What are Mood Disorders?

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When Moods Become Disordered

It’s not uncommon for us to use words that have a variety of meanings and interpretations. Mood, is one such example. We might use the term to reflect a particular inclination as in, ‘I’m in the mood for a curry’, or we might use it more broadly as in, ‘the mood of the nation’. Even so, the use of the word conveys some kind of emotion and reflects a state of mind. Our moods also tend to be relatively temporary. Good moods can switch to bad in a few moments and laughter to tears, so the question is, if these constitute normal moods, what are mood disorders?

Whether you’re a person with a relatively stable temperament or someone who is ‘moody’, the chances are you fit within the bounds of mood normality. If however your moods hinder your ability to function, or cause you significant personal discomfort, then the threshold between mood order and disorder may have been crossed. Two of the key ingredients for defining a mood disorder are firstly that the mood appears for no apparent reason and secondly it persists over a long period of time and pervades every aspect of your life.

Extremes of Mood

Central to mood disorders are the emotions of depression and mania. These are two extremes of mood, although depression is about 10 times more common than mania. Depression also occurs in nearly all cases of mood disorder. It affects all social classes and all ethnic groups and is fast becoming the leading form of disease in the Western world. It is estimated that around 17 percent of all adults in the world will experience an episode of severe depression at some point in their lives (Kessler et al., 2005) and whilst some will recover within six weeks to a year, most will have at least one episode of depression later in life.

The symptoms of depression affect emotions, thought processes, behavior and physiology. The clearest symptom of depression involves the emotions, most notably intense sadness, dejection, unhappiness and anxiety. However, thought processes and motivation also suffer through lack of interest in things previously found pleasurable and the drive to only become involved in the most modest activities. With depression comes low energy, low libido, slow and heavy movements and neglect of personal appearance. Sleep disturbances are common and many depressed women find their menstrual cycle disrupted. Appetite is frequently poor although some people turn to comfort eating.

In stark contrast to depression the symptoms of mania are characterized by expansive, grandiose and persistently elevated moods. This is a feature of bipolar disorder, so-called because, in most people with the disorder, symptoms include mania as well as depression, although symptoms of bipolar depression may differ somewhat. Like depression, emotions, thought processes, behavior and physiology are affected. The path to mania is usually preceded by a stage of elevated mood, energy and enthusiasm, called hypomania. Some people peak at this stage whilst others move to a state of mania. During mania everything about the person is on overdrive. Thoughts race, speech is pressurized and often disjointed and attention is constantly switching from one thing to the next. Behavior is often quite disruptive during mania and can result in high agitation and aggression. Hallucinations and delusions may appear and as a result the person may engage in very risky forms of behavior that threaten themselves and the people they come into contact with.

Why Moods Remain a Puzzle

This article began by posing the question, what are mood disorders? Various factors are being revealed as possible candidates for the cause of depression and bipolar disorder; the puzzle is the extent to which they act in isolation or collaboration. Some mood disorders appear to have a strong cognitive component (Beck, 1974) and this is evidenced by the positive effects found with cognitive therapies in unipolar depression especially. In the case of bipolar disorder the effective use of lithium demonstrates a strong biological component. However, the factors that initiate mood disorders may be different in different people. Low serotonin levels, for example, can lead to the symptoms of depression. In other cases a severe emotional trauma or loss can lead to depression and this can also influence the neurological activity associated with depression. So, whether depression and bipolar disorder represent two distinctive conditions, or are two faces of the same coin, has yet to be established.


Beck, A.T. (1974). The development of depression: a cognitive model. In R.J. Friedman & M.M. Katz (eds), The psychology of depression: contemporary theory and research. New York: Wiley.

Kessler, R.C., Chiu, W. T., Demler, O., & Walters, E.E. (2005). Prevalence, severity, and comorbidity of 12-month DSM-IV disorders in the National Comorbidity Survey Replication. Archives of General Psychiatry., 62, 617-627.