Biological

Question 1

Genetic explanation - family studies?

Answer 1

• Proband (person with disorder who’s relatives are investigated) identified, family members studied.
• Winokur found rate for unipolar = 10.4% for first degree relatives of probands, compared to 4.9% of controls’ relatives.

Question 2

Genetic explanation - twin studies?

Answer 2

• MZ twins share 100% genetic makeup so should be higher than concordance for DZ twins who share 50% DNA if mood disorders are due to inheritance.

* McGuffin...
214 twin pairs, one had depression.
Concordance for MZ = 46%
Concordance for DZ = 20%
Conclusion - genetics play a part in mood disorders as this is higher than depression rate in general population and the more similar the DNA is, the higher the concordance. 

• Concordance for bipolar disorder in MZ twins = 70%, DZ only 23%

Question 3

Genetic explanation - family studies AO2

Answer 3

• does not isolate nature from nurture. Being reared by a depressed relative means environmental factors can’t be ruled out (stressful family environment).

Question 4

Genetic explanation - twin studies AO2

Answer 4

• Twins raised in more similar environments than ordinary siblings - explains why DZ concordance higher than normal siblings concordance
• adoption studies would separate nature and nurture, but very limited samples in this area of study
• searches for a particular gene responsible for depression is difficult because it is heterogeneous (has many subtypes)
• suggested that genes and environment interact, and that genes determine how susceptible someone is to effects of life events

Question 5

Neurochemical explanation?

Answer 5

• the limbic system is linked to ANS, endocrine system and other parts of brain by neurotransmitter pathways. In the synaptic cleft, neurotransmitters such as seretonin are reabsorbed or destroyed (reuptake). Depression results from too little, mania from too much.

Question 6

Neurochemical explanation AO2

Answer 6

• Antidepressants immediately increase neurotransmitter levels but the symptoms sometimes takes up to 12 weeks to be alleviated.
• most recent research suggests that it is not as simple as increasing neurotransmitter levels and that interaction between various neurotransmitters occurs.

Question 7

Brain structure and functioning?

Answer 7

• strokes have affected the frontal lobes (in the limbic system) in the brain and led to depression, implying that the limbic system, responsible for emotions, is implicated in depression.
• MRIs have found structural abnormalities in frontal lobes of brain, such as lower frontal lobe volume.
• Henrique and Davidson used EEG and discovered hyperactivation in 15 frontal lobes compared to controls.

Question 8

Brain structure and functioning AO2

Answer 8

• diathesis stress suggests that frontal asymmetry are more vulnerable to depression if exposed to lots of environmental stress.
• cause and effect