Persuasive evidence of the same genetic cause for bipolar and schizophrenia was published this month in Lancet (January 16, 2009). The study, conducted by medical scientists in the Department of Medical Epidemiology and Biostatistics Karolinska Institutet, a Swedish university medical center, included two million families. There is a growing body of evidence that suggests a link between the issues, but the researchers claim this study shows positive proof, according to a press release from Karolinska Institutet.
Karolinska’s researchers looked at records of 35,985 people with schizophrenia, 40,487 people with bipolar, and their relatives. Both genetic and environmental factors were considered, and they found that genes played a remarkably larger part in determining incidence of both issues than did environmental factors. They concluded that 1) people with a relative who has schizophrenia or bipolar are at greater risk of developing one of the issues; 2) people with a relative who has one of the issues are likely to have another relative with either one of the issues, and 3) people with schizophrenia are more likely to develop bipolar than others. The study found that sisters and brothers of people with either issue were nine times more likely to develop bipolar or schizophrenia.
This news is important to researchers who, for decades, have studied the issues independent of each other. Bipolar is classified as a mood disorder and schizophrenia as a psychotic disorder in the Diagnostic and Statistical Manual of Mental Disorders, the most commonly used diagnostic manual in North America. This information is also likely to be of interest to genetics counselors and families in which one or more members have or had either or both of issues.
© Copyright 2009 by Jolyn Wells-Moran, PhD, MSW. All Rights Reserved. Permission to publish granted to GoodTherapy.org.
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