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

Kassim, Faiz M.

doi:10.1002/hup.2856

Cited by 6 publications

(7 citation statements)

References 223 publications

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“…Studies have shown that the objective or subjective effects amphetamine would be linked to between‐person variations in personality measures (Corr & Kumari, 2000; for review, see Kassim, 2022; Kelly et al., 2006; Kirkpatrick et al., 2013; see also White, 2017). For example, a study showed that subjective effects of three different doses of dexamphetamine (5, 10 and 20 mg) in healthy individuals were associated with individual differences in personality trait (Kirkpatrick et al., 2013).…”

Section: Discussionmentioning

confidence: 99%

Dexamphetamine influences funneling illusion based on psychometric score

Kassim

Lim

Albrecht

et al. 2023

Human Psychopharmacology

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Objectives Our team previously showed that like the experience of the rubber hand illusion (RHI) in people with schizophrenia and their offspring¸ dexamphetamine administration to healthy volunteers increases the stimulus binding windows (BWs) in RHI. It is not clear if similar expansions of BWs are present for unimodal illusions. Studies have also shown that subjective or objective effects of amphetamine would be linked to between‐person variations in personality measures. Therefore, we aimed to examine the effect of dexamphetamine (DEX), a dopamine‐releasing stimulant, on illusory perception using unimodal sensory stimuli (Tactile Funneling Illusion [TFI]) across both temporal and spatial variables. We further examined the relationship between changes in psychometric scores and changes in illusion perception induced by dexamphetamine. Methods Healthy subjects (N = 20) participated in a randomized, double‐blind, counter‐balanced, placebo‐controlled, cross‐over study. The effects of dexamphetamine (0.45 mg/kg, PO, q.d.) on funneling and error of spatial localization (EL) were examined using TFI. Psychotomimetic effects were assessed using a battery of psychological measures. Results Dexamphetamine did not significantly increased the funneling illusion (p = 0.88) or EL (p = 0.5), relative to placebo. However, the degree of change in psychometric scores following dexamphetamine positively correlated with changes in funneling (ρ = 0.48, p = 0.03, n = 20), mainly at 0 ms delay condition (ρ = 0.6, p = 0.004, n = 20). Conclusion Unlike multimodal illusions, alteration of BWs does not occur for unimodal illusions after administration of a dopamine‐releasing agent. However, our findings indicate that moderate release of dopamine, through its psychotomimetic effect, indirectly influences unimodal illusion.

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Section: Discussionmentioning

confidence: 99%

Dexamphetamine influences funneling illusion based on psychometric score

Kassim

Lim

Albrecht

et al. 2023

Human Psychopharmacology

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“…Although there are some studies that did not find effects of amphetamine on SWM, other studies did detect effects of amphetamine SWM ([ 6 , See 12 for review, 16 , 17 , 19 , 22 , 107 , 108 ]). We show that d-amphetamine also indirectly influences SWM, based on PLE score.…”

Section: Discussionmentioning

confidence: 99%

“…All of the studies (except one [ 31 ]) that used digit span tasks (DST) to examine verbal WM (VWM) reported that d-amphetamine did not affect performances on DST. The findings indicate that DST is not a sensitive tool to detect the effects of d-AMP on WM, ([for review, see 12 ]). In addition, there were no differences in effects of d-amphetamine that used either forward, backward or both tasks of the DS, which again implies that the recall direction is not sensitive to detect the effects of d-amphetamine on WM [ 32 ].…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, different studies have used different tasks to measure SWM. Furthermore, individual differences in personality traits such as neuroticism and schizotypy are important factors that may also cause performance differences on WM tasks among individuals ([for detail, see 56 , 57 ]). It has been suggested that dopamine may play the linking role between schizotypy/PLE and WM performance [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

“…Several studies have shown that amphetamine improves subjective ratings of arousal and perceived enhancements [5], and objective measures of cognitive performance in sleep-deprived participants [6][7][8][9][10][11]. However, the cognitive enhancing effects of amphetamine healthy subjects are mixed and more inconclusive on the general domain cognition [12].…”

