Scientists have for the first time 'isolated' the genetics of mania in bipolar disorder

Researchers from King's College London and the University of Florence said they have for the first time been able to isolate the "genetic architecture" of mania, a key symptom of bipolar disorder that distinguishes it from other mental illnesses. The work is published in Biological Psychiatry.

The main difficulty in studying the biology of mania is that people with bipolar disorder often also have depressive episodes (and sometimes psychotic symptoms). Because of this, genetic signals get "mixed up," and it becomes difficult to know which relates specifically to mania. In the new study, the team used large international genetic arrays - including data from more than 27,000 people with severe bipolar disorder and more than 576,000 participants studied in the context of depression.

The scientists used a statistical approach that can be simplistically described as "subtracting" the genetic effects associated with depression from the signals observed in bipolar disorder. This allowed mania to be viewed as a separate biological process - not as a "mixture" of mania and depression, but as an independent component.

Following the analysis, the researchers concluded that mania explained more than 80 per cent of the genetic variation associated with bipolar disorder and identified 71 genetic variants associated specifically with mania, including 18 genetic regions not previously associated with bipolar disorder. Among the biological pathways affected, the authors highlight genes associated with potential-dependent calcium channels important for signalling between neurons and mood regulation.

The authors emphasise the practical significance of the results: many people first seek help during depressive episodes, which can make bipolar disorder appear for a long time as "just depression" or be confused with other diagnoses. A clearer understanding of the biology of mania, they argue, brings the search for early biomarkers closer and may shorten the path to proper diagnosis and treatment.