Are the rates of schizophrenia unusually high in Canada?
A comparison of Canadian and international data
Marie-José Dealberto dealbert at queensu.ca
Department of Community Health and Epidemiology, Carruthers Hall, Queen's University, Kingston, Ontario, Canada K7L 3N6
Psychiatry Research Received 3 March 2012; received in revised form 26 September 2012; accepted 9 January 2013. published online 25 February 2013.
Two major risk factors for schizophrenia are present in Canada, high latitude and a large and growing immigrant population. Consequently, one would expect unusually high rates of schizophrenia and an increase in these rates over time. This systematic review tests these two hypotheses. Searches of electronic databases were performed through 2011. Out of 45 studies 12 fulfilled all the inclusion criteria. The means of Canadian and international rates were compared by one-tailed unequal variance t-test. Trends with time in Canadian rates were tested by the Spearman rank correlation coefficient.
Prevalence and incidence rates in Canada were significantly higher than those in international studies. Rates increased over time, with a significant increase for prevalence and a trend for incidence. This rise was supported by historical data, recent hospital admission data, and the only Canadian cohort study. The findings of elevated rates in Canada and their increase over time give concern due to the serious personal, social, and financial burden of schizophrenia. These results, based on a small number of studies, warrant confirmation by specially designed studies. They could explain the discrepant results of the risk associated with immigration in Canadian studies.
Preliminary results were presented in an oral presentation: ‘Are rates for schizophrenia unusually high in Canada?’ at the Psychotic Disorders Section, 60th Canadian Psychiatric Association Conference, Toronto, September 23–26, 2010.
References are at the bottom of this page
See also VitaminDWiki
- Overview Schizophrenia and Vitamin D which has the following summary Feb 2013:
- (Vitually) all patients with schizophrenia are vitamin D deficient
- Schizophrenia varies with latitude (UVB) by 10X (controversy)
- Schizophrenia is more common in those with dark skin (when away from the equator)
- Schizophrenia has been increasing around the world when vitamin D has been decreasing (controversy)
- Schizophrenia is associated with low natal vitamin D
- Schizophrenia is associated with low birth rate, which is associated with low vitamin D
- Schizophrenia is associated with Autism which is associated with low vitamin D
- Vitamin D, light and mental health file
- Psychosis in dark skinned people 3.5 X higher if low level of vitamin D – May 2012
- Overview Pregnancy and vitamin D
400 IU of vitamin D for mother-to-be ==> 3X less adolescent Schizophrenia
- All items in Winter Blues and Vitamin D _
- SAD rate 10X higher in cloudy Seattle than sunny Florida - April 2011
Anticipate higher rate of Schizophrenia in Seattle as well - but have not found the data so far
- Infants 2X more likely to get schizophrenia if had very low vitamin D – Sept 2010
- Schizophrenia and vitamin D have latitude-related genes – Nov 2010 which has the following graphic
Schizophrenia high and increasing in Canada – lower vitamin D and more dark skin – Feb 2013
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- SAD rate 10X higher in cloudy Seattle than sunny Florida - April 2011