Types of Depression

The Black Dog Institute believes there are three broadly different types of depression, each with their own features and causes:  melancholic depression, non-melancholic depression, and psychotic depression. There may possibly be a fourth type, atypical depression.

Knowing that there are different types of depression is important because each type responds best to different treatments.  Depression can also be sub-typed into ‘unipolar’ and ‘bipolar’ expressions.

Unipolar depression is the name given when only depressive episodes are experienced. Bipolar depression refers to having highs as well as depressive episodes in between. In the case of bipolar, the depression could be any of the above four types, however researchers at the Black Dog Institute have found that it is most likely to be of a melancholic or psychotic type.

Melancholic depression 
Melancholic depression is the classic form of biological depression. Its defining features are a more severe depression than is the case with non-melancholic depression and psychomotor disturbance (usually showing as slowed or agitated physical movements and slowed cognitive processing abilities).

Melancholic depression is a relatively uncommon type of depression.  It affects only one to two per cent of Western populations.  The numbers affected are roughly the same for men and women.  Melancholic depression has a low spontaneous remission rate.  It responds best to physical treatments (for example, antidepressant drugs) and only minimally (at best) to non-physical treatments such as counselling or psychotherapy.

Non-melancholic depression
Non-melancholic depression essentially means that the depression is not melancholic, or, put simply, not primarily biological. Instead, it has to do with psychological causes, and is very often linked to stressful events in a person’s life, on their own or in conjunction with the individual’s personality style.  Non-melancholic depression is the most common of the three types of depression.  It affects one in four women and one in six men in the Western world over their lifetime.

Non-melancholic depression can be hard to accurately diagnose because it lacks the defining characteristics of the other two depressive types (namely psychomotor disturbance or psychotic features).  Also in contrast to the other two types, people with non-melancholic depression can usually be cheered up to some degree.

People with non-melancholic depression experience a depressed mood for more than two weeks and social impairment (for example, difficulty in dealing with work or relationships).  In contrast to the other types of depression, non-melancholic depression has a high rate of spontaneous remission. This is because it is often linked to stressful events in a person’s life, which, when resolved, tend to see the depression also lifting.
 
Non-melancholic depression responds well to different sorts of treatments (such as psychotherapies, antidepressants and counselling), but the treatment selected should respect the cause (e.g. stress, personality style).

Psychotic depression
Psychotic depression is a less common type of depression than either melancholic or non-melancholic depression.  The defining features of psychotic depression are
an even more severely depressed mood than is the case with either melancholic or non-melancholic depression; more severe psychomotor disturbance than is the case with melancholic depression; psychotic symptoms (either hallucinations or, more commonly, delusions) and strong guilt feelings.

Psychotic depression has a very low spontaneous remission rate.  It responds only to physical treatments (such as antidepressant drugs).

Atypical depression
Atypical depression is a name that has been given to symptoms of depression that contrast with the usual characteristics of non-melancholic depression.  For example, rather than experiencing appetite loss the person experiences appetite increase; and sleepiness rather than insomnia.  Someone with atypical depression is also likely to have interpersonal hypersensitivity (that is, expecting that others will not like or approve of them).

The features of atypical depression include:

• The individual can be cheered up by pleasant events
• Significant weight gain or increase in appetite
• Excessive sleeping
• Arms and legs feeling heavy and leaden
• A long-standing sensitivity to interpersonal rejection.

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Causes of Depression

Unlike some other illnesses or disorders, there is no simple explanation for what causes depression. 

In general, depression is caused by a mixture of ‘pressure’ or ‘strain’, which can be mild or severe, combined with a vulnerability or predisposition to depression, which, too, can range from mild to severe. 

For each type of depression, there are likely to be different mixtures of causes. For psychotic or melancholic depression, physical and biological factors are generally more relevant.  By contrast, for non-melancholic depression, the role of personality and stressful life events are generally far more relevant. 

Genetics
Contrary to the popular view that depression is due to life experiences and/or personality factors, there is strong evidence that genetics are a significant factor in a person’s predisposition towards developing depression.  The genetic risk of developing clinical depression is about 40%. The remaining 60% is due to factors in the individual’s environment.  Depression is unlikely to occur without significant life events, but the risk of developing depression as a result of some such event is strongly genetically determined. 

Biochemical
Our knowledge of the human brain is still fairly limited. Therefore we do not know what actually happens in the brain to cause depression.   It is likely that with most instances of clinical depression, neurotransmitter function is disrupted.  Neurotransmitters are chemicals that carry signals from one part of the brain to the next. There are many neurotransmitters serving different purposes, however three important ones that affect a person's mood are serotonin, noradrenaline and dopamine.

