Former heroin addicts with or without a history of cocaine dependence are more impulsive than controls

Abstract

Background: Personality traits such as impulsivity and sensation seeking may contribute to the initiation and maintenance of illicit drug use. Since studies have reported higher impulsivity and sensation seeking traits in cocaine dependent subjects, we were interested in determining whether former heroin addicts in methadone pharmacotherapy with comorbid cocaine addiction have greater impulsivity than those without.

Methods: Instruments to assess impulsivity (Barratt Impulsiveness Scale version 11) and sensation seeking (Sensation Seeking Scale version V) were administered to former severe heroin addicts meeting Federal criteria for methadone maintenance pharmacotherapy with (n = 71) or without cocaine dependence (n = 31) and to 145 normal healthy (non-methadone-maintained) volunteers.

Results: The methadone-maintained without cocaine dependence and the methadone-maintained with cocaine dependence groups, both scored higher than did the normal volunteer group on the Barratt Impulsiveness Scale total score (p<0.001). On the Barratt Impulsiveness Scale Attentional, Nonplanning, and Motor subscales, the methadone-maintained and methadone-maintained with cocaine dependence groups scored higher than did normal volunteers with no history of drug abuse or dependence (p<0.001). There was no difference among groups on total score or any subscale of the Sensation Seeking Scale. However, males in all groups overall scored higher than did females on Disinhibition and Thrill and Adventure seeking subscales of the Sensation Seeking Scale version V (p<0.001).

Conclusions: This study demonstrates higher impulsivity in former severe heroin addicts meeting criteria for or currently in stable methadone maintenance pharmacotherapy, irrespective of a positive or negative history of cocaine dependence.

Figure. 1

Barratt Impulsiveness scores (mean + s.e.m.) are shown in A: Total score, B: Attentional subscale, C: Nonplanning subscale, and D: Motor subscale for the normal healthy (non-methadone-maintained) volunteers (NV), methadone-maintained without cocaine dependence (former severe heroin addicts meeting eligibility requirements for methadone maintenance, MM), and methadone-maintained with cocaine dependence (former severe heroin addicts in methadone maintenance with comorbid cocaine dependence, MMCD) groups stratified by gender. Letter a indicates MM females greater than MM males for Total score (p < 0.001), Attentional subscale (p < 0.01), and Motor subscale (p < 0.005). Letter b indicates MM females greater than female NV in Total score and Attentional and Motor subscale (p < 0.001).

Figure. 2

Disinhibition (A) and Thrill and Adventure Seeking (B) subscale scores of the Sensation Seeking Scale. Scores (mean + s.e.m.) are shown for the normal healthy (non-methadone-maintained) volunteers (NV), methadone-maintained without cocaine dependence (MM), and methadone-maintained with cocaine dependence (MMCD) stratified by gender.

Figure. 3

Correlation of Total Sensation Seeking scores and Disinhibition subscale scores with age in female normal healthy (non-methadone-maintained) volunteers.