Systematic reviews of the acute effects of amphetamine on working memory and other cognitive performances in healthy individuals, with a focus on the potential influence of personality traits

Wardle et al. (2013) reported that amphetamine (5, 10 and 20 mg) enhances executive function in a dose-dependent manner in 177 participants.

“Wardle et al. (2013) reported that AMP (5, 10 and 20 mg) enhances executive function in dose‐dependent manner in 177 participants.”

• cites Wardle et al., 2013 sourceDisputed

  The study used 5, 10 and 20 mg doses, and the Methods (Measures; page unavailable) give n = 177 for the b-WCST analysis. But the Results (Typical amphetamine effects; page unavailable) report dose-dependent improvement in processing speed, not executive functioning; the Abstract explicitly says amphetamine did not affect executive functioning. (LLM, conf=0.93)

  Checked by a reasoning model — may be wrong.

  Experimental — accuracy not yet measured

AMP does not have consistent effects on subjective measures.

“AMP does not have consistent effects on subjective measures”

• cites Allen & Gabbay, 2013 sourceSupported
• cites Harvanko et al., 2016 sourceDisputed

  The Discussion states that 8 or 16 mg d-amphetamine produced consistent increases in subjective effects. The Results (“d-Amphetamine Effects”) also report dose-related increases across several self-report ratings. Our copy provides section labels but no page numbers. (LLM, conf=0.90)

  Checked by a reasoning model — may be wrong.

  Experimental — accuracy not yet measured
• cites Hutchison et al., 1999 sourceNot checked — no full text of the source

Amphetamine has limited cognitive effects in healthy subjects.

“Although AMP and its derivatives have modest cognitive benefits as prescription stimulants and enhance motivation and energy in heathy subjects, studies have shown that they have limited cognitive effects in heathy subjects (see Ilieva & Farah, 2013; Simons et al., 2012).”

• cites Ilieva & Farah, 2013 sourceSupported
• cites Simons et al., 2012 sourcePartly supported

  The Results (Cognitive tasks; page unavailable) report no significant differences on several tasks and a nonsignificant advantage for dexamphetamine on vigilance, supporting limited effects on the measures tested. But the Discussion reports better divided-attention performance, and the study tested one 10 mg dose of dexamphetamine in a small group of volunteers; it does not establish a general claim about amphetamine’s cognitive effects in healthy subjects. (LLM, conf=0.82)

  Experimental — accuracy not yet measured

Working memory performance in psychotic and healthy subjects relies on dopamine levels within the prefrontal cortex.

“Studies have shown that WM performance in psychotic and healthy subjects rely on dopamine levels within the PFC (Dumontheil et al., 2011; Mattay et al., 2003; Okubo et al., 1997).”

• cites Dumontheil et al., 2011 sourcePartly supported

  The Discussion (p. 14) says PFC functioning and working-memory performance have been suggested to vary with dopamine levels, supporting the general relationship. The paper examines developmental effects of COMT genotype, however, and does not establish this relationship in psychotic subjects; its Discussion (p. 15) mentions psychiatric populations only as a context for interpreting developmental findings. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites Mattay et al., 2003 sourcePartly supported

  The Abstract states that prefrontal dopamine signaling is critical for working memory, and the paper reports dopamine-related differences in prefrontal function during a working-memory task in healthy volunteers. It does not establish the same relationship in psychotic subjects; the Discussion mentions schizophrenia only as a condition for which the findings may be relevant. (LLM, conf=0.87)

  Experimental — accuracy not yet measured
• cites Okubo et al., 1997 sourceNot checked — no full text of the source

Increased dopamine release can impair working memory.

“indicating that increased dopamine release can impair WM, as is seen in people with schizophrenia with a similar test of WM (Abi‐Dargham et al., 2002; Van Snellenberg et al., 2016).”

