Everyone has mood swings from time to time; feeling high and feeling low are part of life.
It is only when these moods become extreme and interfere with personal and professional life that Bipolar Disorder may be present.
The term “bipolar disorder” is used to describe patterns of manic or hypomanic behaviour (with elevated, expansive or irritable moods) that may or may not alternate with episodes of clinical depression. The word “hypomania” comes from the Greek and means “less than mania”. Occasionally, people show a mixture of both high and low features at the same time, or switch during the day, giving a mixed picture. Bipolar disorder is thought to be primarily caused by biological factors. It is strongly inherited.
It is now common to distinguish Bipolar I and Bipolar II disorders from one another, but distinctions between the two are not clear-cut, whether examined in formal diagnostic manuals or considered more informally in clinical practice . In general terms, Bipolar I disorder corresponds to the earlier term “manic depressive illness”. Here, episodes of highs or lows are more severe and persistent, functioning is impaired and psychotic features may be present. In the past, people with severe bipolar disorder may have been admitted to an asylum where they could have remained manic for many months or depressed for many years and then spontaneously remitted, indicating that there is a pattern to even the most severe expressions of the condition.
Bipolar II is less severe (so that highs are more likely to be described as “hypomanic” rather than “manic”); it is not usually associated with psychotic features and tends to be briefer . The North American DSM-IV diagnostic manual specifies that hypomanic episodes must last at least four days, but many researchers and clinicians are confident that some individuals with true Bipolar II can have highs and lows lasting hours rather than days. The diagnostic manuals generally rule that mood and behavioural changes must be evident to others (e.g. family members) but there are many people with true bipolar disorder (I and II) who fail to show observable features – even when psychotic – so that imposing “observable change” may miss some individuals. The term “mixed state” refers to times when individuals meet the criteria for both manic and depressive episodes.
To friends and family members, Bipolar II may appear to be merely normal mood swings or a reflection of personality style. Certainly, mild expressions can be very difficult to distinguish from a normal volatile or cyclothymic personality style. There are many people who swing from being the life of the party to being quiet, uncommunicative and even grumpy as part of their personality style and not because they have a bipolar disorder. Personality, however, tends to be persistent over time. By contrast, questioning will usually identify an onset or pattern change for those with true bipolar disorder, although we now recognise that bipolar disorder can also be present in quite young children.
We used to think that manic-depressive illness affected about 1 per cent of the population. More recent epidemiological data suggest that the lifetime chance of Bipolar I is about 1 percent, but the lifetime chance of Bipolar II could be up to 10 percent of the population. Such a high percentage could reflect definitional or diagnostic error (falsely diagnosing bipolar disorder when it does not exist), but The Black dog Institute’s view is that Bipolar II is common and that its rate may have risen considerably in the community in the last decade.
Approximately 5 percent of those suffering bipolar disorder experience only highs. However, the great majority of people with the disorder alternate between highs and lows and, commonly, experience intervals of quite normal mood states in between episodes. Each individual tends to have a distinct pattern. For instance, some people with bipolar disorder might have only one episode every decade, while others may have daily mood swings.
Before any individual settles into their general mood swing “pattern”, atypical patterns may be observed, particularly in adolescents. Thus, some may develop anxiety or eating disorders, or even have schizophrenia-like conditions for several years, before the more typical pattern takes shape. A family history of bipolar disorder can then be very helpful in establishing whether an atypical presentation is a variant or a forerunner of bipolar disorder.*