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Experts believe bipolar disorder is partly caused by an underlying problem with specific brain circuits and the balance of brain chemicals called neurotransmitters. Three brain chemicals -- noradrenaline (norepinephrine), serotonin, and dopamine -- are involved in both brain and bodily functions.. A. Doctors don't completely understand the causes of bipolar disorder. But they've gained a greater understanding in recent years of the bipolar spectrum, which includes the elated highs of mania to the lows of major depression, along with various mood states between these two extremes.
The younger the age of onset of bipolar disorder, the more likely it is to find a significant family history of the condition. Early onset bipolar disorder most commonly begins with depression and there may be many episodes of depression before the first hypomania. Depression with psychotic features may be a predictor of future full-blown bipolar disorder in the early onset group. Akiskal (1995) has argued that syndromal dysthymia with its onset in childhood, particularly in the presence of a family history of bipolar disorder, may herald a bipolar disorder.