Researchers in Germany may have come closer to confirming one of the possible genetic components that contribute to a vulnerability to bipolar disorder. For some time, we have known two things about bipolar disorder:

• It’s a brain illness, a neurological disorder.
• It has a strong genetic component.

The unknown, until now, was the link between the genetic component and the actual neural abnormalities. Relatively recently, several studies have implicated a variant on chromosome 12, the CACNA1C gene, as increasing the risk for bipolar disorder. So researchers wanted to find out whether this gene variant could be traced to a particular region of the brain.

In a study published in the Archives of General Psychiatry, August 2010, entitled “Brain Function in Carriers of Genome-wide Supported Bipolar Disorder Variant,” researchers report to have identified a connection between the CACNA1C gene and the hippocampus – the brain’s memory center.

Participants in the study included 110 healthy volunteers of both genders. 50 of them carried copies of the CACNA1C risk variant for bipolar disorder, and 60 carried none. While performing a memory task, participants’ brains were scanned via fMRI imaging. fMRI images showed the following:

• Subjects with copies of the CACNA1C gene variant had significantly lower activation of the hippocampus during recall compared to those who carried no copies of the variant.
• Subjects with copies of the CACNA1C gene variant scored significantly higher on psychopathology scores for anxiety, depression, interpersonal sensitivity, obsessive-compulsive thoughts, and neuroticism than did subjects with no copies of the risk variant.

This study highlights the goldmine of information that is being uncovered through the fuller understanding of the human genome. The genes are the starting point. The next step, as demonstrated in this study, is to try to understand what parts of the brain the genes regulate. Then we can begin to look at how those brain centers are related to illness.

These findings don’t provide anything clinically meaningful in terms of diagnosis and treatment of bipolar disorder, but they do contribute to the rapidly expanding body of knowledge that will eventually put some of the pieces together – not just for diagnosis and treatment, but also for risk factors and prevention.

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A Step Closer to Confirming Genetic Link to Bipolar Disorder | Health News (October 7, 2010)

    Last reviewed: 5 Oct 2010