Most people lead a normal life when they are well. The cause is unknown. There may be an inherited component because it tends to run in familites, however in some cases there is no family history. It may also be a chemical change which interferes with the messages which are sent to the brain. In some people it is worse in times of stress and in different seasons of the year.
Early diagnosis is important so that correct treatment can be started at once.
You must seek medical advice even if you feel you don't want to. It is not your fault that you have this illness and talking about your symptoms is the best first step. Most people with manic depression find their lives are improved by taking medicines called mood stabilisers. These are usually drugs that control your depression and keep you calm. You may need to be on medication for a long time.