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Biol Psychiatry. 2013 Aug 15;74(4):280-6. doi: 10.1016/j.biopsych.2013.01.027. Epub 2013 Feb 28.

Polygenic risk and white matter integrity in individuals at high risk of mood disorder.

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  • 1Division of Psychiatry, University of Edinburgh, Edinburgh, United Kingdom. heather.whalley@ed.ac.uk



Bipolar disorder (BD) and major depressive disorder (MDD) are highly heritable and genetically overlapping conditions characterized by episodic elevation and/or depression of mood. Both demonstrate abnormalities in white matter integrity, measured with diffusion tensor magnetic resonance imaging, that are also heritable. However, it is unclear how these abnormalities relate to the underlying genetic architecture of each disorder. Genome-wide association studies have demonstrated a significant polygenic contribution to BD and MDD, where risk is attributed to the summation of many alleles of small effect. Determining the effects of an overall polygenic risk profile score on neuroimaging abnormalities might help to identify proxy measures of genetic susceptibility and thereby inform models of risk prediction.


In the current study, we determined the extent to which common genetic variation underlying risk to mood disorders (BD and MDD) was related to fractional anisotropy, an index of white matter integrity. This was conducted in unaffected individuals at familial risk of mood disorder (n = 70) and comparison subjects (n = 62). Polygenic risk scores were calculated separately for BD and MDD on the basis of genome-wide association study data from the Psychiatric GWAS Consortia.


We report that a higher polygenic risk allele load for MDD was significantly associated with decreased white matter integrity across both groups in a large cluster, with a peak in the right-sided superior longitudinal fasciculus.


These findings suggest that the polygenic approach to examining brain imaging data might be a useful means of identifying traits linked to the genetic risk of mood disorders.

Copyright © 2013 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.


Bipolar disorder; diffusion tensor MRI; major depressive disorder; mood disorder; polygenic; white matter

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