Cortisol effects of D-amphetamine relate to traits of fearlessness and aggression but not anxiety in healthy humans

The current study utilized personality measures thought to relate to noradrenergic and catecholamine function (i.e., sensation seeking, anxiety and aggression) to investigate individual differences in amphetamine-induced increases in cortisol. The goal of the study was to better understand variations in responses to psychostimulants in healthy volunteers. Method: A placebo-controlled within-subjects investigation of salivary cortisol responses to oral D-amphetamine (20 mg) was conducted in seventy (N=70) young adults. Personality traits were assessed using the Eysenck Personality Inventory (EPI), Sensation Seeking Scale Form V (SSS-V) and the Multidimensional Personality Questionnaire-Brief Form (MPQ-BF). Results: A more rapid rise in salivary cortisol after D-amphetamine was associated with SSS-V Thrill Seeking (r=-0.32 with time to peak, p < 0.05). A greater peak increase in cortisol and a greater recovery after amphetamine was positively associated with MPQ-BF Aggression (r=+0.35, p < 0.05; r=+0.38, p < 0.05). In contrast, cortisol responses were unrelated to a composite measure of trait anxiety (EPI/MPQ-BF Anxiety Index). Conclusions: The findings suggest that the personality traits of aggression and thrill seeking are related to cortisol responses to D-amphetamine, raising the possibility that personality may predispose certain individuals to use drugs through a glucocorticoid pathway. The data also suggest a distinction between fear and anxiety, as amphetamine-induced cortisol responses were associated with measures of trait fear but not measures of trait anxiety in the current sample. (c) 2006 Elsevier Inc. All rights reserved.