Aggressive responding of male heroin addicts under methadone treatment: psychometric and neuroendocrine correlates

Objective measures of experimentally-induced aggressiveness were evaluated in 20 methadone-treated heroin addicts, in comparison to 20 normal healthy male subjects. All the subjects were submitted to preliminary DSM IV interv iews, Buss Durkee Hostility Inventory (BDHI) and Minnesota Multiphasic Pers onality Inventory (MMPI II). During a laboratory task, the point subtractio n aggression paradigm (PSAP), subjects earned monetary reinforcers with rep eated button presses, and were provoked by the subtraction of money, which was attributed to a fictitious other participants. Subjects could respond b y ostensibly subtracting money from the fictitious subject (the aggressive response), or protecting their counter (escape response). Money-earning res ponses were significantly lower (t=4.38, P<0.001) and aggressive responses significantly higher (t=5.45; P<0.001) in methadone patients in comparison to controls. During the experimentally-induced aggressiveness, plasma adren ocorticotropic hormone (ACTH), cortisol (CORT) and growth hormone (GH) conc entrations increased significantly less and norepinephrine (NE) and epineph rine (EPI) levels, together with heart rate (HR), significantly more in met hadone subjects than in healthy subjects. PSAP aggressive responses positiv ely correlated with catecholamines changes, BDHI 'direct' and 'irritability ' scores, MMPI 'psychopathic deviate' scores both in methadone subjects and controls, and with CORT responses only in healthy subjects. No correlation was found between methadone doses, or exposure extent, and aggressiveness levels. Our findings suggest that heroin dependent patients have higher out ward-directed aggressiveness than healthy subjects, in relationship with mo noamines hyper-reactivity, also under methadone medication. Aggressiveness in methadone patients seems to be related more to the personality traits th an to drug effects. Hypothalamus-pituitary-adrenal (HPA) axis responses, un expectedly dissociated from catecholamines rise among methadone patients, c ould be due to a long-lasting inhibitory action exerted by opiates on pro-o pio-melanocortin (POMC), or to a premorbid psychobiological condition that exhausted hormonal reactivity. (C) 2001 Elsevier Science Ireland Ltd. All r ights reserved.