What Is Bipolar Disorder?
While “unipolar” depression is associated only with low mood, bipolar disorder is illustrated by extreme changes in mood. There are different categories of bipolar disorder, but they all feature periods of debilitating depression that can rapidly swing to periods of euphoric highs and intense levels of energy.
In most cases, the age of onset for bipolar disorder is in the mid-20s. Evidence suggests that the earlier bipolar disorder sets in, the more severe the associated signs and symptoms will be.
What Causes Bipolar Disorder?
The precise cause of bipolar disorder is not yet clear. However, evidence suggests that genetic inheritance as well as brain structure and function influence whether someone will develop bipolar disorder. Unlike many other depressive disorders, environmental factors are not believed to play a significant role in the development of bipolar disorder.
However, some evidence suggests that childhood trauma may be associated with increased rates of bipolar disorder in adults who are already predisposed to its development. Trauma later in life can also unmask and exacerbate the signs and symptoms of bipolar disorder. Similarly, so-called “drug-induced” bipolar disorder is unlikely to actually be caused by drug use — instead, drug use unmasks a disorder that was already present.
A recent study found that a gene called “suppressor of cytokine signaling” (SOCS) is present in higher levels in people with bipolar disorder, especially men. These preliminary findings suggest that the development of bipolar disorder may be related to immune system dysfunction. It also indicates that there are some differences in how bipolar disorder develops in men versus women.