• cites Abi‐Dargham et al., 2002 sourcePartly supported

  The Discussion says excessive dopamine release can overstimulate D1 receptors and is associated with worse working memory in primates. But this study measured D1 receptor availability, not dopamine release, in people with schizophrenia; its Conclusions favor a chronic deficit in presynaptic dopamine function as an explanation for their poor n-back performance. It therefore does not establish that increased release is what was seen in those patients. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites Van Snellenberg et al., 2016 sourcePartly supported

  The Introduction links dopamine function in the dorsolateral prefrontal cortex to working-memory performance and notes dopaminergic abnormalities in schizophrenia. It does not say that increased dopamine release impairs working memory; the cited paper's reference list instead includes a study titled 'Deficits in prefrontal cortical and extra-striatal dopamine release in schizophrenia.' (LLM, conf=0.84)

  Experimental — accuracy not yet measured

Dopamine is associated with personality traits.

“In addition to WM, studies further indicate the association of dopamine with personality traits (Derringer et al., 2010; DeYoung, 2013; Kaasinen et al., 2001; Kim et al., 2013).”

• cites Derringer et al., 2010 sourceSupported
• cites DeYoung, 2013 sourceSupported
• cites Kaasinen et al., 2001 sourceSupported

The prefrontal cortex plays a key role in working memory in both healthy subjects and people with psychiatric disorders such as schizophrenia.

“The prefrontal cortex (PFC) plays a key role in WM in both healthy subjects and people with psychiatric disorders, such as schizophrenia (see Kane & Engle, 2002 for review; Lett et al., 2014; Slifstein et al., 2015).”

• cites Kane & Engle, 2002 sourcePartly supported

  The Human Research section says that studies with healthy subjects and brain-injured patients show significant dorsolateral PFC involvement in working-memory tasks, particularly when information must be maintained despite interference. The copy does not establish the same working-memory role in people with schizophrenia; its mention of schizophrenia in the Conclusions concerns healthy adults matched to schizophrenia patients, not the patients’ working memory. (LLM, conf=0.85)

  Experimental — accuracy not yet measured
• cites Lett et al., 2014 sourceNot checked — no full text of the source
• cites Slifstein et al., 2015 sourceSupported

Mattay et al. (1996) reported that amphetamine enhances general intelligence on Ravens Progressive Matrices in the same participants.

“However, Mattay et al. (1996) reported that AMP enhances general intelligence on Ravens Progressive Matrices (RPM) in the same participants.”

• cites Mattay et al., 1996 sourceSupported

Five studies did not find an effect of amphetamine on learning or memory.

“The remaining five studies did not find an effect of AMP on learning or memory (Cavanagh et al., 2022; Comer et al., 1996; Makris et al., 2007; Mintzer & Griffiths, 2003; Patat et al., 1996).”

• cites Cavanagh et al., 2022 sourcePartly supported

  The Results > Performance section (page unavailable) reports no drug effect on mice’s task performance, and the small-scale mouse replication found no accuracy difference between drug conditions. But human performance showed a drug-by-sex interaction, with females tending to perform slightly worse at higher doses. The paper therefore does not support an unqualified claim of no effect on learning or memory; it does not report a memory outcome. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites Comer et al., 1996 sourceNot checked — no full text of the source
• cites Makris et al., 2007 sourceNot checked — no full text of the source

Mattay et al. (1996) reported that amphetamine (0.25 mg/kg or approximately 18 mg) did not affect performance on the Wisconsin Card-Sorting Task in eight participants.

“Mattay et al. (1996) reported that AMP (0.25 mg/kg or ∼18 mg) did not affect performance on WCST in eight participants”

• cites Mattay et al., 1996 sourceSupported

Personality traits influence the subjective effects of amphetamine.

“several studies also reported that personality trait influence the subjective effects of AMP (Allen & Gabbay, 2013; Harvanko et al., 2016; Kirkpatrick et al., 2013; see White, 2017 for review).”

• cites Allen & Gabbay, 2013 sourcePartly supported

  The Discussion section (“Amphetamine Challenge as a Measure of the Stimulant Response”; page unavailable) says personality traits have been empirically associated with the amphetamine response. But it says the present analyses did not evaluate those traits, so this paper does not itself show that they influence amphetamine’s subjective effects. (LLM, conf=0.84)

  Experimental — accuracy not yet measured
• cites Harvanko et al., 2016 sourceSupported
• cites Kirkpatrick et al., 2013 sourceSupported

Some studies reported a lack of AMP effects on inhibitory control, verbal memory, learning, or intelligence.

