Courses of substance use and schizophrenia in the dual-diagnosis patients: is there a relationship?

ABSTRACT

BACKGROUND: Interrelationship of schizophrenia and substance use is complex and multifactorial. Examining the influence of various psychoactive substances on course of patients with pure dual-diagnosis schizophrenia may help to solve this riddle. AIM: To examine the relationship of the courses of substance use and schizophrenic symptomatology in substance abusing "dual-diagnosis" patients with schizophrenia. SETTINGS AND DESIGN: Outpatient Deaddiction and Treatment Center of a tertiary care hospital with a retrospective design. METHODS and MATERIAL: Twenty-two substance abusing dual-diagnosis patients with schizophrenia were investigated regarding the course of substance use (abuse/dependence, use, non-use) and that of schizophrenia (psychotic, non-psychotic, in remission). A graphical representation of course of schizophrenia and substance abuse was made and their relationship studied by superimposition of respective graphs. STATISTICS The Friedman two-way analysis of variance of ranks was applied to see the relationship between time spent by patients while on and off various substances. RESULTS: In five cases, the onset of schizophrenia preceded the onset of substance use. In seven out of 22 subjects, the schizophrenic exacerbation was clearly preceded by increase in substance abuse in the preceding two-twelve months. In none of the subjects decrease in substance use led to a decrease or increase in schizophrenic symptoms. CONCLUSIONS: Although substance use disorder preceded the onset of schizophrenic illness in the majority, and increase in substance abuse preceded schizophrenic exacerbation in one-third of dual-diagnosis patients, overall there was no evidence that the course of substance use was associated with that of schizophrenia after both disorders were diagnosed.