Depression is widely prevalent among former heroin addicts in methadone maintenance treatment (MMT). The risk factors for depression among MMT patients that have not been well characterized, was studied.

In a cross-sectional study (January, 2004–August, 2005), 90 MMT patients were evaluated for depression by the 21-item Hamilton Rating Scale for Depression (21-HAM-D) and the Brief Psychiatric Rating scale (BPRS). To study possible induction of depression by drug abuse, urine samples tested for opiates, cocaine metabolite (benzoylecgonine), benzodiazepines (BDZ), cannabis (THC), amphetamines and methadone metabolite during 1 month preceding study entry: a drug was defined as being positive if at least one sample was positive.

The 21-HAM-D and BPRS scores were significantly correlated (Pearson R=0.76, p<0.0005). Fifty percent were found to be suffering from depression (21-HAM-D, scored ≥18). Fifteen new patients in MMT had better scores (5.1±5.7) than continuous patients (17.7±6.2, p<0.0005), independent of treatment duration. Higher scores were in 51 patients with any Axis I psychiatric diagnosis (18.9±5.7 vs. 11.4±7.9, p<0.0005), 74 abusing and or using prescribed BDZ (16.3±7.4 vs. 11.7±8, p=0.03), and 36 prescribed more than one type of medication (17.5±7.3 vs. 14.2±7.7, p=0.05). Females (N=40) had poorer scores than males (17.6±7 vs. 14.1±7.9, p=0.03), especially 12 admitted into treatment while pregnant (20.2±4.1).

Patient drug abuse and withdrawal could distort evaluation and lead to misclassification of depression.

The major risk factors for depression were already being in MMT, female gender, any DSM-IV Axis I psychiatric diagnosis, taking any psychotropic medication, abuse or using prescribed BDZ, and methadone dose >120 mg/day.