[Miles E. Drake]

Depression, variously called Melancholia, Depressive reaction or Neurosis and major depressive disorder, has been a major cause of disability and suicide through history, and is the most common mental disorder and the leading psychiatric complaint prompting medical consultation in most series.

The term has been variously used throughout medical history, at times referring to low mood and diminished energy, at other times to various mood disorders now separated diagnostically and most recently to a syndrome of low mood, diminished self-esteem and loss of interest in former pursuits and activities.

CLINICAL FEATURES / SYMPTOMS OF DEPRESSION

The manifestations of major depressive disorder are multiple and pervasive, and its effect on life function and quality of life is comparable to that of diabetes.
The chief characteristic of a major depressive episode is : low mood, with anhedonia or inability to derive pleasure from formerly enjoyable activities and pursuits.

• Rumination over feelings and thoughts of regret, hopelessness, helplessness and unworthiness are common, as are preoccupation with guilt and self-deprecation.
  
• Depressive symptoms may be accompanied by symptoms of psychosis, particularly self-deprecating or –accusatory delusions or less common frightening or menacing hallucinations.
  
• Psychotic depressive episodes or major depression of the melancholic type are often associated with impaired concentration and memory, while social withdrawal, abandonment of former activities, decreased sex drive and interest and preoccupation with death or thoughts of suicide are common.
  
• Sleep disturbance is almost universal, usually early awakening with inability to get back to sleep but also hypersomnolence.
  
• Multiple physical complaints, chiefly digestive ones or related to headache or fatigue, are common, and in developing countries these are the most common presenting symptoms of depression.
  
• Decreased appetite and weight loss are more common than increased appetite and weight gain, and recent cognitive symptoms such as forgetfulness and motor symptoms such as slowness are described, particularly in older depressed individuals.
  
• Either agitated or lethargic behavior may be reported by caregivers of older patients, in whom coexistent physical disorders such as cardiovascular disease, stroke or Parkinson’s disease are more common.
  

Mood may be irritable rather than depressed in children, and personality change, inattention and decreased cognitive performance in school may predominate over depressive feelings.