What causes bipolar disorder?
There is no single, proven cause of bipolar disorder, but it is often an inherited problem related to a lack of stability in the transmission of nerve impulses in the brain. This biochemical problem makes people with bipolar disorder more vulnerable to emotional and physical stresses. An upsetting life experience, substance use, lack of sleep, or other excessive stimulation might cause normal brain mechanisms not to work properly. The theory of an inborn vulnerability interacting with an environmental trigger is similar to theories proposed for many other medical conditions. As with many other medical conditions, treatment for bipolar disorder focuses on therapy, medications and making life-style changes to reduce the risk of mood episodes.
What are the symptoms of bipolar disorder?
Over the course of bipolar disorder, four different kinds of mood episodes can occur:
1. Mania (manic episode). Mania often begins with a pleasurable sense of heightened energy, creativity, and social ease-feelings that can quickly escalate out of control into a full-blown manic episode. People with mania typically lack insight, deny anything is wrong, and angrily blame anyone who points out a problem. In very severe cases, there may be psychotic symptoms such as hallucinations (hearing or seeing things that aren't there) or delusions (firmly believing things that aren't true).
2. Hypomania (hypomanic episode). Hypomania is a milder form of mania with similar but less severe symptoms and less impairment. The individual may have an elevated mood, feel better than usual, and be more productive. These episodes often feel good and the quest for hypomania may even cause people to stop their medication.
3. Depression (major depressive episode). In a full-blown "major" depressive episode, the following symptoms are present for at least 2 weeks and make it difficult for you to function:
· Feeling sad, blue, or down in the dumps or losing interest in things you normally enjoy Plus at least four of the following:
· Trouble sleeping or sleeping too much
· Loss of appetite or eating too much
· Problems concentrating or making decisions
· Feeling slowed down or feeling too agitated to sit still
· Feeling worthless or guilty or having very low self-esteem
· Loss of energy or feeling tired all of the time
· Thoughts of suicide or death.
· Severe depressions may also include hallucinations or delusions.

4. Mixed Episode. Perhaps the most disabling episodes are those that involve symptoms of both mania and depression occurring at the same time or alternating frequently during the day. You are excitable or agitated as in mania but also feel irritable and depressed, instead of feeling on top of the world.