What is Depression?

While we all feel sad, moody or low from time to time, some people experience these feelings intensely, for long periods of time (weeks, months or even years) and sometimes without any apparent reason. Depression is more than just a low mood – it's a serious illness that has an impact on both physical and mental health.

Different Types of Depression

Major depression

Major depression is sometimes called major depressive disorder, clinical depression, unipolar depression or simply depression. It involves low mood and/or loss of interest and pleasure in usual activities, as well as other symptoms such as those described here. The symptoms are experienced most days and last for at least two weeks. The symptoms interfere with all areas of a person's life, including work and social relationships. Depression can be described as mild, moderate or severe; melancholic or psychotic (see below).


This is the term used to describe a severe form of depression where many of the physical symptoms of depression are present. One of the major changes is that the person can be observed to move more slowly. The person is also more likely to have a depressed mood that is characterised by complete loss of pleasure in everything, or almost everything.

Psychotic depression

Sometimes people with a depressive disorder can lose touch with reality and experience psychosis. This can involve hallucinations (seeing or hearing things that are not there) or delusions (false beliefs that are not shared by others), such as believing they are bad or evil, or that they are being watched or followed. They can also be paranoid, feeling as though everyone is against them or that they are the cause of illness or bad events occurring around them.

Bipolar disorder

Bipolar disorder used to be known as 'manic depression' because the person experiences periods of depression and periods of mania, with periods of normal mood in between.

Mania is like the opposite of depression and can vary in intensity – symptoms include feeling great, having lots of energy, having racing thoughts and little need for sleep, talking fast, having difficulty focusing on tasks, and feeling frustrated and irritable. This is not just a fleeting experience. Sometimes the person loses touch with reality and has episodes of psychosis. Experiencing psychosis involves hallucinations (seeing or hearing something that is not there) or having delusions (e.g. the person believing he or she has superpowers).

Bipolar disorder seems to be most closely linked to family history. Stress and conflict can trigger episodes for people with this condition and it's not uncommon for bipolar disorder to be misdiagnosed as depression, alcohol or drug abuse, Attention Deficit Hyperactivity Disorder (ADHD) or schizophrenia.

Diagnosis depends on the person having had an episode of mania and, unless observed, this can be hard to pick. It is not uncommon for people to go for years before receiving an accurate diagnosis of bipolar disorder. It can be helpful for the person to make it clear to the doctor or treating health professional that he or she is experiencing highs and lows. Bipolar disorder affects approximately 2 per cent of the population.

Cyclothymic disorder

Cyclothymic disorder is often described as a milder form of bipolar disorder. The person experiences chronic fluctuating moods over at least two years, involving periods of hypomania (a mild to moderate level of mania) and periods of depressive symptoms, with very short periods (no more than two months) of normality between. The duration of the symptoms are shorter, less severe and not as regular, and therefore don't fit the criteria of bipolar disorder or major depression

Dysthymic disorder

The symptoms of dysthymia are similar to those of major depression but are less severe. However, in the case of dysthymia, symptoms last longer. A person has to have this milder depression for more than two years to be diagnosed with dysthymia.

Seasonal Affective Disorder (SAD)

SAD is a mood disorder that has a seasonal pattern. The cause of the disorder is unclear; however it is thought to be related to the variation in light exposure in different seasons. It's characterised by mood disturbances (either periods of depression or mania) that begin and end in a particular season. Depression which starts in winter and subsides when the season ends is the most common. It's usually diagnosed after the person has had the same symptoms during winter for a couple of years. People with Seasonal Affective Disorder depression are more likely to experience lack of energy, sleep too much, overeat, gain weight and crave for carbohydrates. SAD is very rare in Australia and more likely to be found in countries with shorter days and longer periods of darkness, such as in the cold climate areas of the Northern Hemisphere.

The Facts 

Depression in the Australian Community 
  • One million people in Australian currently suffer from depression and 2.3 million suffer from anxiety (1)
  • In any year 10,000 young Australians live with depression (2)
  • Postnatal depression effects 14% of new mothers in Australia (2)
  • The prevalence of depression in an Australian sample group increased in the ten years to 2008 from 6.8% to 10.3% (3)
  • Depression and anxiety affect one in seven and one in four people respectively at some point in their lives (1)
  • Depression will be second only to heart disease as the leading medical cause of death and disability within 20 years (2)

The economic impact of depression
  • Depression-associated disability costs the Australian economy $14.9 billion annually (2)
  • In Australia more than 6 million working days are lost each year (2)
  • Depression costs the Australian community over $600 million each year in treatment costs (2)
Social Impact of Depression
  • The World Health Organization reports that death from suicide accounts for more fatalities than either from armed conflicts globally or the number of people dying from traffic accidents.
  • There are approximately 900,000 suicides a year world-wide, and World Health Organization data show that suicide is now one of the three leading causes of death among people aged 15-34 years
  • Approximately 2000 Australians die from suicide every year. Men are 4 times more likely to die by suicide than women and they use more violent means generally to end their lives (1)
  • In 2010, 1.6% of all Australian deaths registered were attributed to suicide, approximately the same proportion as in 2007 and 2008 (4)
  • Males comprised approximately 77% of Australian suicide deaths for 2010 (4)
Treatment and Care of Depression 
  • Depression is currently the leading cause of non-fatal disability in Australia, with less than 50% receiving medical care (2)
  • In an Australian study, of those people who had any need for care for depression, only 30.8% had all their needs fully met, while the great majority had unmet or partially met care needs (5)


1. Australian Bureau of Statistics, 2008
2. Beyond Blue (

3. Australian and NZ Journal of Psychiatry, South Australian Sample Group, survey period 1998, 2004 and 2008
4. ABS Data released 20th March 2012

5. Perceived need for mental health care and barriers to care in the Netherlands and Australia: Soc Psychiatry Epidemiol. 2011 October; 46(10): 1033-1044

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