A number of different mental illnesses involve depression.
Major depressive disorderThis is the most commonly diagnosed depressive disorder. A person with major depressive disorder becomes very low spirited and loses their enjoyment of life. They lack concentration and energy and have changes in their appetite and sleep patterns. Feelings of guilt are also common. Their feelings of hopelessness and despair can lead to thoughts of suicide.
Major depressive disorder can come on without apparent cause, and can develop in people who have coped well with life, who are good at their work and happy in their family and social relationships. It can also be triggered by a distressing event that the person is unable to deal with.
When symptoms of major depressive disorder are fewer and milder, but last longer (for more than two years), the illness is called dysthymic disorder.
Adjustment disorder with depressed moodPeople with this illness are reacting to a distressing situation in their life, such as the failure of a close relationship or loss of a job, but to a greater degree than is usual.
The feelings of depression are very intense and often include anxiety, poor sleep and appetite changes. The time the symptoms last may vary from weeks to years. People with this type of depression often require treatment to help them find ways to cope with the event and overcome their symptoms.
Post-natal depressionThe so-called 'baby blues' affect about half of all new mothers. They feel mildly depressed, anxious, tense or unwell, and may have trouble sleeping even though they are tired most of the time. This type of depression may last only hours or a few days, then disappear.
However, for about 10 percent of mothers this feeling of sadness develops into a serious disorder called post-natal depression. Mothers with this illness find it increasingly difficult to cope with the emands of everyday life.
They can experience anxiety, fear, despondency, sadness and extreme tiredness. Some mothers have panic attacks or become tense and irritable. There may be a change in appetite and sleep patterns.
A severe, but rare, form of post-natal depression is called puerperal psychosis. The woman is unable to cope with her everyday life and can be disturbed in her thinking and behaviour.
It is essential for mother and child that post-natal depression is treated, and very effective treatments are available.
Bipolar mood disorderA person with bipolar mood disorder (previously called manic depression) experiences depressive episodes alternating with periods of mania involving elation, over-activity, irritability, rapid speech, and recklessness. In more serious instances, the person can also have delusions.
For more information, read the brochure What is bipolar mood disorder?
Co-occurring mental health problemsPeople with depression very often experience symptoms of anxiety. For more information on anxiety, read the brochure What is an anxiety disorder?
Harmful alcohol and other drug use often co-occurs with depression. This makes treatment more complex, and effectively managing alcohol and other drug use is important.
Risk of suicide is also heightened for people with depression.