Cited by 605Schizophrenia research and treatmentMental Health and PsychiatryDementia and Cognitive Impairment Research

The global cognitive impairment in schizophrenia: consistent over decades and around the world

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Schaefer, Jonathan, Giangrande, Evan, Weinberger, Daniel R., Dickinson, Dwight·2013·Schizophrenia Research

Abstract

Objective Schizophrenia results in cognitive impairments as well as positive, negative, and disorganized symptomatology. The present study examines the extent to which these cognitive deficits are generalized across domains, potential moderator variables, and whether the pattern of cognitive findings reported in schizophrenia has remained consistent over time and across cultural and geographic variation.Method Relevant publications from 2006 to 2011 were identified through keyword searches in PubMed and an examination of reference lists. Studies were included if they (1) compared the cognitive performance of adult schizophrenia patients and healthy controls, (2) based schizophrenia diagnoses on contemporary diagnostic criteria, (3) reported information sufficient to permit effect size calculation, (4) were reported in English, and (5) reported data for neuropsychological tests falling into at least 3 distinct cognitive domains. A set of 100 non-overlapping studies was identified, and effect sizes (Hedge's g) were calculated for each cognitive variable.Results Consistent with earlier analyses, patients with schizophrenia scored significantly lower than controls across all cognitive tests and domains (grand mean effect size, g=-1.03). Patients showed somewhat larger impairments in the domains of processing speed (g=-1.25) and episodic memory (g=-1.23). Our results also showed few inconsistencies when grouped by geographic region.Conclusions The present study extends findings from 1980 to 2006 of a substantial, generalized cognitive impairment in schizophrenia, demonstrating that this finding has remained robust over time despite changes in assessment instruments and alterations in diagnostic criteria, and that it manifests similarly in different regions of the world despite linguistic and cultural differences.

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Crossref · 10.1016/j.schres.2013.07.009

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  • Earlier studies failed to account for general cognitive, motor, or emotional impairments linked to schizophrenia.

    “However, previous studies assessed either voluntary imitation [7][8][9][10][25][26][27][28][29][30][31] or automatic imitation of emotional stimuli 12,13,32,33 while not controlling for the cognitive, motoric, and/or emotional deficits associated with the disorder.”

    From Enhanced Automatic Action Imitation and Intact Imitation-Inhibition in Schizophrenia (2019) · cites this paper as [32]

    The Introduction and Discussion report generalized cognitive impairment in schizophrenia, supporting the cognitive-deficit premise. They do not assess whether earlier imitation studies controlled for cognitive, motoric, or emotional deficits; searches for imitation and those potential confounds did not establish that methodological claim. No page numbers were supplied for the indexed passages. (LLM, conf=0.82)

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  • Tasks requiring deliberate imitation place demands on general cognitive functions that are impaired in schizophrenia and are not unique to imitation.

    “voluntary tasks are (to varying degrees) taxing on a range of cognitive processes that are known to be impaired in schizophrenia, 32 but which are not specifically tied to imitation.”
  • Earlier work on imitation in schizophrenia used either voluntary imitation tasks or automatic imitation of emotional stimuli.

    “However, previous studies assessed either voluntary imitation [7][8][9][10][25][26][27][28][29][30][31] or automatic imitation of emotional stimuli 12,13,32,33 while not controlling for the cognitive, motoric, and/or emotional deficits associated with the disorder.”

    From Enhanced Automatic Action Imitation and Intact Imitation-Inhibition in Schizophrenia (2019) · cites this paper as [32]

    The Methods section describes a review of cognition and neuropsychology in schizophrenia, not imitation studies. Searches for voluntary imitation, automatic imitation, emotional stimuli, and controls for motoric or emotional deficits found no passage addressing the attributed claim. (LLM, conf=0.75)

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  • Schizophrenia sometimes involves overimitation, manifesting as echolalia or echopraxia.

    “Indeed, overimitation is sometimes seen in schizophrenia in the form of symptoms like echolalia or echopraxia.31,32”

    From Enhanced Automatic Action Imitation and Intact Imitation-Inhibition in Schizophrenia (2019) · cites this paper as [32]

    The Introduction describes broad cognitive impairment and a variety of symptoms in schizophrenia, but does not address overimitation, echolalia, or echopraxia. Searches for those terms and for imitation or repetitive speech and actions found no passage supporting the specific claim. (LLM, conf=0.76)

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Authors
Schaefer, J., Giangrande, E., Weinberger, D. R., & Dickinson, D.
Affiliations
National Institutes of Health (US)
Venue
Schizophrenia Research
Publisher
Elsevier BV
Published
2013-10
Volume
150
Issue
1
Pages
42-50
ISSN
0920-9964 (ISSN-L)
OpenAlex
W2104347649
Cited by
605
References
138
Citations by year
2026: 33 · 2025: 44 · 2024: 40 · 2023: 46 · 2022: 46 · 2021: 53 · 2020: 53 · 2019: 61 · 2018: 52 · 2017: 60 · 2016: 41 · 2015: 50 · 2014: 21 · 2013: 4
FWCI
5.15
Type
journal article
Language
en
Open access
Locations
  • Schizophrenia Research (publishedVersion)
  • PubMed (publishedVersion)
  • PubMed Central (acceptedVersion)
Funders
  • National Institutes of Health (Z99 MH999999)
  • National Institute of Mental Health (ZIAMH002712)
Topics
  • Health Sciences › Medicine › Psychiatry and Mental health › Schizophrenia research and treatment
  • Social Sciences › Arts and Humanities › Philosophy › Mental Health and Psychiatry
  • Health Sciences › Medicine › Psychiatry and Mental health › Dementia and Cognitive Impairment Research
Keywords
schizophrenia, cognitive impairment
MeSH terms
Cognition Disorders, Humans, Neuropsychological Tests, Schizophrenia, Schizophrenic Psychology, Meta-Analysis as Topic, Databases, Bibliographic

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