Depression and the severity of substance abuse

Psychosocial factors have been considered important in the initiation of drug abuse and seem to affect its clinical course and outcome. Several studies have reported psychopathology, namely depression, to be consistently high in addiction. The aim of this investigation was to evaluate the prevalence of depression and its relationship to the severity of drug abuse in a Portuguese sample of drug addicts.

Two hundred and eighty-five drug addicts (23 women and 262 men, aged between 16 and 41 years old), diagnosed according to the DSM-IV criteria, were contacted during their first visit for treatment at public health centres. Social, demographic and behavioural characteristics of the study sample were obtained by interview using a structured questionnaire. The severity of drug abuse was evaluated using a Portuguese version of the Drug Abuse Screening Test, and depression was assessed by the Zung self-rating depression scale.

The prevalence of depression was 51.2% and was higher in females than males (77.8 vs. 48.7%, p = 0.034). A significant correlation was also found between the severity of drug abuse and depression scores, which was also stronger in females (r = 0.53 vs. r = 0.24).

This study showed a high prevalence of depression in drug addicts, regardless of the type and duration of drug abuse, and a significant association between depression and severity of drug addiction.