1. Mood Disorders Biological explanations –Genetics –Neurochemical abnormalities www.psychlotron.org.uk

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 www.psychlotron.org.uk

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 www.psychlotron.org.uk

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 www.psychlotron.org.uk

5. Mood Disorders - Neurochemical www.psychlotron.org.uk

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) www.psychlotron.org.uk

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 www.psychlotron.org.uk

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? www.psychlotron.org.uk