Clinical Characteristics

DSM IV – for major (unipolar) depression, 5 of the following should occur nearly every day for at least 2 weeks:

  • Emotional symptoms – sadness, depressed mood, loss of appetite, loss of motivation for usual activities.
  • Somatic symptoms – insomnia/hyperinsomnia, weight loss/gain, tiredness.
  • Cognitive symptoms – negative self-concept, low self esteem, apathy, self-blame, lack of concentration, recurring thoughts of suicide and death.

For manic (bipolar) depression:

  • Emotional symptoms – mania (elation, euphoria, unjustified high self-esteem, talkativeness).

10% of males and 20% of females suffer from depression and 90% of that is unipolar. Unipolar depression is either reactive or endogenous.

Egeland et al research done with the Amish in Pennsylvania showed that about 80 members of the same family had depression and this was thought to be caused by a mark on chromosome 11.  However, this research has not been supported.

Wender adopted children are 8 times as likely to become depressed.

Allen concordance rates for depression between twins were greater for MZ twins than for DZ twins.  The rates were also higher for bipolar depression than unipolar depression.  Supported by Bertelsen et al.

Biochemical Explanation

  • Neurotransmitters from the catecholamine/monoamine group e.g. serotonin, noradrenalin and dopamine cause depression.
  • Antidepressant drugs – monoamine oxidase inhibitors increased levels of serotonin (serotonin agonists).  Manic depressants have higher levels of serotonin, so they need lithium which works as an agonist.
  • Serotonin has a knock-on effect on noradrenalin and dopamine.
  • Treatment aetiology fallacy (Macloud) – just because drugs successfully tackle depression by treating serotonin levels doesn’t mean that serotonin is the cause.

The Cognitive Explanation

  • Depression is caused by negative thought patterns.
  • If you attribute failure to an unstable cause you believe it is going to persist.
  • Global/specific cause – if it is a global cause, you will fail in many situations.
  • The cognitive triad (Beck and Clark):
  • Beck’s depression inventory – scores for sadness.  Most college students would get about ¾.
  • However, the questions were things like “have you ever considered killing yourself?” which would make a depressed person feel worse.
  • Also people don’t just get depressed because of failures; it could also be because of loss.

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