2 Types – Genetic and Biochemical
Genetic – depression seems to run in families and a number of studies have shown a correlation between the biological closeness of the relationship and the likelihood of developing depression. Biochemical imbalances in neurotransmitters cause depression; most notably noradrenalin, serotonin according to the permissive amine theory is a controller and dopamine. Interruption in the transmission of nervous impulses
Hormones – high levels of cortisol – overactive pituitary adrenal response
AO2-Genetic Studies
Gershon (family study)
D – reviewed 10 family studies of depression in first and second degree relatives
F – depression in first degree ranged between 7-30% higher than expected
S - if younger people in family diagnosed with depression, the likelihood hood is that their relatives have also had episodes
E – genetics or environment? Family studies often inclusive results.
McGuffin et al
Concordance rate of 46% with MZ and 20% DZ
Bierat 2662 twins MZ 36-44% concordance
Genetics or Environment playing the larger role?
AO2 – Biochemical – Teuting
D – compared urine of depressed patients and control group
F – low levels or noradrenalin and serotonin in depressed patients
S – abnormal levels = depression
E - neurotransmitters cant be measured directly unreliable, cause and effect, may just be an overall imbalance
Hormone - Nemeroff
F- enlarged adrenal glands in people with major depression compared to control
E - cause and effect, lifestyle
Ogilvie- genetic and neuro
D – Cells use a gene called SERT to make serotonin transporter protein. How many repeats on the DNA in control and depressed group.
F – control 10-12 repeats depressed only 9
S – genetic flaw in how they produce serotonin so they make less
General Evaluation
Schildkraut- too low noradrenaline =depression to high = mania. This supports Bunney’s findings of fluctuation in bi polar suffers
Anti-depressants work.