A comparative study on dual patients with affective disorder.

Background: The main purpose of the study was to investigate whether there are differences between dual patients with affective disorders regarding the different kinds of substances abused - a topic which has hardly been dealt with in the literature.

Methods: Clinical charts of 94 dual and 94 non-dual patients, matched for sex, age, and diagnosis, were scrutinized and the data of both groups compared with each other, with regard to the substance of abuse.

Results: A total of 17.4% of all patients with affective disorders were found to be dual patients and the proportion of dual patients was equal among patients with unipolar disorder, bipolar disorder, and dysthymia. Only a few significant differences were found between dual and non-dual patients; more differences were identified when the dual group was divided into patients abusing alcohol (59%), opioids/cocaine (22%), and sedatives/hypnotics (19%). In particular, the group of patients abusing illegal drugs was found to be younger and to show more behavioral pathology. All three groups of dual patients differed regarding the onset of their affective illness.

Limitations: Retrospective study of clinical records.

Conclusions: There are differences between dual patients with affective disorders abusing different substances. The choice of a particular substance of abuse appears to be the function of the age of onset of the disorder.