“However, other studies reported a lack of AMP effects on inhibitory control, as well as verbal memory, learning, inhibitory control or intelligence (Cavanagh et al., 2022; Comer et al., 1996; Fillmore et al., 2005; Ilieva et al., 2013; Makris et al., 2007; Mintzer & Griffiths, 2003; Patat et al., 1996)”

• cites Cavanagh et al., 2022 sourcePartly supported

  The Results > Performance section (page not provided) reports no drug effect on performance in mice during a probabilistic learning task, offering limited support for the learning portion. It does not report a lack of amphetamine effects on inhibitory control, verbal memory, or intelligence; in humans, it reports a drug-by-sex interaction rather than a general absence of effect. (LLM, conf=0.82)

  Experimental — accuracy not yet measured
• cites Comer et al., 1996 sourceNot checked — no full text of the source
• cites Fillmore et al., 2005 sourcePartly supported

  The Abstract and Discussion (section 4) report no improvement in inhibitory control after d-amphetamine in the healthy adults studied. This paper does not report a lack of effects on verbal memory, learning, or intelligence, which are also included in the citing sentence. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

Four of eight studies using CPT, RIP, or RVIP reported that amphetamine improves performance accuracy or reaction time.

“Four of the eight studies reported that AMP improves performance accuracy or reaction time (RT): four measured performance using CPT (Bhakta et al., 2022; Fleming et al., 1995; Krystal et al., 2005; Patat et al., 1996) but only two of them found main effects of AMP.”

• cites Bhakta et al., 2022 sourceSupported
• cites Fleming et al., 1995Not checked — no full text of the source
• cites Krystal et al., 2005 sourceNot checked — no full text of the source

Dopamine release or elevation in the striatum positively correlates with scores on schizotypy measures in non-clinical subjects.

“Studies showed that dopamine release or elevation in the striatum positively correlates with scores on schizotypy measures in non‐clinical subjects (see Mohr & Ettinger, 2014 for review; Woodward et al., 2011).”

• cites Mohr & Ettinger, 2014 sourcePartly supported

  The molecular-imaging section reports significant correlations between amphetamine-induced striatal dopamine release and schizotypy scores in healthy volunteers. It does not specify that those correlations were positive, so that direction of the claim is not established by our copy. (LLM, conf=0.83)

  Experimental — accuracy not yet measured
• cites Woodward et al., 2011 sourceSupported

Differences in personality traits such as sensation-seeking and impulsivity are modulated by striatal dopaminergic transmission.

“Previously studies suggested that differences in personality traits such as sensation‐seeking and impulsivity are modulated by striatal dopaminergic transmission (Derringer et al., 2010; Gjedde et al., 2010; see Munafò et al., 2008; Norbury & Husain, 2015 for review).”

• Also stated in: § Future perspectives: Is dopamine a linking neural substrate of both personality traits and working memory performance? · boosted

  “supporting the evidence that differences in personality traits are modulated by striatal dopaminergic transmission.”

• cites Derringer et al., 2010 sourcePartly supported

  The Abstract (page unavailable) links dopamine to individual differences in sensation seeking and reports an association between nucleus accumbens dopamine receptor availability and impulsivity in rodents. The Discussion (page unavailable) reports that dopamine-gene variants explain variation in sensation seeking. The paper does not establish that striatal dopaminergic transmission modulates both traits in humans; its own analysis concerns genes and sensation seeking, not striatal transmission or impulsivity. (LLM, conf=0.85)

  Experimental — accuracy not yet measured
• cites Gjedde et al., 2010 sourceNot checked — no full text of the source
• cites Norbury & Husain, 2015 sourceNot checked — no full text of the source

Dexamphetamine increases schizotypy scores in healthy subjects.

“and increases schizotypy scores in healthy subjects (Abi‐Dargham et al., 2004; Woodward et al., 2011)”

• cites Abi‐Dargham et al., 2004 sourceNot checked — no full text of the source
• cites Woodward et al., 2011 sourceCould not verify

  The Methods (Assessments and Study Procedures; page unavailable) say participants completed the Schizotypal Personality Questionnaire before scanning. The Results (Correlation between overall schizotypal traits and dopamine release; page unavailable) report a correlation between questionnaire scores and amphetamine-induced dopamine release, not a change in schizotypy scores. A post-amphetamine increase in those scores cannot be verified from this copy. (LLM, conf=0.76)

  Experimental — accuracy not yet measured

Dexamphetamine elevates the synaptic concentration of dopamine in the striatum and extra-striatum.

