Bipolar affective disorder
Bipolar disorder (previously known as manic-depression) is a serious illness and those affected may experience depression lasting weeks or months, alternating with bouts of elation or mania ('highs') of variable duration. For people with elation, who do not have the accompanying depressive episodes, it is referred to as bipolar disorder. Those affected by the illness may have 'normal' mood for months or even years. The mood-swings of bipolar disorder should not be confused with the mood changes that we all experience from time to time. They are much more intense and prolonged and can have a devastating effect on the individual and their relationships. Have a look at the video below by Dr. Diana Cody which looks at Bipolar Affective Disorder in more detail.
This is an on-going form of the illness where those affected may not meet the diagnostic criteria for depression but nevertheless experience chronic low mood, which can last for a period of years and affects their enjoyment of life.
Postnatal depression (PND) is an illness affecting up to 15% of mothers. About one third of these will have developed the symptoms during pregnancy. These symptoms include tiredness, anxiety and irritability but with PND, there may not be strong feelings of sadness or unhappiness. This may mean that those affected don't seek help as they believe it is a result of sleep loss and coping with the demands of a new baby. It is different from the 'Baby Blues' in that these are experience by about 60% of women, usually starting on the third day after birth. Symptoms include feeling tearful and/or irritable for little or no reason. These are due to hormonal changes and for most women last only one or two days but no longer than 10 days. PND generally starts a few weeks after the birth and lasts longer.
This is a severe form of the illness where, in addition to the other common symptoms, those affected may at some time lose contact with reality and experience hallucinations or delusions. Many people experiencing psychotic depression will require hospital treatment at some stage.
Reactive and Endogenous depression
These are old terms based on the supposed causes of the illness which are now rarely used. Reactive or exogenous depression, meaning coming from external factors, was seen as a depression brought on by life events or circumstances. Endogenous meaning coming from within or having no apparent external cause, was believed to have a strong genetic basis i.e. it was hereditary. However now it is generally acknowledged that all cases of the depression are to some degree partly reactive and partly endogenous. The severity of the illness is seen as more important than the cause and so as stated above depression is generally classified as mild, moderate or severe and treated accordingly.
Recurrent depression is where someone experiences more than one episode of the illness. It is quite common, although episodes can vary in severity and individuals may have periods where they are well between episodes.
Seasonal affective disorder
This is a form of depression, which seems to be brought on or made worse by lack of sunlight during the winter months.
This refers to depressive episodes that occur in response to other mental illnesses such as schizophrenia, as a result of alcohol/drug abuse or arising from a physical illness such as a viral infection or Parkinson's disease.
Unipolar depression is an umbrella term for all the types of depression listed below where an individual experiences one, or more, episodes of low mood, loss of enjoyment and/or extreme tiredness sufficient to warrant a diagnosis of depression.