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Mood Disorders Biological explanations Genetics

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Presentation on theme: "Mood Disorders Biological explanations Genetics"— Presentation transcript:

1 Mood Disorders Biological explanations Genetics
Neurochemical abnormalities

2 Mood Disorders – Genetic
Zubenko et al (2001) Family history – 50% of FD relatives, 25% of SD relatives also had mood disorder Relatives had increased risk of suicide & liver disease McGuffin et al (1996) MZ 46%, DZ 20% MZ concordances substantially inflated in more serious cases

3 Mood Disorders – Genetic
Depression tends to run in families The closer the relationship with a sufferer, the more likely a person will have a mood disorder Genetic evidence is strongest for most severe forms of the disorder Concordance rates also indicate a substantial environmental contribution

4 Mood Disorders - Neurochemical
Abnormality in neurochemicals Too much or too little of some chemicals e.g. serotonin affects the functioning of the brain – this might have an effect on emotion regulation

5 Mood Disorders - Neurochemical

6 Mood Disorders - Neurochemical
Noradrenanaline (NA) Too little leads to depression, too much to mania (catecholamine hypothesis) Serotonin (5-HT) Regulates NA activity, so too little allows abnormal fluctuations in NA (permissive amine hypothesis) Dopamine (DA) Involved in reinforcement, so too little results in anhedonia (dopamine hypothesis)

7 Mood Disorders - Neurochemical
Some evidence (but not all) suggests that mood disorder patients have abnormal levels of NA & 5-HT Might be sensitivity to neurotransmitters that matters, not raw levels in brain Interactions between neurotransmitters are poorly understood – likely to be complex Problems with direction of causality

8 Mood Disorders - Neurochemical
Drugs that alter brain levels of NA & 5-HT are effective in treating depression in about 60% of cases So what about the non-responsive patients? Relapse when drugs are discontinued? Treatment-aetiology fallacy?


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