Aetiologies of Depression

Nota:

• MZ Twins share all their genes and grow up in the same environment.

1. McGuffin: Studied 177 probands with depression and found a concordance rate of 46% in MZ twins
   1. 20% for DZ twins
   2. Suggests depression's inherited. However not 100% so environment must play a role

Nota:

• If depression was caused by genetic factors then we would expect it to run in families

1. Gershon: Studied rates of depression and found that. Rate of depression when a first degree relative had depression was 2 to 3 times higher than the GP
   1. Hard to establish cause and effect as they're in the same environment

Nota:

• Can be more effective than family studies as the child goes to/comes from a different environment so GENETIC EFFECTS can be analysed more effectively

1. Wender: Relatives of adopted sufferers were SEVEN times more likely to have had depression
   1. Adopted children who developed depression, their biological parents were EIGHT times more likely to develop it
      1. Lacks generalisability, family lives differ around the world
2. Sometimes children are adopted by families with a similar environment, confuses the issue of genes and environment

Nota:

• We already have a predisposed depression, but we need an event to trigger it.

1. Kendler: Co-twin of a depressed female were more likely to become depressed
   1. Highest levels of depression found in those who were exposed to the most negative life events
2. Wilhelm: 150 Australian Teachers interviewed 5 times over 25 years about negative life events. Those who had these events were more likely to be depressed but even more so if they had short-short form of the serotonin transporter gene
   1. Lacks external validity

Nota:

• The condition of a human or animal that has learned to behave helplessly, failing to respond even though there are opportunities for it to help itself by avoiding unpleasant circumstances or by gaining positive rewards

1. Learned helplessness theory is the view that clinical depression and related mental illnesses may result from a perceived absence of control over the outcome of a situation.
2. Seligman: Dogs, Barriers. Dog would jump over the barrier when he got shocked but when the barrier was raised, the dog realised it was unavoidable. When the barrier was lowered, the dog still did not jump. It had learned to be helpless
   1. This could relate to depressed people, as they see no escape from their depression, so do not try to change it
      1. However, dogs think differently to humans.
      2. However, this lacks ecological validity and mundane realism
3. Abramson: Focused on the thoughts of people with learned helpedness. People respond in a number of ways
   1. Internal/External
      1. Something inside them
      2. Other circumstances, people
   2. Stable/Unstable
      1. Likely to continue in the future
      2. Will probably change in the future
   3. Global/Specific
      1. Applies to a wide range of situations
      2. Applies to one situatuons
   4. Is it the attributions that make you depression, or the depression that causes you to attribute negatively
4. Lewinsohn: Adolescents, over 12 months. Those who attributed negatively at the beginning were more likely to develop depression.

1. Beck's Cognitive Triad

   Nota:

   • Negative view of ourselves > Negative view of the world > Negative view of the future >
   1. Negative schemas cause us to view ourselves, the world and the future negatively
      1. Depressed people pay more attention to the negatives, so find it hard to break out of this pattern
2. A Negative Self-Schema is a packet of thoughts, feeling and knowledge about ourselves.
   1. Develops in early experiences
   2. Once we have a negative self-schema it becomes difficult for us to interpret new information positively

1. Research by Kendler and Wilhelm show a link between genetic predispositions and negative life events
   1. However, both these studies lack external validity.

Nota:

• Comorbidity: the concordance rate of two or more diseases or conditions in the same individual at the same time.

1. Kendler: found a higher concordance rate of depression and anxiety disorder, than just depression alone

1. Lewisjohn found no relationship between negative thoughts and future depression
2. Most evidence suggest negative thoughts are caused by depression

1. Ignores genes and environment

1. However, does the success of the treatment truly find the cause of the conditon

   Nota:

   • Treatment-Aetiology Fallacy