Mania - Causality

Most researchers believe bipolar disorders have a biological basis. And this stance is supported by findings that close relatives of those with bipolar disorder are significantly more likely to develop affective disorders than are relatives of people with no history of psychiatric illness. Theories of the underlying biological mechanisms have centered on concentrations of various neurotransmitters in the nerve connections of the brain. Because neurotransmitter interactions are subtle, complex, and obviously hard to observe, the strongest supportive and discerning evidence for the roles of specific neurotransmitters comes from the differential efficacy of various drug treatments. The fact that patients diagnosed with bipolar disorder respond differently to various drugs indicates there may be more than one type of bipolar disorder with different biological bases.