Depression and Depressive Disorders

The meaning of the word “depression” varies widely. Some people may say they are depressed when they have a bad day, but the mood passes by the next day; this situation would not be classed as depression in a clinical sense. For others, though, feeling unhappy, “down”, or “low” may persist for weeks, months, or even years, and other symptoms may develop along with it.

The low mood associated with depression can range from a mild form, where people still lead a normal life (although the depression makes that harder and less enjoyable) to a severe form, which can be life-threatening, because people are at risk of suicide. At the very least, severe depression has a major and sometimes lasting impact on the person’s life, work, and relationships.

Because there is sometimes a sense of failure or serious mental illness associated with the term “depression”, people will often not admit to feeling depressed. Rather, they may acknowledge feeling unhappy, sad, or low. They may talk about not having interest in things anymore, or feeling tired most of the time.

To decide if someone is “clinically depressed,” a doctor or mental health professional will focus on the symptoms the person is feeling. In order to be classified as “depression”, and in order to distinguish the low mood from other mood problems and from normal, everyday experiences and problems, the clinician will ask the person about core features (which are essential for a diagnosis of depression) and associated features: additional symptoms, some of which the person will need to have in order to meet the criteria for depression.

Core and associated features 

Core features include a lowered mood and a lack of interest or pleasure in usual activities. Either one or both of these must be present for a person to be diagnosed as depressed.   As well as the two core features, there are additional symptoms which constitute a clinical finding of depression. These are either physical, psychological, or social features:

Physical features:

  • Disturbed sleeping: waking in the night or earlier than usual, or sleeping too much
  • Loss of appetite or overeating; changes in weight
  • Tiredness or ongoing lack of energy
  • Aches and pains which are not explained by medical diagnoses of problems
  • Loss of libido
  • Either markedly slowed movement, or increased agitation and restlessness

Psychological features:

  • Feeling unhappy or sad or having a low mood
  • Experiencing a loss of confidence or self-esteem
  • Feeling guilty or self-blaming
  • Being unable to enjoy things like before
  • Feeling that things won’t improve in the future
  • Pessimism or sense of hopelessness
  • Thoughts of self-harm or suicide

Social function features:

  • Poor concentration and/or memory
  • Difficulties managing work, family responsibilities or other usual activities Irritability or more frequent arguments with people in the person’s life
  • Not wanting to see people or do things
  • Frequent visits to the doctor (Haddad, M., Buszewicz, M., & Murphy, B., 2010).

Depression, also called a “major depressive episode”, is classified as mild, moderate, or severe, or as “dysthymia”, according to the following:

Mild depression: At least two core symptoms and at least two additional symptoms; the person has some difficulty with ordinary activities, but can still do them.   Dysthymia: Mild depression for more than two years.

Moderate depression: At least two core symptoms and at least three or four additional symptoms; the person has a fair amount of difficulty carrying on with normal work and social activity.

Severe depression: Two core symptoms, and at least four or five additional symptoms, some of which are severe. The person shows considerable distress and agitation (or else slowing), and is unlikely to be able to continue with their normal activities (Haddad et al, 2010).

The different types of depressive disorders

Mental health professionals distinguish between several different types of depression. The main ones are:

Major depressive disorder: As described above, an episode of depression may be referred to as “major depression”, “clinical depression”, “unipolar depression”, or just “depression”. The person would experience the symptoms from the core and associated features lists (above) most days for at least two weeks, and they would generally interfere with his or her social relationships and work. Dysthymia is included in this category of major depressive disorder.

Bipolar disorder: Formerly known as “manic depression”, bipolar disorder is characterised by periods of depression alternating with periods of mania, during which the person seems to have limitless energy, need very little sleep, talk fast, have difficulty focusing, and do unwise things such as give away the family silver or rack up huge debt on credit cards. The person may have normal moods in between the mania and the depression.

Psychotic depression: This depression occurs when people lose contact with reality. People may believe that they are being persecuted or punished.

Post-partum (postnatal depression): After women have given birth, the hormonal and physical changes in their bodies plus the new responsibilities of caring for the baby put them at higher risk for depression. While the symptoms of “baby blues” are the same as those for “regular” depression, the stakes are higher in that being depressed may significantly interfere with mothering, and with mother-child bonding.

Seasonal affective disorder (SAD): There is a higher incidence of this depression in late autumn and winter, and also in extreme northern countries, such as those of Scandinavia, where there is very little light during the months of winter. Caused by a lack of sunlight, people with this form of depression lack energy, sleep too much, crave carbohydrates, and generally are at risk of weight gain.

Melancholia: In this type of depressed mood, a person may awaken early, lose weight, become very slow in movements, and feel guilty. It feels different from normal sadness, and is a more biological form of depression (Jorm, A., Allen, N., Morgan, A., & Purcell, R., 2009; Haddad et al, 2010).  Often people diagnosed as depressed will be suffering from an anxiety disorder as well.

This article is an extract of the Mental Health Social Support Specialty “Supporting Those With Depression Or Anxiety”. For more information on MHSS, visit  


  • Haddad, M., Buszewicz, M., & Murphy, B. (2010). Supporting people with depression and anxiety: A guide for practice nurses. University College London, MRC General Practice Research Framework.
  • Jorm, A.F., Allen, N.B., Morgan, A.J., Purcell, R. (2009). A guide to what works for depression. beyondblue: Melbourne.