Dual diagnosis, the effects of substance abuse on patients with schizophrenia

Comorbidity between Axis I mental disorders and substance use disorders range from 5%--60% (Farrell, 1998; Fowler, 1998). It has been suggested that dually diagnosed patients are inadequately treated for both disorders and that they are problematic from a diagnostic, clinical management and economic perspective. Dual Diagnosis (DD) maybe associated with a number of issues including increased aggression, increased non-compliance with medication (Swartz, 1998), and exacerbated psychopathology (Tomasson, 1997). However, contradictory evidence has also been found (Leon, 1998), which suggests that patients with DD may be a higher functioning population of mentally ill patients. The objectives of the present study were to determine the prevalence and clinical characteristics of dual diagnosis patients in a chronic psychiatric population. A sample of 217 patients with schizophrenia spectrum disorders was randomly sampled from the psychiatric facilities of the Montreal General Hospital. Almost half of the sample presented with comorbid addictive disorders; the most common drugs abused were alcohol, cannabis and cocaine. Those patients who had a lifetime diagnosis of substance abuse or dependence were more likely to be male, had a more severe course of psychiatric illness, higher rates of psychiatric symptomology, were more likely to be tobacco smokers and had higher rates of non-compliance with psychiatric medications. Further analyses revealed lower levels of social support and more legal problems in patients with DD, all of which may negatively impact on the quality of care for dual diagnosis patients in the clinical setting