Individual differences in mood reactions to d-amphetamine: a test of threepersonality factors

Individual differences in self-reported mood following either 5 mg or 10 mg d-amphetamine challenge were examined in order to test the modifying role of three factors of personality, viz., the Eysencks' psychoticism, Cloninge r's novelty seeking, and Depue and Collins' extraversion. In a double-blind study, mood measures (energetic arousal, tense arousal, and hedonic tone) were taken immediately following a single-dose of d-amphetamine and then ag ain after 90 min. The results showed significant psychoticism x d-amphetami ne interactions for both drug doses: d-amphetamine increased energetic arou sal and hedonic tone, and reduced tense arousal, only in low psychoticism i ndividuals; in high psychoticism individuals, it led to lowered energetic a rousal and hedonic tone, and increased tense arousal. Neither novelty seeki ng nor extraversion modified the effects of d-amphetamine. These data sugge st a link between psychoticism and dopaminergic functioning, although they do not rule out the involvement of other transmitter systems (e.g. noradren ergic), In common with other studies, such findings point to the important role that well-established factors of personality play in accounting for in dividual differences in reactions to psychoactive drugs. It is concluded th at the routine inclusion of personality measures in future psychopharmacolo gical studies may help to refine the characterization of drug effects.