1. One of the primary psychosocial factors in depression is , including significant negative life events and chronically stressful circumstances (e.g. Brown & Harris, 1989).

2. In bipolar disorder, depression alternates with periods of , which is virtually the polar opposite of depression.

3. The most common and straightforward of the anxiety disorders are specific fear and avoidance of a particular object or situation (e.g. dogs, heights, flying).

4. disorder is characterized by unwanted, persistent, intrusive, repetitive thoughts and ritualistic, repetitive behaviours.

5. Experiencing a traumatic event can lead to has examined the contribution of genetic and environmental factors to human behaviour.