The high prevalence of psychiatric comorbidity in drug dependent individuals is well known. However, there is limited literature available regarding the comorbidity of psychiatric disorders in drug addicts on methadone maintenance treatment (MMT).

To determine the comorbidity of mental disorders in patients on MMT.

The Symptom Checklist 90-Revised (SCL-90R) [1] was completed by 85 drug addicts (65 male and 20 female) on MMT. We recorded demographic data, duration of addiction, and duration of MMT.

The mean age of the sample was 42.0 ± 8.8 years old, the mean duration of substance use was 24.3 ± 8.2 years and the mean duration of MMT was 6.8 ± 4.1. The majority of participants (78.8%) were unemployed and 58.3% of them had no children. Participants scored higher on the depression, paranoid ideation, anxiety, hostility, somatization, interpersonal sensitivity and psychoticism SCL-90R sub-scales, with average scores >1 [2]. On the contrary, lower scores were recorded in the obsessive-compulsive and phobic anxiety sub-scales. The percentage of participants that reported abnormal scores for each sub-scale was as follows: 89.3% for depression, 83.3% for paranoid ideation, 74.7% for anxiety, 66.7% for hostility, 64.7% for somatization, 51.2% for psychoticism and 35.7% for phobic anxiety. No abnormal scores were recorded regarding obsessive-compulsive symptoms. Only 8.4% of participants did not score abnormally on any sub-scale.

Drug-addicted patients on MMT show a high comorbidity of psychiatric disorders. In particular, the likely presence of depressive and paranoid symptoms should be taken into serious account when deciding on a therapeutic strategy.