A new study finds that manic symptoms account for about 81.5% of the genetic variation that causes bipolar disorder.
For the first time, researchers isolated genetic factors specifically responsible for mania in bipolar disordera discovery that could lead to more accurate diagnoses and improved treatments for this serious mental health condition.
Bipolar disorder affects approximately 2% of the world population and is defined by extreme fluctuations in mood, with manic episodes marked by high energy and impulsivity, alternating with periods of deep depression. Despite its prevalence, the disorder remains difficult to diagnose and treat, in part because its symptoms overlap with those of other psychiatric conditions, such as major depressive disorder (MDD) and schizophrenia, says .
To unravel this complexity, researchers behind a new large-scale genetic study analyzed genomic data from more than 600,000 people, including 576,327 individuals with MDD and 27,196 diagnosed with bipolar disorder. By comparing the two groups, the team was able to subtract genetic signals linked to depression, leaving only those specifically associated with mania.
The results suggest that mania plays a much larger role in the genetic makeup of bipolar disorder than previously realized. According to what was published in Biological Psychiatry, manic symptoms represent about 81.5% of the variation genetics of the disorder, while depression contributes the remaining 18.5%.
The researchers also identified 71 genetic variants associated with mania, including 18 that had not previously been linked to bipolar disorder. Many of these genes are linked to characteristics often seen during manic episodes, such as reduced need for sleep, increased physical activity, elevated mood, risky behaviors and the tendency to stay up late. These associations help explain the bursts of energy and impulsivity that define mania.
Interestingly, genetic markers linked to mania showed weaker links to substance dependence than those associated with the depressive component of bipolar disorder. They also showed a lower correlation with risky sexual behavior, suggesting that some behaviors often attributed to mania may have more complex biological origins or different.
“By isolating the genetic architecture of mania, we have taken a crucial step toward understanding the core biology of bipolar disorder,” said lead author, Giuseppe Pierpaolo Merola. Rather than viewing bipolar illness as a simple mix of mania and depression, the findings help clarify what makes mania biologically distinct.
Several of the newly identified genes influence voltage-gated calcium channels, which play a key role in neuronal communication. This pathway may represent a promising target for future specific treatments for bipolar disorder.
