Aetiologies of Depression

Aetiologies of Depression

1. depression - mood disorder; low emotional state characterised by significant levels of sadness; lack of energy and self-worth, and feelings of guilt

2. bipolar = extreme highs & lows, unipolar = just extreme lows

   • 90% of depressive people have unipolar

3. Biological: Genes

   • Twin studies
     • average rate of depression is 5%, so would expect identical twins to have a higher CR
     • McGuffin (1996) - investigated the CR of depressive twins; found 46% CR for MZ and 20% CR for DZ
       • suggests that depression has a heritable component
   • Adoption studies
     • Wender (1986) - biological relatives of adopted sufferers of depression are about 7x more likely than their adopted relatives to have had major depression
       • however, can't generalise as not everyone is adopted
     • children are often placed in adopted homes that are similar to their birth family
       • confuses the issue of genes and environment
     • if depression was completely due to genetic factors, then the CR would be 100%
   • Comorbidity
     • a relationship between depression and other psychological conditions
     • Kendler (1992) - a higher incidence of mental disorders in twins when looking at depression and generalised anxiety disorders rather than depression alone

4. Psychological: Cognitive Theories

   • Learned helplessness
     • Seligman (1975) - first discovered learned helplessness in his experiments on animals; dog was placed into a cage where one side was an electrified floor; dog would receive a painful shock through the floor and would quickly learn that to escape the shock he could jump over the barrier; however if the barrier was too high for the dog to jump then the dog soon accepted that the shocks were unavoidable and passively accepted the shocks; when the barrier was lowered again and escape became possible, the dog still did not try to escape
       • they had learned to be helpless
     • Seligman argued that this is what happens in depressed people
       • people experience several negative life events, feel that they can't escape, and learned to cope with it in that way
     • however, animals used so can't generalise and ethical issues
     • Abramson (1978) developed on learned helplessness; stated that people respond to failure in a number of ways
       • attribute the failure to an...
         • internal cause (something within them such as personality / skill)
         • external cause (other people / circumstances)
       • cause of the failure is either...
         • stable (likely to continue)
         • unstable (might easily change)
       • attribute the failure to a...
         • global cause (applying to a range of situations)
         • specific cause (applying to one situation)
       • people with learned helplessness = internal, stable, specific
   • Beck's theory of depression
     • Negative self-schema - negative feelings and info that we have about ourselves
       • once we have a negative self-schema, it becomes difficult for us to interpret any new info about ourselves positively
     • when a person encounters a new situation that resembles the original conditions when the schemas were learned, they will interpret it negatively
     • Beck's cognitive triad - negative self-schemas cause us to view ourselves, the world, and the future negatively
       • however, Lewinsohn (1981) concluded that there was no relationship between negative thoughts and irrational beliefs and future depression
   • a strength - therapies based on cognitive assumptions are quite successful for depression