Examining the Onset of Bipolar Disorder from a Genetic Perspective

David Chen, MD, is a psychiatrist who maintains a Chevy Chase, Maryland, practice and has undertaken research in areas such as the diagnosis and treatment of co-morbid addictions and early-onset bipolar disorder. In a National Institutes of Health (NIH) presentation, David Chen, MD, addressed “When Does Bipolar Disorder (BD) Begin? Genetic Approaches to Age At Onset.”

As Dr. Chen describes it, mental health disease is often not defined from the outset, as a condition progressing over stages, but as an end stage. Hs aim is to improve genetic and biological understanding, such that the pathophysiology for conditions such as BD can be defined from the outset.

Like any physical condition, BD has a cumulative lifetime risk and past studies have involved interviews with people with bipolar disorder. These involve subjects recalling the earliest BD onset and how it came about. In categorizing people in earlier and later onset subgroups, common factors are assessed as well as gene identification of a disorder that is highly heritable.

For early onset cases, maternal and paternal age at time of birth appear to have a connection with advancing parental age predicting an earlier age for a person’s first BD treatment. Later onset disease appears to have different causes, such as silenced cerebral infarctions. At the genome level Dr. Chen and his colleagues identified three novel risk loci for bipolar disorder. They also identified a connection between copy number variants (CNV) and earlier BD onset. CNV occurs when the number of copies of a specific gene varies from between one generation and the next. These losses and gains of genetic material seem to add to risk of bipolar disorder developing at an earlier age.