A personality trait associated with amphetamine-induced euphoria is not automatically a predictor of better memory or attention. Kassim’s 2023 review makes that distinction especially useful: the literature connecting personality to subjective drug effects was more developed than the evidence connecting personality to objective cognitive changes.
Two kinds of review within one paper
The paper systematically reviewed double-blind, placebo-controlled amphetamine experiments in healthy, non-sleep-deprived adults, searching PubMed and Scopus through March 2022. Its discussion of personality, however, was a narrative review. The two components did not have identical search and selection methods.
The working-memory account included 18 full-text studies plus one abstract. The broader cognition component included 37 independent studies and used abstract findings for two reports whose full texts were unavailable. These are study counts, not a single cohort receiving a common dose. Patients, children, older populations, sleep-deprived participants and coadministration experiments were outside the specified systematic-review scope.
Subjective and objective endpoints ask different questions
Subjective endpoints included arousal, euphoria, drug wanting and related experiences. Objective endpoints included performance on working-memory and other cognitive tasks. A questionnaire about how a participant feels cannot replace a count of correct responses, response times or errors.
The narrative discussion described associations involving sensation seeking, impulsivity, reward sensitivity and other traits. Its central limitation was that few studies directly tested whether personality modified amphetamine’s objective cognitive effects. Associations between personality and drug liking, between personality and baseline memory, and between drug exposure and dopamine are not a completed demonstration of personality-dependent cognitive benefit.
The working-memory findings discourage a single prediction rule
Seven studies reported main or time-dependent effects on spatial working memory, while five reported no effect in that part of the review. Only one study reported an effect on verbal working memory; eight did not. The paper’s table and narrative coverage should be retained rather than converting the entire literature into a percentage of people who improve.
These were heterogeneous tasks and dose schedules. The review discussed low, moderate and higher doses, including experiments with approximately 5–40 mg dexamphetamine. Such a range is not an individualized dose recommendation or proof of a common dose–response curve. Faster responding in one task also need not mean greater memory capacity.
Does an inverted-U explanation resolve the uncertainty?
The review considered the hypothesis that different baseline dopamine function or working-memory ability could produce opposite drug responses. This is a plausible organizing account, not a validated personality-based treatment algorithm. Some cited genotype and baseline-performance findings supported moderation; others did not find the proposed differences.
Crucially, a personality questionnaire is not a direct measurement of a person’s brain dopamine concentration. The paper itself noted the lack of an exact match between a single personality trait and dopamine. Combining several correlational observations cannot identify an individual’s optimal pharmacological state.
What would support an individual prediction?
A useful predictive study would specify the trait and cognitive endpoint in advance, compare drug with placebo, test the trait-by-treatment interaction and validate the prediction in additional participants. Merely finding significance in one personality subgroup and nonsignificance in another would not establish that their responses differ.
The historical review supports investigating individual variation while preserving the unresolved link. It does not establish that sensation seeking, impulsivity or any other trait can determine whether a particular person will perform better after amphetamine. It likewise supplies no personality-based rule for interpreting impairment at a specific event.
Source
Kassim FM. 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. Human Psychopharmacology: Clinical and Experimental. 2023;38(1):e2856; published online in 2022. doi:10.1002/hup.2856. Systematic cognitive reviews with a narrative personality component.
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