02 October 2013

What is depression?

Depression is a medical illness. Everyone feels down or low at some stage, but when these lows last for long periods and affect general functioning and behaviour, the person may be suffering from a Depressive Disorder.

Depression, which must be distinguished from sadness or “the blues”, is a common and legitimate medical illness.

Everyone feels down or low at some stage, but when these lows last for long periods and affect general functioning and behaviour, the person may be suffering from a Depressive Disorder.

Although depression is defined as a disorder of mood, it affects more than just one’s mood and includes symptoms affecting the body (e.g. low energy, sexual dysfunction), thoughts (difficulty concentrating, indecisiveness) and feelings (depression, irritability).

It is a medical illness like high blood pressure, diabetes or heart problems and not a sign of personal weakness. Depression cannot be wished away and sufferers cannot simply pull themselves together, but with appropriate treatment 80% of sufferers will experience relief of symptoms, and up to 60% may recover fully.

Who is affected?

Depressive disorders are common and approximately 6-10% of the population will experience a depressive episode in any given year. More women than men are affected (2:1), with some estimating that as many as one in five women (20%) will experience an episode of depression during any given year. There is however a possibility that depression in males are underdiagnosed because of the structuring of diagnostic criteria. All races and socio-economic classes are affected equally, but it is possible that clinicians may under-diagnose depression and over-diagnose schizophrenia in patients from racial and cultural backgrounds different from their own.

The average age for a first diagnosed episode of major depression is about 40, while for bipolar disorder it is 30. Nearly 50% of patients have onset between the ages of 20-50. Depression can begin in childhood or in later life, but this is less common and tends to present differently in different age groups [e.g. childhood (2%) – apathy; adolescence (5%) – behavioural problems; elderly (25 - 50%) – (physical complaints].

Depressive disorders are more likely in those individuals who are socially isolated and have no close interpersonal relationships or who are divorced or separated.


There are several different types and sub-types of depressive illness, just as heart disease may present in different ways. Three of the more common forms are:

•    Major Depressive Disorder (MDD) – defined as a depressed mood or loss of interest and pleasure in almost all activities for at least a period of two weeks. Several other symptoms must also be present. These include sleep disturbances, appetite disturbances, change in energy levels, difficulties thinking and concentrating, and sexual difficulties. These symptoms interfere with usual behaviour and functioning.
•    Dysthymia – many of the same symptoms as those for a MDD are present, but they tend to be less severe and interfere less with immediate functioning. They are, however, chronic and may continue for years so that the sufferer seldom feels really happy and cannot enjoy life. Due to the long-term impairment of functioning, many do not realise their full potential. Dysthymia can therefore have severe long-term consequences and be severely disabling.
•    Bipolar Disorder – used to be called manic depression. This is much less common than the two previously mentioned depressive disorders and only 2% of the population is affected over a lifetime. Males and females are affected equally. This type of depressive disorder involves episodes of depression and episodes of mania/euphoria. The switches between these two states may be fairly sudden and dramatic, but are more commonly gradual in onset. Both mood states may co-exist – mixed bipolar disorder. During episodes of mania, judgement is often impaired and this can result in socially embarrassing behaviour, sexual indiscretions, excessive spending and unwise business decisions. Bipolar disorder tends to be a chronic, recurring condition and is generally considered to have a poorer long-term outcome than Major Depressive Disorder.
Other types of depressive illness include:
•    Minor Depressive Disorder (same duration, but less severe symptoms than MDD)
•    Recurrent Brief Depressive Disorder (same symptoms as MDD, but episodes last less than two weeks)
•    Premenstrual Dysphoric Disorder (experiencing depressive symptoms that occur during the last week before menstruation for at least one year)
•    Post-partum Depression (depression following childbirth, more severe and of longer duration than transient "Baby Blues")

Depressive Disorders may also be related to drug and alcohol abuse as well as to prescription drug usage (Substance Induced Mood Disorders) and to medical illnesses (Mood Disorder Due to a General Medical Condition).

(Previously reviewed by Dr Piet Oosthuizen, Dept. Psychiatry, University of Stellenbosch, January 2008. Reviewed by Dr Stefanie van Vuuren, Psychiatrist, MB ChB (Stell), M Med (Psig) (Stell), FC (Psych)SA, May 2011)


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Depression expert

Michael Simpson has been a senior psychiatric academic, researcher, and Professor in several countries, having worked at London University in the UK; McMaster University in Canada; Temple University in Philadelphia, USA.; and the University of Natal in South Africa.

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