“It has been well established that dexamphetamine elevates the synaptic concentration of dopamine in the striatum and extra‐striatum (Martinez et al., 2003; Woodward et al., 2011)”

• cites Martinez et al., 2003 sourceNot checked — no full text of the source
• cites Woodward et al., 2011 sourceSupported

Dependence to AMP or cocaine is influenced by anxious-impulsive personality traits.

“dependence to AMP or cocaine is influenced by anxious‐impulsive personality traits (Ersche et al., 2012).”

• cites Ersche et al., 2012 sourcePartly supported

  The Abstract Conclusions say anxious-impulsive traits may be endophenotypes associated with the risk of cocaine or amphetamine dependence. This supports a possible risk relationship, but the claim’s unqualified “is influenced by” states it more definitively than the paper does. (LLM, conf=0.85)

  Experimental — accuracy not yet measured

Schizotypy trait has been linked to alterations in the dopaminergic system.

“Importantly, schizotypy trait have been linked to alterations in the dopaminergic system.”

• cites Mohr & Ettinger, 2014 sourceSupported
• cites Woodward et al., 2011 sourceSupported

Schizotypy traits are influenced by the baseline level of dopamine release.

“supporting the suggestion that schizotypy traits are influenced by the baseline level of dopamine release (Rössler et al., 2019).”

• cites Rössler et al., 2019 sourcePartly supported

  The Discussion (page unavailable) suggests that dopamine availability may have been enhanced in placebo recipients with positive schizotypal traits, and the paper links those traits to dopamine-related connectivity. It does not measure baseline dopamine release or establish that baseline release levels influence schizotypy traits; the claim is more specific than the paper’s inference. (LLM, conf=0.84)

  Experimental — accuracy not yet measured

Schizotypy is generally associated with impairments in WM.

“studies reported that schizotypy is generally associated with impairments in WM”

• cites Giakoumaki, 2012 sourceNot checked — no full text of the source
• cites Rossi et al., 2016 sourcePartly supported

  The Introduction (Background) says a large body of work reports an association between working-memory deficits and schizotypy. It also says the results are mixed, so the claim’s unqualified suggestion of a general pattern overstates the source. (LLM, conf=0.85)

  Experimental — accuracy not yet measured
• cites Schmidt‐Hansen & Honey, 2009 sourceNot checked — no full text of the source

Personality trait modulates or is linked to objective measures, particularly WM.

“studies showed that personality trait modulates or is linked to objective measures (i.e., cognitive ability), particularly to WM”

• cites Dima et al., 2015 sourceSupported
• cites Gray & Braver, 2002 sourceSupported
• cites Li et al., 2021Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Some studies did not find COMT-dependent differences in executive or WM function after dexamphetamine administration.

“some studies did not find COMT‐dependent differences in executive or WM function after dexamphetamine (e.g., 5, 10 or 20 mg) administration”

• cites Ilieva et al., 2013 sourceCould not verify

  The Introduction reports no detectable Adderall effect on executive-function and memory measures, but does not discuss whether effects differed by COMT genotype. Searches for COMT-dependent responses and dexamphetamine doses found no passage addressing the claim; the paper's general finding about cognition cannot establish the claimed absence of COMT-dependent differences. (LLM, conf=0.76)

  Experimental — accuracy not yet measured
• cites Wardle et al., 2013 sourceSupported

AMP (10 and 20 mg) influences willingness to exert effort based on baseline WM, improving willingness in individuals with lower WM.

“a recent study reported that AMP (10 and 20 mg) influences willingness to exert effort based on baseline WM, improving willingness in individuals with lower WM”

• cites Soder et al., 2021 sourcePartly supported

  The Moderators section reports that both 10 mg and 20 mg d-amphetamine increased hard-task choices in participants with lower baseline working memory, but chiefly at low to intermediate expected reward values. It also states that working memory did not moderate the drug’s overall effect on willingness to exert effort. The claim omits that condition and could imply an overall effect. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

The association of traits in the Big Five model and WM showed mixed results.

“although the association of traits in the ‘Big Five’ model and WM showed mixed results (Dima et al., 2015; Waris et al., 2018).”

• cites Dima et al., 2015 sourceSupported
• cites Waris et al., 2018 sourceNot checked — no full text of the source

Optimal levels of dopamine in PFC are essential for WM performance.

“In general, optimal levels of dopamine in PFC are essential for WM performance”

• cites Brozoski et al., 1979 sourceNot checked — no full text of the source
• cites Kane & Engle, 2002 sourcePartly supported

  The section “Converging Models of PFC Involvement in Working-Memory Capacity” (page unavailable) describes dopamine circuits as potentially helping the PFC maintain and update working-memory representations, but calls the proposal speculative. It does not establish that optimal dopamine levels in the PFC are essential for working-memory performance. (LLM, conf=0.83)

  Experimental — accuracy not yet measured
• cites Robbins & Arnsten, 2009 sourceSupported

The inconsistency in AMP's subjective effects may be linked to between-person variations in personality traits such as sensation seeking.

“several studies suggested that this inconsistency may be linked to between‐person variations in personality traits such as sensation seeking”

• cites Allen & Gabbay, 2013 sourceSupported
• cites Harvanko et al., 2016 sourceSupported
• cites Hutchison et al., 1999 sourceNot checked — no full text of the source

Failing to include between-person variation in personality may result in a non-causal association.

“A study on the association between cognitive impairments and cannabis use suggested that failing to include between‐person variation in personality may result in a non‐causal association (Daly, 2013).”

• cites Daly, 2013 sourceSupported

The review included 19 working memory studies (18 full-text studies plus one abstract).

“Nineteen WM studies were included in the current review.”

• Also stated in: § Working memory · plain

  “A total of 18 WM (SWM and VWM) studies were included (Figure 1). An additional single abstract (Fleming et al., 1995) was included.”

Five studies reported no effect of amphetamine on spatial working memory.

“while five studies reported no effect of AMP on SWM.”

Few studies reported the impacts of personality traits on the objective (such as working memory) effects of amphetamine.

“However, few studies reported the impacts of personality traits on the objective (such as WM) effects of AMP.”

Eight studies found no effect of amphetamine on verbal working memory.

“and eight studies that used Digit Span, Digit Recall Task or Operation Span Task (OST) found no effect of AMP on VWM.”

Only one study found an effect of amphetamine on verbal working memory.

“Only one study that used Digit Span found an effect of AMP on VWM (de Wit et al., 2002)”

• cites de Wit et al., 2002Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Seven studies found either main effects or time-dependent effects of amphetamine on spatial working memory.

“Seven studies found either main effects or time‐dependent effects of AMP on SWM (Barch & Carter, 2005; Fleming et al., 1995; Makris et al., 2007; Mintzer & Griffiths, 2003; Ward et al., 1997b; Wardle et al., 2012; Willson et al., 2004)”

• cites Barch & Carter, 2005 sourceNot checked — no full text of the source
• cites Fleming et al., 1995Not checked — no full text of the source
• cites Makris et al., 2007 sourceNot checked — no full text of the source

Studies showed that personality traits are associated with the subjective effects of amphetamine.

“Studies also showed that personality traits are associated with the subjective effects of AMP.”

Twenty-two of the 37 cognitive studies reported effects of amphetamine on one or more cognitive tasks: attention, information processing speed, executive function, executive function component of working memory, inhibitory control, or learning and memory.

“Twenty two of them reported effects of AMP on one or more of the cognitive tasks: attention, information processing speed, executive function, executive function component of WM, inhibitory control or learning and memory.”

Thirty-seven independent studies on other aspects of cognitive performance were identified.

“Overall, 37 independent studies that used heterogeneous methodologies were included in the current review (Figure 1).”

There are insufficient studies on objective measures of personality traits' influence on amphetamine effects.

“Although there are insufficient studies on objective measures, studies also indicated that the subjective effects of AMP administration are linked to between‐person variations in personality traits.”

All studies except one showed that amphetamine does not enhance verbal working memory.

“In contrast, all studies except one showed that AMP does not enhance VWM.”

Few studies investigated the impacts of personality traits or baseline working memory capacity on the objective effects of amphetamine.

