Is schizophrenia on the decline in Canada?

Objective: To examine changes in prevalence rates of treated schizophrenia over 10 years in a small urban teaching centre using data from the Kingston Psychiatric Record Linkage System (KPRLS). Method: The KPRLS, a psychiatric case register established in 1984, collect s and links demographic, diagnostic, and service use information for all ps ychiatric inpatients, outpatients and emergency contacts at the 3 hospitals in Kingston, Ontario. A preliminary comparison of first admissions for sch izophrenia used chart review (1976-1978) and KPRLS data (1996-1998). The KP RLS data were used to calculate population-based-prevalence rates of treate d schizophrenia in 3 census years (1986, 1991, 1996)for patients in the 2 c ounties closest to Kingston. Results: The preliminary comparison showed a 42% decrease in the number of first-admission schizophrenia cases over 20 years. In the main study, the a nnual inpatient prevalence rates decreased significantly (52%)from 1986 to 1996 with no corresponding change in outpatient rates, regardless of sex. A lthough total major affective disorders increased, this was due to an incre ase in major depression, not bipolar disorder. Conclusions: This is the first Canadian case-register study to support the widely reported falling rates of schizophrenia in other parts of the world over the last 40 years. Since this is a geographically limited prevalence s tudy based on only 10 years of data, further research over longer periods o f time in other regions of the country, is required to support or refute th ese findings.