PY4-Aetiologies of Unipolar

Biochemical:

• Unipolar may be a result of changing levels of a number of neurotransmitters (seretonin, noradrenaline, dopamine)
• Ketty's Seretonin Theory suggests that seretonin controls the levels of other transmitters and that if low levels of serotonin occur, other transmitters (noradrenaline & dopamine) can fluctuate wildly, prodcing unipolar.
• Sertonin - affects mood and sleeping habits. Dopamine - affects psychosis/negative thoughts. Noradrenaline - affects energy levels including movement and lethargy.

Evaluation:

NcNeil and Cimbolic (1986)

- Found major seretonin-by product, is not found in the cerebrospinal fluid of suicidally depressed patients, suggesting it is deficient in depressive's brains.
- Supports, as it shows that low levels of serotonin have an influence on mood and therefore relates to causing depression.

However...

- This research study does not establish a cause-effect relationship; so it is difficult to know whether the levels of serotonin caused the depression or whether depression alters the level of neurotransmitters.

Antidepressants

- Increases the levels of noradrenaline and seretonin to alleviate the symptoms of depression, this supports the influence of biochemical's on mood.

Treatment Aetiology Fallacy

- Mistaken idea that the success of treatment reveals the cause of the disorder.
- If antidepressants work, it doesn't mean that unipolar is caused by the lack of seretonin.

Lag Tim Effects

- Antidepressents increase levels of brain chemicals immediately but not depression.

Genetic Aetiology:

• Suggests a link between genetic makeup and unipolar, and the possibility of the presence of unipolar from genteic vulnerability.
• It is assumed that the more losely related ypu are to someone with depression, the moe likely you are to develop it.

Evaluation:

McGuffin et al (1996)

- 177 pairs of twins, at least on of them had uni0polaf and being treated. They found that 46% of the other MZ twin and 20% of the other DZ twin had also suffered depression.
- Suggest a link, as the MZ twins had a higher chance of the other developing depression, supporting the assumption that the more closely related you are increases the chance.

However...

- Not 100% concordance rate among MZ twins, and infact you are less likely to develop depression if your twin has it. Suggesting other factors, such as environmentl may contribute.

Sample Sizes

- McGuffin's study had a very small sample size because of the limitations of finding suitable twins and families related to unipolar. Therefore the generalisabilty and population validity is low.

Seligman's Learned Helplessness Aetiology:

• Based on classical conditioning principles: learned helplessness occurs when an individual tries but fails to control unpleasant experiences e.g. by trying to overcome an unpleasant experience but results in failure, the individual learns not to overcome things because they believe the attempt is futile, even if another situation can be avoided.

Evaluation:

Reductionist

- Behavioural explanation oversimplified. As it focus is on environmental factors and reduces depression to past experiences.

Seligman and Maier (1967)

- Tested by exposing dogs in hammocks to electric shocks to hind legs which were unavoidable. When exposed to same shocks but in a cage and they had the chance to jump over a barrier to avoid it, the dogs didn't.

- They learned that there is not point in responding again and behaves passively.
- Generalised to humans, it suggests that stressful situations may be unavoidable and LH may occur, which leads to depression including symptoms like lethargy and loss of apetite (the dogs suffered this).

However...

- Results in further studies haven't replicated the same results found in S&M's.
- The LH theory and this study does not consider cognitive reasons for depression.