Addiction and bipolar disorder are commonly co-occurring disorders, with up to 60% of individuals with bipolar disorder experiencing some form of substance abuse in their lifetime. While it is known that genetic factors contribute substantially to the likelihood of developing either illness, new studies suggest shared genetic roots for both disorders.
Researchers, partly funded by NIDA, analyzed data from five different genome-wide association studies (GWAS), which compared DNA from individuals diagnosed with either bipolar disorder or substance abuse disorder. GWAS scan an individual’s entire genome to identify SNPs (i.e., single-nucleotide polymorphisms) or slight changes in a gene’s sequence that may be associated with a particular disease.
In this analysis, researchers found remarkable convergence in at least three of the studies, identifying 69 common “bipolar disorder vulnerability” genes, 23 of which also contained clustered SNPs associated with substance abuse vulnerability. These findings provide evidence of a common genetic architecture between substance abuse and bipolar disorder, suggesting that variants in “addiction/bipolar” genes can potentially influence the brain in ways that increase a person’s vulnerability to both conditions.
The results of this study “promise to enhance understanding of features that are common to human addictions and bipolar disorder in ways that could facilitate efforts to personalize prevention and treatment strategies for these debilitating diseases,” conclude the authors.
Johnson C, Drgon T, McMahon FJ, Uhl GR. Convergent genome wide association results for bipolar disorder and substance dependence. Am J Med Genet B Neuropsychiatr Genet. 2009 Mar 5;150B(2):182-90.