Stress-Vulnerability Model
There are many theories of causation of depression. These include biological, psychological and social factors. Each theory is backed by solid evidence, but it can be difficult to know, in the case of an individual, which factors in particular are most relevant to them.
It is therefore useful in each case to consider the broad range of potential biological, psychological and social causes. The "Stress-Vulnerability Model" (Neuchterlein & Dawson 1984) is a useful concept of: