Biological explanations of depression

Genetic explanation;

Findings from twin, family, adoption and gene mapping studies suggest a genetic component in depression, making some individuals more vulnerable than others.

• Sevey et al (2000) found a concordance rate for bipolar disorder of 69% in identical twins, but only 20% in non-identical twins. 
• Wender et al (1986) found that adopted children who developed depression were more likely to have a biological parent with the disorder, even though adopted children are raised in different environments, implying that biological factors are more important than environmental ones.
• Caspi et al (2005) used gene mapping to find a…