the data were normally distributed (Supplementary material).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    While divergent neural circuits underlie the capacity for episodic future thinking in semantic dementia and Alzheimer's disease, a common substrate for semantic future thinking is evident irrespective of dementia type.

    “Therefore, while divergent neural circuits underlie the capacity for episodic future thinking in semantic dementia and Alzheimer's disease, a common substrate for semantic future thinking is evident irrespective of dementia type.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    These findings relate to the underlying deficits characteristic of each patient group, and were attributable to specific patterns of neural atrophy as demonstrated by VBM analyses.

    “These findings relate to the underlying deficits characteristic of each patient group, and were attributable to specific patterns of neural atrophy as demonstrated by VBM analyses.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    Despite a relative preservation of recent episodic memory in semantic dementia, significant deficits in the construction of future episodes were evident.

    “Despite a relative preservation of recent episodic memory in semantic dementia, significant deficits in the construction of future episodes were evident.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductcitation

    All behavioural results were plotted to ensure that the distribution of scores was not bimodal.

    “Given the significant temporal lobe atrophy typically seen in semantic dementia (Mion et al., 2010), all behavioural results were plotted to ensure that the distribution of scores was not bimodal.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Mion et al., 2010 source

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  • May combine two claims.

    Interpretationcitation

    Our findings corroborate those from a recent study investigating the link between the self and autobiographical memory in semantic dementia across past, present and future contexts, which also suggests that episodic memory alone may not be sufficient for envisioning the future.

    “Our findings corroborate those from a recent study investigating the link between the self and autobiographical memory in semantic dementia across past, present and future contexts, which also suggests that episodic memory alone may not be sufficient for envisioning the future (Duval et al., 2012).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Duval et al., 2012 source

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  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Structures within the medial temporal lobe are clearly vital for the extraction of past episodic details, and possibly also their successful recombination into a novel and spatially coherent simulation.

    “Structures within the medial temporal lobe are clearly vital for the extraction of past episodic details, and possibly also their successful recombination into a novel and spatially coherent simulation (Hassabis et al., 2007a;Addis and Schacter, 2008).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Hassabis et al., 2007a

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    • cites Addis and Schacter, 2008

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  • May combine two claims.

    Interpretationcitation

    The demonstration that semantic memory contributes to the imagining of personal episodic future events, and future self-representations, represents an expansion to the current view of episodic future thinking which, to date, has focused primarily on the role of the medial temporal lobe and episodic memory.

    “The demonstration that semantic memory contributes to the imagining of personal episodic future events, and future selfrepresentations (Duval et al., 2012), represents an expansion to the current view of episodic future thinking which, to date, has focused primarily on the role of the medial temporal lobe and episodic memory (Schacter and Addis, 2007a, b;Race et al., 2011).”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Duval et al., 2012 source

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    • cites Schacter and Addis, 2007a, b

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    • cites Race et al., 2011 source

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  • May combine two claims.

    Interpretationown data

    In summary, the major finding of this study is that patients with semantic dementia exhibit profound deficits in the ability to imagine future events, despite a relative preservation of recent episodic memory.

    “In summary, the major finding of this study is that patients with semantic dementia exhibit profound deficits in the ability to imagine future events, despite a relative preservation of recent episodic memory.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    Though our findings in Alzheimer's disease reinforce current thinking that loss of episodic memory can disrupt episodic future thinking, they nevertheless challenge the view that episodic future thinking deficits in Alzheimer's disease can be explained by medial temporal lobe damage alone.

    “Importantly, though our findings in Alzheimer's disease reinforce current thinking that loss of episodic memory can disrupt episodic future thinking (Tulving, 1985;Klein et al., 2002;Hassabis et al., 2007b;Kwan et al., 2010;Race et al., 2011), they nevertheless challenge the view that episodic future thinking deficits in Alzheimer's disease can be explained by medial temporal lobe damage alone.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Tulving, 1985 source

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    • cites Klein et al., 2002 source

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    • cites Hassabis et al., 2007b

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  • May combine two claims.