In normal brain function, neurotransmitters jump from one nerve cell to the next, and the signal is as strong in the second and subsequent cells as it was in the first.  In people who are depressed, the mood regulating neurotransmitters fail to function normally, so that the signal is either depleted or disrupted before passing to the next nerve cell.

In non-melancholic depression, it is likely that the transmission of serotonin is reduced or less active, whereas in people with melancholic and psychotic depression, the neurotransmitters noradrenaline and dopamine are more likely to have failed or be functioning abnormally.

Illness
In a simple sense, illness can lead to depression through the lowered mood we can all experience when we are unwell, in pain or discomfort, confined, and less able to do the things we enjoy. Illness can also change the body’s functioning in a way that leads to depression.  Even if the illness isn’t making us feel down, we still end up with a depression. For example:

• It is known that certain cancers can produce a depression – in these cases the person might be quite unaware that they have the disease.
• Certain medical conditions can lead to mania.
• Compromised immune functioning might play a part in the emergence of depression, although further research is needed to establish this link.

Ageing Brain
As we age, our brain's capacity (in terms of general functioning) reduces, while certain neurotransmitters, which influence mood state, can become affected. Some elderly people who are developing dementia may, at some stage (often early on), develop a severe depression for the first time. The depression is commonly of a psychotic or melancholic type and reflects disruption of circuits linking certain basal ganglia and frontal regions of the brain. Sometimes these changes merely reflect an aging process, particularly in people who are vulnerable to this kind of 'wear and tear'.  In others, however, high blood pressure or mini-strokes (often unnoticed by the individual and their family) may contribute.

Gender
Gender is a partial, but incomplete, explanation of why a person develops depression.  Essentially equal numbers of men and women develop melancholic depression.  However, studies have shown that there is a much greater likelihood of women developing non-melancholic depression than men.  There are a number of explanations for this, among them:

• Women are more likely than men to ‘internalise’ stress, thereby placing them at greater risk of developing depression; additionally, women with unsatisfactory marriages or a number of young children are highly overrepresented among samples of depressed people, suggesting a sex-role component or a reduced ability to seek assistance or support.
• Hormonal factors commencing in puberty may account for the increased chance in women of developing anxiety – a precursor to depression – or depression.
• While sex hormone (or biological) differences may create a greater chance among women of developing depression, certain social factors are still needed to come into play before depression will be experienced.

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Stress
It is important to recognise that nearly every individual can be stressed and depressed by certain events.  Most people get over the stress or depression within days or weeks while others do not.

Past and long-standing stresses can increase the chance of an individual developing depression in later years.  An example is an abusive or uncaring parent, which may result in the child developing a low self-esteem and thus being vulnerable to develop depression in adult life. 

Most individuals who develop non-melancholic depression usually describe an important and understandable life event that occurred before the depression started. The events that are most likely to ‘trigger’ depression are ones where the individual’s self-esteem is put at risk, compromised or devalued. For most adults, self-esteem is closely linked to an intimate relationship and other important areas, like work. Thus, the break-up of a relationship or a marriage is a very common trigger for depression.

Other individuals develop depression when they feel a sense of shame, such as when they believe they have not lived up to their own or others' expectations, thus reducing their self-esteem.

Personality
Research at the Black Dog Institute has shown that people with the following personality types are more at risk of developing depression than others:

• High levels of anxiety, which can be experienced as an internalised 'Anxious Worrying' style or as a more externalised 'Irritability'
• Shyness, expressed as 'Social Avoidance' and/or 'Personal Reserve’
• Self-criticism or low self-worth
• Interpersonal sensitivity
• Perfectionism, and
• A 'self-focused' style.

Those who are high on the first four factors are at distinctly greater risk of depression, especially non-melancholic depression.

 

Self Testing for Depression

The following is a self-test developed by the Black Dog Institute for identifying possible symptoms of clinical depression. Please note that while great care was taken with the development of this Self-Assessment Tool, it is not intended to be a substitute for professional clinical advice. While the results of the Self-Assessment Tool may be of assistance, users should always seek the advice of a qualified health practitioner with any questions they have regarding their health.

Please consider the following questions and rate how true each one is in relation to how you have been feeling lately (i.e, in the last two to three days) compared to how you usually or normally feel.

	Not true	Slightly true	Moderately true	Very true
Are you stewing over things?
Do you feel more vulnerable than usual?
Are you being more self-critical & hard on yourself?
Are you feeling guilty about things in your life?
Do you find that nothing seems able to cheer you up?
Do you feel as if you have lost your core & essence?
Are you feeling depressed?
Do you feel less worthwhile?
Do you feel hopeless or helpless?
Do you feel more distant from other people?

This test is available on the Black Dog Institute website:
www.blackdoginstitute.org.au/public/depression/howtotell/selftesting.cfm 

Please undertake the test online to obtain a score.

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