According to a recent literature analysis by Dr. Ranga Krishnan of Duke University Medical Center, more than half of people with bipolar disorder also have a substance use disorder. New findings suggest than genes contribute to this comorbidity. One-third of the genes that have been linked with bipolar disorder in four recent studies have also been associated with substance dependence, according to Dr. George R. Uhl and colleagues at the NIDA Intramural Research Program. The team analyzed data from comparisons of genetic profiles of European-Americans with and without bipolar disorder. Bipolar disorder was linked with 69 genes, and Dr. Uhl's team had previously tied 23 of those genes to risk for substance abuse (see "New Technique Links 89 Genes to Drug Dependence"). Variants of these genes may affect the two disorders directly and may also interact to increase vulnerability to one or both conditions.
American Journal of Medical Genetics: Part B Neuropsychiatric Genetics 150B(2):182-190, 2009. [Abstract]