    Interpretationown data

    Using semantic dementia as a lesion model for semantic memory illuminates the importance of conceptual knowledge in the construction of future scenarios, an ability previously posited to depend exclusively on the integrity of the episodic memory system.

    “Using semantic dementia as a lesion model for semantic memory illuminates the importance of conceptual knowledge in the construction of future scenarios, an ability previously posited to depend exclusively on the integrity of the episodic memory system.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S2 (checkable). May combine two claims.

    Premisecitation

    Episodic memory represents unique occurrences, located within a specific spatiotemporal framework, bearing emotional and self-referential connotations, and is typically imbued with autonoetic consciousness.

    “Episodic memory represents unique occurrences, located within a specific spatiotemporal framework, bearing emotional and self-referential connotations (Conway, 2009), and is typically imbued with autonoetic consciousness (Tulving, 1985;Irish et al., 2008).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites Conway, 2009 source

      Not checked in the free run.

    • cites Tulving, 1985 source

      Not checked in the free run.

    • cites Irish et al., 2008 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    All clusters reported t > 3.97.

    “All clusters reported t 4 3.97.”
    • Also stated in: § Discussion · plain
      “All clusters reported t 4 3.97.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    In a recent study in healthy individuals, activity in the medial prefrontal cortex and posterior cingulate correlated significantly with participants' ratings of personal significance and affect.

    “This idea is further qualified by a recent study in healthy individuals, in which activity in the medial prefrontal cortex and posterior cingulate correlated significantly with participants' ratings of personal significance and affect (Andrews-Hanna et al., 2010).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Andrews-Hanna et al., 2010 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    This becomes particularly important given the pervasive lack of empathy commonly reported by caregivers of patients with semantic dementia.

    “This becomes particularly important given the pervasive lack of empathy commonly reported by caregivers of patients with semantic dementia (Mychack et al., 2001;Rankin et al., 2006).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Mychack et al., 2001 source

      Not checked in the free run.

    • cites Rankin et al., 2006 source

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    By studying two dementia syndromes characterized by differential impairments in episodic and semantic memory, our findings indicate that if either episodic or semantic memory-and regions supporting these functions-are sufficiently compromised, the construction of future scenarios will be impaired.

    “By studying two dementia syndromes characterized by differential impairments in episodic and semantic memory, our findings indicate that if either episodic or semantic memory-and regions supporting these functions-are sufficiently compromised, the construction of future scenarios will be impaired.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Self-projection underlies many cognitive abilities that are essential for successful human interactions.

    “Self-projection underlies many cognitive abilities that are essential for successful human interactions (Buckner and Carroll, 2007).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Buckner and Carroll, 2007 source

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    Taken together, these findings suggest that the characteristic patterns of atrophy in Alzheimer's disease disrupt the self-referential or autonoetic aspect of episodic thinking as has been demonstrated for retrieval of autobiographical events from across the lifespan.

    “Taken together, these findings suggest that the characteristic patterns of atrophy in Alzheimer's disease disrupt the self-referential or autonoetic aspect of episodic thinking as has been demonstrated for retrieval of autobiographical events from across the lifespan (Irish et al., 2011b).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Irish et al., 2011b

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    The results from the group with semantic dementia stand in contrast to those observed in Alzheimer's disease, whereby parallel deficits across past and future episodic conditions are evident.

    “The results from the group with semantic dementia stand in contrast to those observed in Alzheimer's disease, whereby parallel deficits across past and future episodic conditions are evident.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    In semantic dementia, recasting of prior events occurs in the face of an inability to generate the conceptual framework for a novel future event, despite largely preserved episodic memory retrieval.

    “We suggest that in semantic dementia, recasting of prior events occurs in the face of an inability to generate the conceptual framework for a novel future event, despite largely preserved episodic memory retrieval.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    These regions have been linked previously with episodic imagery, contextual detail and scene construction processes important to both past and future events.

    “Notably, these regions have been linked previously with episodic imagery, contextual detail and scene construction processes important to both past and future events (Fletcher et al., 1995;Bar and Aminoff, 2003;Okuda et al., 2003;Hassabis and Maguire, 2007;Hassabis et al., 2007a;Szpunar et al., 2009;Andrews-Hanna et al., 2010).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites Fletcher et al., 1995 source

      Not checked in the free run.