“Fourth, few studies investigated the impacts of personality traits or baseline WM capacity on the objective effects of AMP.”

Personality traits are associated with the dopaminergic system.

“First, studies have shown that personality trait is associated with the dopaminergic system.”

Seven studies reported that amphetamine improves verbal learning and memory, reward learning, and language production.

“Seven reported that AMP improves verbal learning and memory (Breitenstein et al., 2006; Whiting et al., 2007; Zeeuws et al., 2010a, 2010b; Zeeuws & Soetens, 2007), reward learning (Soder et al., 2021) and language production (Barch & Carter, 2005)”

• cites Breitenstein et al., 2006 sourceNot checked — no full text of the source
• cites Whiting et al., 2007Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Zeeuws et al., 2010aNot matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Personality traits such as novelty seeking, impulsivity, reward sensitivity, physical fearlessness or schizotypy are correlated with the subjective effects of amphetamine.

“Second, personality traits such as novelty seeking, impulsivity, reward sensitivity, physical fearlessness or schizotypy are correlated with the subjective effects of AMP.”

Eight of 14 studies using other attention tasks reported that amphetamine improves attention.

“Eight of the 14 studies reported that AMP improves attention (Asghar et al., 2003; Barch & Carter, 2005; Comer et al., 1996; Dolder et al., 2018; Servan‐Schreiber et al., 1998; Silber et al., 2006; Sofuoglu et al., 2008; Willson et al., 2004).”

• cites Asghar et al., 2003 sourceNot checked — no full text of the source
• cites Barch & Carter, 2005 sourceNot checked — no full text of the source
• cites Comer et al., 1996 sourceNot checked — no full text of the source

Thirteen of the 37 cognitive studies assessed the effect of amphetamine on learning and memory.

“out of the 37 cognitive studies, 13 studies assessed the effect of AMP on learning and memory.”

One study found that amphetamine impairs verbal learning and memory.

“while one study found that AMP impairs verbal learning and memory (Krystal et al., 2005).”

• cites Krystal et al., 2005 sourceNot checked — no full text of the source

Personality traits are linked to objective measures such as working memory.

“Third, studies have also shown that personality traits are linked to objective measures such as WM.”

Eight of the 14 studies that assessed attention reported that AMP improves selective attention.

“Importantly, although AMP has limited cognitive effects on most of the tasks, eight of the 14 studies that assessed attention reported that AMP improves selective attention.”

The current review shows that the effects of AMP are greater on DSST, selective attention, and reaction time than accuracy on various SWM tasks.

“The current review also shows that the effects of AMP are greater on DSST, selective attention, and reaction time than accuracy on various SWM tasks”

• cites Barch & Carter, 2005 sourceNot checked — no full text of the source
• cites Mintzer & Griffiths, 2003 sourceNot checked — no full text of the source
• cites Ward et al., 1997bNot matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Three of the four studies that reported AMP improves the response rate component of SWM used the SIRP task.

“Three (Makris et al., 2007; Ward et al., 1997a, 1997b; Willson et al., 2004) of the four studies that reported AMP improves the response rate component of SWM used SIRP task”

• cites Makris et al., 2007 sourceNot checked — no full text of the source
• cites Ward et al., 1997a, 1997bNot matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Willson et al., 2004 sourceNot checked — no full text of the source

Ten of the 20 studies that used the DSST, CPT or other WM tasks reported that AMP enhances performance.

“In addition, 10 of the 20 studies used that DSST, CPT or other WM tasks reported that AMP enhances performance.”

The current review is less conclusive about the influence of personality traits on the WM effects of AMP.

“making the current review less conclusive about the influence of personality traits on the WM effects of AMP.”

Only few studies investigated the impacts of personality traits on the objective effects of AMP.

“Only few studies investigated the impacts of personality traits on the objective effects of AMP”

This review shows that AMP studies found mixed effects on SWM and other aspects of cognitive function.

“To summarise, this review shows that AMP studies found mixed effects on SWM and other aspects of cognitive function.”

Pharmacological or environmental stress that increases dopamine activity in the prefrontal cortex of Rhesus monkeys impairs visuospatial working memory performance.

