Clinical Depression

Clinical depression is a state of sadness, melancholia or despair that has advanced to the point of being disruptive to an individual's social functioning and/or activities of daily living. Although a low mood or state of dejection that does not affect functioning is often referred to as depression, clinical depression is a medical diagnosis and is different from the everyday meaning of "being depressed".

Clinical depression affects about 16 percent of the population on at least one occasion in their lives. The mean age of onset, from a number of studies, is in the late 20s. About twice as many females as males report or receive treatment for clinical depression, though this imbalance is shrinking over the course of recent history; this difference seems to completely disappear after the age of 50 - 55, when most females have passed the end of menopause. Clinical depression is currently the leading cause of disability in the U.S. as well as other countries, and is expected to become the second leading cause of disability worldwide (after heart disease) by the year 2020, according to the World Health Organization.

Diagnosis
The diagnosis may be applied when an individual meets a sufficient number of the symptomatic criteria for the depression spectrum as suggested in the DSM-IV-TR or ICD-9/ICD-10. An individual is often seen to suffer from what is termed a "clinical depression" without fully meeting the various criteria advanced for a specific diagnosis on the depression spectrum. There is an ongoing debate regarding the relative importance of genetic or environmental factors, or gross brain problems versus psychosocial functioning.

Symptoms
According to the DSM-IV-TR criteria for diagnosing a major depressive disorder (cautionary statement) one of the following two elements must be present for a period of at least two weeks:

• Depressed mood, or
• Loss of interest or pleasure in nearly all activities

It is sufficient to have either of these symptoms in conjunction with five of a list of other symptoms over a two-week period. These include:

• Feelings of overwhelming sadness or fear or the seeming inability to feel emotion (emptiness)
• A decrease in the amount of interest or pleasure in all, or almost all, activities of the day, nearly every day
• Changing appetite and marked weight gain or loss
• Disturbed sleep patterns, such as insomnia, loss of REM sleep, or excessive sleep (Hypersomnia)
• Psychomotor agitation or retardation nearly everyday
• Fatigue, mental or physical, also loss of energy
• Feelings of guilt, helplessness, hopelessness, anxiety, or fear
• Trouble concentrating or making decisions or a generalized slowing and obtunding of cognition, including memory
• Recurrent thoughts of death (not just fear of dying), recurrent suicidal ideation without a specific plan, or a suicide attempt or a specific plan for committing suicide

Other symptoms sometimes reported but not usually taken into account in diagnosis include:

• A decrease in self-esteem
• Inattention to personal hygiene
• Sensitivity to noise
• Physical aches and pains, and the belief these may be signs of serious illness
• Fear of 'going mad'
• Change in perception of time

Depression in children is not as obvious as it is in adults. Here are some symptoms that children might display:

• Loss of appetite
• Irritability
• Sleep problems, such as recurrent nightmares
• Learning or memory problems where none existed before
• Significant behavioral changes; such as withdrawal, social isolation, and aggression

An additional indicator could be the excessive use of drugs or alcohol. Depressed adolescents are at particular risk of further destructive behaviors, such as eating disorders and self-harm.

It is hard for people who have not experienced clinical depression, either personally or by regular exposure to people suffering it, to understand its emotional impact and severity, interpreting it instead as being similar to "having the blues" or "feeling down." As the list of symptoms above indicates, clinical depression is a serious, potentially lethal systemic disorder characterized by interlocking physical, affective, and cognitive symptoms that have consequences for function and survival well beyond sad or painful feelings.