What Are the Various Biological Cause of Depression Flashcards

Hammen (1997): some symptoms are somatic; depression runs in families; antidepressant medication reduces the symptoms of depression; we know certain medical conditions and drugs induce depression. Hammen points out that none of these facts are strong enough evidence for depression having a biological nature of depression.

It is well known that: psychological factors can lead to physical symptoms; patterns of family interaction and the modelling of depressed behaviour can cause patterns of behaviour; the way we think and feel can be passed on through families. Therefore, just because depression can be induced and treated biologically does not mean that depression naturally occurs.

We have long known that children of depressed parents are more vulnerable to depression than comparable children without depressed parents.

Twin studies are the strongest evidence for a genetic element to depression. A study for this is McGuffin et al (1996): they looked at 109 twin pairs with at least one parent being treated for depression: there was a 46% concordance rate in MZ (identical) twins and 20% of DZ (fraternal) twins in terms of those who had also reported suffering symptoms of depression.

The theoreticalv values based on shared genes: 50% for first degree relatives (parents and siblings); 25% for 2nd degree relatives.

In a review of 10 family studies, Gershon (1990) found rates for unipolar depression ranged between 7 and 30% in first degree relatives.

Weissman et al (1984): relatives of a depressive below the age of 20 were 8x more likely to be diagnosed with depression than is they had a non-depressed relative. However, this could be due to life changes and social readjustment during this time.

A strength of these sorts of studies is that it takes potential depressives away from the relatives that might lead them to depression - they can show whether depression is solely biological.

Wender et al found that if an adopted child has depression, members of their biological family are 8x times more likely to be diagnosed with depression than members of their adoptive family.

Hecimovic and Gilliam (2006) found that the 5-HTT gene, linked to the transmission of serotonin, appears to be abnormal in unipolar depressives.

Silberg et al studied the influence of genetic factors and life stress on depression among adolescent girls. Their aim was to assess the role of genes and recent life events. They studied 902 pairs of twins: 182 girls and 273 boys were pre-pubertal in age girls and 171 boys were at puberty. Each completed a standard psychiatric interview to assess depression; life events were measured with questionnaires given out and with an interview with parents. Differences in boys and girls and links to see how genes and life events worked together to cause depression were assessed.

Silberg et al found that, overall, girls suffered more depression than boys - on average they were more susceptible to depression in response to life events. There were wider individual differences among the girls in their response to these life events. 58% of girls who suffered depression after a negative life event also had a twin who suffered depression. This suggests the important role for genes in detemining individual differences in vulnerability to depression in response to life events.

The study supported a role for both genes and environment (in the form of life events) in the development of depression. It gives us an indication as to how genes operates and it seems that, rather than causing depression directly, genetic factors make us particularly susceptible to the depressing effects of life events.

There is not a depression gene but some people are predisposed to being vulnerable to depression when unpleasant thing happen to them.

Kendler et al (1992) used twin studies to explore mild MDD biological links - it was found that there was little difference between MZ (49%) and DZ (42%) and their chances of sharing depression - this suggests that milder depression may have less genetic influence, if any at all.