    • cites Bar and Aminoff, 2003

      Not checked in the free run.

    • cites Okuda et al., 2003 source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    Additional involvement of midline cortical regions such as the posterior cingulate, and the prefrontal cortex in Alzheimer's disease, points to the disruption of self-referential or autonoetic thought in this cohort, whereas erosion of the semantic memory system appears to be the primary contributing mechanism to future thinking deficits in semantic dementia.

    “Additional involvement of midline cortical regions such as the posterior cingulate, and the prefrontal cortex in Alzheimer's disease, points to the disruption of self-referential or autonoetic thought in this cohort, whereas erosion of the semantic memory system appears to be the primary contributing mechanism to future thinking deficits in semantic dementia.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    In Duval et al. (2012), recall of past self-representations was preserved in semantic dementia, but patients demonstrated significant impairments when thinking about their possible future selves.

    “Whereas recall of past self-representations was preserved, patients with semantic dementia demonstrated significant impairments when thinking about their possible future selves.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Duval et al., 2012 source

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    The profound deficits in simulating future events exhibited by patients with semantic dementia, despite a relative preservation of past episodic memory, suggest that other forms of self-projection, such as theory of mind, empathy and moral reasoning, may also be compromised.

    “The profound deficits in simulating future events exhibited by patients with semantic dementia, despite a relative preservation of past episodic memory, suggest that other forms of self-projection, such as theory of mind, empathy and moral reasoning (Spreng et al., 2009), may also be compromised.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Spreng et al., 2009 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    In the VBM analysis, coloured voxels show regions that were significant with P < 0.001 uncorrected with a cluster threshold of 80 contiguous voxels.

    “Coloured voxels show regions that were significant in the analysis with P 5 0.001 uncorrected with a cluster threshold of 80 contiguous voxels.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Semantic knowledge can be generalized to many different contexts, providing undifferentiated conceptual information that is likely to be drawn upon for the construction of future events.

    “In contrast, semantic knowledge can be generalized to many different contexts (Mion et al., 2010), providing undifferentiated conceptual information that is likely to be drawn upon for the construction of future events (Binder and Desai, 2011).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Mion et al., 2010 source

      Not checked in the free run.

    • cites Binder and Desai, 2011 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Midline brain structures may play a particularly crucial role in mediating self-referential thought.

    “Midline brain structures may play a particularly crucial role in mediating self-referential thought (Northoff et al., 2006).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Northoff et al., 2006 source

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    Taken together, these results highlight the importance of personal semantic information for imagining the future self, and converge with our present findings to show the importance of the semantic memory system for future-oriented thought.

    “Taken together, these results highlight the importance of personal semantic information for imagining the future self (Duval et al. 2012), and converge with our present findings to show the importance of the semantic memory system for future-oriented thought.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Duval et al. 2012 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Age was included as a covariate in all contrasts.

    “Age included as a covariate in all contrasts.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    Our findings point towards a critical role of the semantic memory system in supporting the simulation of future events, in concert with contributions from episodic memory.

    “Importantly, our findings point towards a critical role of the semantic memory system in supporting the simulation of future events, in concert with contributions from episodic memory.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductnone given

    All results were uncorrected at P < 0.001; only clusters with at least 80 contiguous voxels were included.

    “All results uncorrected at P 5 0.001; only clusters with at least 80 contiguous voxels were included.”
    Quote in the paperNot a substantial claim
73 of 73

  • The paper relies on this without support.

    The experimental tasks validly measure episodic and semantic future thinking.

    “This study investigated the capacity for future-oriented thought across episodic and semantic domains in patients with semantic dementia and Alzheimer's disease”

  • The paper relies on this without support.

    The control group is healthy and comparable to the patient groups on relevant variables.

    “Compared with controls, patients with semantic dementia showed significant atrophy in the anterior temporal lobes bilaterally”
2 of 2

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Episodic components encoded in memories for certain events are scaffolded onto a semantic structure representing general information.