“pharmacological or environmental stress that increases dopamine activity in the PFC of Rhesus monkeys impairs visuospatial WM performance (Arnsten et al., 1994; Arnsten & Goldman‐Rakic, 1998)”

• cites Arnsten et al., 1994Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Arnsten & Goldman‐Rakic, 1998 sourceNot checked — no full text of the source

Amphetamine has mixed effects on other cognitive functions.

“Overall, findings indicate that AMP has mixed‐effects on spatial WM and other cognitive functions, but it lacks effects on verbal WM.”

The subjective effects of amphetamine administration are linked to between-person variations in personality traits.

“Although there are insufficient studies on objective measures, studies also indicated that the subjective effects of AMP administration are linked to between‐person variations in personality traits.”

Amphetamine has mixed effects on spatial working memory.

“Overall, findings indicate that AMP has mixed‐effects on spatial WM and other cognitive functions, but it lacks effects on verbal WM.”

Dopamine depletion or antagonism impairs visuospatial working memory.

“evidence from non‐human primates (Sawaguchi & Goldman‐Rakic, 1991, 1994; Williams & Goldmanrakic, 1995) and in healthy humans (Fischer et al., 2010) showed that dopamine depletion or antagonism impairs visuospatial WM.”

• cites Sawaguchi & Goldman‐Rakic, 1991 sourceNot checked — no full text of the source
• cites Williams & Goldmanrakic, 1995 sourceNot checked — no full text of the source
• cites Fischer et al., 2010 sourceNot checked — no full text of the source

Dopamine in the prefrontal cortex has an inverse-U-shaped association with working memory performance.

“have demonstrated that dopamine in the PFC possesses an inverse‐U‐shaped association with WM performance (Baldi & Bucherelli, 2005; Cools & D'Esposito, 2011).”

• cites Baldi & Bucherelli, 2005 sourceNot checked — no full text of the source
• cites Cools & D'Esposito, 2011 sourceNot checked — no full text of the source

Amphetamine lacks effects on verbal working memory.

“Overall, findings indicate that AMP has mixed‐effects on spatial WM and other cognitive functions, but it lacks effects on verbal WM.”

The effects of amphetamine on other cognitive functions are inconsistent.

“The effects of AMP on other cognitive functions are inconsistent (Listed in Tables 2 and 3).”

Various doses of dexamphetamine do not have consistent effects on working memory tasks.

“Overall, the studies indicate that various doses of dexamphetamine do not have consistent effects on WM tasks despite it was generally thought that AMP or its derivatives improve cognitive performances.”

Amphetamine reversed deficits in various cognitive and motor performances and complex expression identification following continuous sleep deprivation.

“AMP also reversed deficits in various cognitive and motor performances (Magill et al., 2003) and complex expression identification (Huck et al., 2008) following continuous sleep deprivation.”

• cites Magill et al., 2003 sourceNot checked — no full text of the source
• cites Huck et al., 2008 sourceNot checked — no full text of the source

Dose variation is not a reason for the lack of effects of dexamphetamine on working memory.

“Those studies that failed to find main or interactional effects of dexamphetamine on VWM (Dolder et al., 2018; Graham‐Schmidt et al., 2019; Ilieva et al., 2013; Mintzer & Griffiths, 2003; Patat et al., 1996; Schmedtje et al., 1988; Silber et al., 2006; Tselha et al., 2019) and SWM (Ilieva et al., 2013; Mattay et al., 1996, 2000; Pickworth et al., 1997; Wardle et al., 2012, 2013), used low (5 mg),”

The cognitive enhancing effects of amphetamine might be under suboptimal performance conditions such as sleep deprivation or after sedative medication.

“The cognitive enhancing effects of AMP might be under suboptimal performance conditions such as sleep deprivation or after sedative medication.”

Amphetamine reversed psychomotor and working memory impairments on selective tasks (n-back) after triazolam administration in healthy subjects.

“a study showed that AMP reversed psychomotor and WM impairments on selective tasks (n‐back) after triazolam administration in healthy subjects (Mintzer & Griffiths, 2003).”

• cites Mintzer & Griffiths, 2003 sourceNot checked — no full text of the source

Amphetamine might facilitate working memory function through its direct effects on other cognitive functions such as attention and information-processing speed.

“AMP might facilitate WM memory function through its direct effects on other cognitive functions such as attention and information‐processing speed.”