Section: Introductionmentioning

confidence: 99%

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The effects of caffeine and d-amphetamine on spatial span task in healthy participants

Kassim,

Lim,

Slawik

et al. 2023

PLoS ONE

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Studies that examined the effect of amphetamine or caffeine on spatial working memory (SWM) and verbal working memory (VWM) have used various tasks. However, there are no studies that have used spatial span tasks (SSTs) to assess the SWM effect of amphetamine and caffeine, although some studies have used digit span tasks (DST) to assess VWM. Previous reports also showed that increasing dopamine increases psychosis-like experiences (PLE, or schizotypy) scores which are in turn negatively associated with WM performance in people with high schizotypy and people with schizophrenia. Therefore, the present study aimed to examine the influence of d-amphetamine (0.45 mg/kg, PO), a dopamine releasing stimulant, on SST, DST, and on PLE in healthy volunteers. In a separate study, we examined the effect of caffeine, a nonspecific adenosine receptor antagonist with stimulant properties, on similar tasks. Methods: Healthy participants (N = 40) took part in two randomized, double-blind, counter-balanced placebo-controlled cross-over pilot studies: The first group (N = 20) with d-amphetamine (0.45 mg/kg, PO) and the second group (N = 20) with caffeine (200 mg, PO). Spatial span and digit span were examined under four delay conditions (0, 2, 4, 8 s). PLE were assessed using several scales measuring various aspects of psychosis and schizotypy. Results: We failed to find an effect of d-amphetamine or caffeine on SWM or VWM, relative to placebo. However, d-amphetamine increased a composite score of psychosis-like experiences (p = 0.0005), specifically: Scores on Brief Psychiatric Rating Scale, Perceptual Aberrations Scale, and Magical Ideation Scale were increased following d-amphetamine. The degree of change in PLE following d-amphetamine negatively and significantly correlated with changes in SWM, mainly at the longest delay condition of 8 s (r = -0.58, p = 0.006). Conclusion: The present results showed that moderate-high dose of d-amphetamine and moderate dose of caffeine do not directly affect performances on DST or SST. However, the results indicate that d-amphetamine indirectly influences SWM, through its effect on psychosis-like experiences. Trial registration. Clinical Trial Registration Number: CT-2018-CTN-02561 (Therapeutic Goods Administration Clinical Trial Registry) and ACTRN12618001292268 (The Australian New Zealand Clinical Trials Registry) for caffeine study, and ACTRN12608000610336 for d-amphetamine study.

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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

Kassim

2022

Human Psychopharmacology

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Objectives This research aimed to systematically review the acute effects of amphetamine (AMP), a dopamine‐releasing agent, on working memory (WM) and other cognitive performances. The investigation also aimed to review the impact of personality traits on the subjective and objective effects of AMP and possible links between personality traits and effects of AMP. Methods Previous double‐blind controlled studies assessing the main effects of AMP on WM and other cognitive performances in healthy volunteers were systematically reviewed. An electronic search was performed in the PUBMED and SCOPUS databases. Narrative reviews of the influence of personality traits on the subjective and objective effects of AMP were included. Results Nineteen WM studies were included in the current review. Seven studies found effects of AMP on spatial WM, but only one study found the effect of AMP on verbal WM. Thirty‐seven independent studies on other aspects of cognitive performance were identified. Twenty‐two reported effects of AMP on cognitive functions. Studies also showed that personality traits are associated with the subjective effects of AMP. However, few studies reported the impacts of personality traits on the objective (such as WM) effects of AMP. Conclusion Overall, findings indicate that AMP has mixed‐effects on spatial WM and other cognitive functions, but it lacks effects on verbal WM. 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.

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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

Cited by 6 publications

References 223 publications

Dexamphetamine influences funneling illusion based on psychometric score

Dexamphetamine influences funneling illusion based on psychometric score

The effects of caffeine and d-amphetamine on spatial span task in healthy participants

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

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