... experience hallucinations or delusions. Other symptoms include; disturbed thinking, apathy, social withdrawal, anhedonia and possible suicidal thoughts. A biological explanation for depression is the genetic explanation. This theory suggests that you are more likely to suffer from depression if you have a relative who as also suffered from depression. For example, monozygotic twins and dizygotic twins has a higher risk than the general population of developing, particularly bipolar if their paired twin had the disorder. Research by Allen (1976) supported this theory when he conducted a study using monozygotic and dizygotic twins. Allen found that for major (unipolar) depression the mean concordance rate for MZ twins was 40 per cent whilst for DZ twins it was only 11 per cent. In comparison, for manic depression the mean concordance rate for MZ twins was 72 per cent, whereas, it was only 14 per cent for DZ twins. In addition, Wendler et ...

See this essay or coursework document in full right now