Schizotypy scores in healthy subjects vary based on differences in dopamine metabolising (COMT) enzymes.

“studies showed that schizotypy scores in healthy subjects vary based on the difference in dopamine metabolising (COMT) enzymes (Smyrnis et al., 2007; Stefanis et al., 2004)”

• cites Smyrnis et al., 2007 sourceNot checked — no full text of the source
• cites Stefanis et al., 2004 sourceNot checked — no full text of the source

The WM effect of AMP might depend on the task type.

“which might indicate that the WM effect of AMP depends on the task type.”

One study reported impairments of immediate and delayed recalls after AMP administration.

“while one study reported impairments of immediate and delayed recalls after AMP administration (Krystal et al., 2005).”

• cites Krystal et al., 2005 sourceNot checked — no full text of the source

Some findings indicate that AMP might facilitate WM rather than directly influencing WM capacity.

“Importantly, some findings indicate that AMP might facilitate WM rather than directly influencing WM capacity.”

The baseline level of dopamine or the personality trait score to begin with influences the biochemical and psychological effects of dexamphetamine.

“indicating the baseline level of dopamine or the personality trait score to begin with influences the biochemical and psychological effects of dexamphetamine.”

• cites Abi‐Dargham et al., 2004 sourceNot checked — no full text of the source

The effect of dexamphetamine on schizotypy scores is reversed by dopamine antagonist (e.g., haloperidol).

“and the effect is reversed by dopamine antagonist (e.g., haloperidol) (Angrist et al., 1974).”

• cites Angrist et al., 1974 sourceNot checked — no full text of the source

HVLT mainly measures verbal learning and memory capacity instead of WM.

“it has to be noted that HVLT mainly measures verbal learning and memory capacity instead of WM (Savla et al., 2007).”

• cites Savla et al., 2007 sourceNot checked — no full text of the source

Dopaminergic neuromodulation might influence WM based on the specific task type and load.

“suggesting that dopaminergic neuromodulation might influence WM based on the specific task type and load.”

• cites Eckart et al., 2014 sourceNot checked — no full text of the source

Evidence showed no well-defined association between cognitive effects and plasma concentration of dexamphetamine.

“Furthermore, evidence showed no well‐defined association between cognitive effects and plasma concentration of dexamphetamine (e.g., Asghar et al., 2003).”

• cites Asghar et al., 2003 sourceNot checked — no full text of the source

The cognitive effects of AMP are inconsistent.

“indicating that the cognitive effects of AMP are inconsistent.”

An important reason for the null-results of AMP on WM and other cognitive performances might be differences in baseline WM capacity.

“These results indicate that an important reason for the null‐results of AMP on WM and other cognitive performances might be because of differences in baseline WM capacity.”

Subjects who begin with higher dopaminergic activity would have impaired performance after dexamphetamine.

“indicating that subjects who begin with higher dopaminergic activity would have impaired performance after dexamphetamine.”

Including participants with opposite baseline WM capacity may result in lack of AMP effects.

“Including participants with opposite baseline WM capacity may result in lack of AMP effects.”

Baseline WM impacts a wide range of effects.

“which indicate that baseline WM impacts a wide range of effects.”

Individual differences in personality trait influence the subjective effects of AMP.

“Taken as a whole, the results indicate that individual differences in personality trait influence the subjective effects of AMP”

• Also stated in: § Future perspectives: Is dopamine a linking neural substrate of both personality traits and working memory performance? · hedged

  “Studies also showed that the subjective effects of AMP administration are likely linked to between‐person variations in personality traits such as sensation seeking”

• cites Norbury & Husain, 2015 sourceNot checked — no full text of the source

The WM effect of dopaminergic agents depends on the baseline dopamine level.

“Animal studies reported that the WM effect of dopaminergic agents (e.g., dihydrexidine or other D1 agonists) depends on the baseline dopamine level”

• cites Arnsten et al., 1994Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Cai & Arnsten, 1997 sourceNot checked — no full text of the source

Excluding personality trait factors may result in lack of AMP effects as the mean scores from opposite personality-trait individuals may mask possible associations.

“Furthermore, excluding personality trait factors may result in lack of AMP effects as the mean scores from opposite personality‐trait individuals may mask the possible associations.”