    “the episodic components encoded in memories for certain events, say a trip to the shops, are scaffolded onto a semantic structure representing general information on how such events typically exist and transpire [43–45]”

    From Is episodic-like memory <i>like</i> episodic memory? (2024) · cites this paper as [43]

Statistics recomputed

Every reported test result, recomputed from its test statistic and degrees of freedom. A result shows as not adding up only once an independent check has confirmed it.

  • ConsistentF(2, 29) = 4.122reported p = .027 · recomputed p = .027

    “F(2, 29) = 4.122, p = .027”

  • ConsistentF(2, 28) = 9.847reported p = .001 · recomputed p < .001

    “F(2,28) = 9.847, p = .001”

2 of 2

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Naming correlation is marked significant despite P = 0.058

    Minor

    The semantic dementia naming correlation is marked with an asterisk, which the table defines as P < 0.05. Its footnote instead reports P = 0.058.

  • Temporal-pole correlation is claimed for both groups but reported for only one

    Minor

    The discussion claims a temporal-pole correlation with semantic future thinking in both patient groups. Table 4 lists a right temporal-pole cluster for semantic dementia and controls, but no temporal-pole cluster for Alzheimer's disease and controls.

2 of 2

Cites

Flagged first, then by citations

Research works printed but not linked: 5

  1. Andersson, 2007, Non-linear optimisation. FMRIB Technical Report TR07JA1
  2. Andersson, 2007, Non-linear registration, aka Spatial normalisation. FMRIB Technical Report TR07JA2
  3. Baddeley, 1994, The Doors and People Test: a test of visual and verbal recall and recognition
  4. Meyers, 1995, The Meyers Scoring System for the Rey complex figure and the recognition trial: professional manual
  5. Schmidt, 1996, Rey Auditory and Verbal Learning Test: A handbook

Cited by

Sorted by citations

Related

Authors
Irish, M., Addis, D. R., Hodges, J. R., & Piguet, O.
Affiliations
Australian Research Council (AU)
ORCID
Venue
Brain
Publisher
Oxford University Press (OUP)
Published
2012-05-22
Volume
135
Issue
7
Pages
2178-2191
ISSN
  • 0006-8950 (ISSN-L)
  • 1460-2156
DOI
10.1093/brain/aws119
OpenAlex
W2136646528
Semantic Scholar
4814162c78bf690d37022c1b51c915a75049d6d4
Cited by
405
References
98
Citations by year
2026: 16 · 2025: 11 · 2024: 23 · 2023: 14 · 2022: 29 · 2021: 28 · 2020: 58 · 2019: 45 · 2018: 32 · 2017: 30 · 2016: 39 · 2015: 28 · 2014: 29 · 2013: 16 · 2012: 6
FWCI
18.02
Type
journal article
Language
en
Open access
Locations
  • Brain (publishedVersion)
  • PubMed (publishedVersion)
  • UNSWorks (UNSW Sydney) (submittedVersion, cc-by-nc-nd)
  • UNSWorks (University of New South Wales, Sydney, Australia) (submittedVersion, cc-by-nc-nd)
Funders
  • Royal Society Te Apārangi (UOA0810, RDF-10-UOA-024)
  • Centre of Excellence in Cognition and its Disorders, Australian Research Council (CE110001021)
  • Medical Research Council
  • National Health and Medical Research Council (1022684, FF0776229)
Topics
  • Health Sciences › Medicine › Psychiatry and Mental health › Dementia and Cognitive Impairment Research
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Memory Processes and Influences
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Neurobiology of Language and Bilingualism
Keywords
semantic memory, episodic future thinking, semantic dementia, Alzheimer's disease, episodic memory, dementia subtypes, neurodegeneration, inferior temporal gyrus, temporal pole, posterior cingulate cortex, parahippocampal gyrus, frontal pole, brain atrophy, self-projection
MeSH terms
Aged, Alzheimer Disease, Atrophy, Brain, Brain Mapping, Female, Humans, Magnetic Resonance Imaging, Male, Memory, Middle Aged, Neuropsychological Tests, Mental Recall, Thinking, Case-Control Studies, Frontotemporal Lobar Degeneration, Memory, Episodic

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-09.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-09.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

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