PLASMA-CORTISOL CORRELATES OF IMPULSIVITY AND SUBSTANCE ABUSE

Biological models of impulsivity frequently propose the concept of 'trait low arousal' as an explanation for the sensation-seeking and rule-breaking behavior observed in such individuals. In this work, baseline activity of the hypothalamic-pituitary-adrenal (HPA) axis, as measured by plasma cortisol, was selected to test for the relationship between impulsivity and HPA-axis arousal. In addition, differences in plasma cortisol between patients with a current diagnosis of substance abuse and normal controls were sought. Fifty-three subjects (medication free averaging 10 weeks) and 20 normal controls comprised the sample assessed. Impulsivity was measured by a subscale of the Eysenck Personality Inventory. Plasma cortisol was drawn at 8:00 a.m. after an overnight fast. Results showed that the substance abusers had a significantly lower level of plasma cortisol than the controls. Moreover, within the control group cortisol was negatively correlated with impulsivity. The findings suggest that the HPA-axis may furnish a useful signal to test arousal models of personality and behavior. © 1990.