Distinguish between necessary sufficient and contributory causes of abnormal behavior.

In the framework of modern psychology, abnormal behavior, or a disorder in other words, occurs as a result of different types of causes:

Necessary cause refers to the cause that is necessary for the development of abnormal behavior. Without the presence of such cause, it would not develop. Meanwhile, the cause may occur but outcome is not going to develop from it. Let us take the example of occupational burnout syndrome. It can occur only if the cause of continuous work-related stress is present. Meanwhile, not every individual exposed to continuous work-related stress will develop this syndrome. If sufficient cause is present, individual will always develop abnormal behavior. It is a bulletproof cause that has only one outcome. For example, severe accumulated sleep deprivation will always lead to fatigue, drowsiness and impaired cognition. All truck drivers who are constantly sleep deprived ultimately experience these conditions, which can lead to serious motor vehicle injuries. Contributory cause in its turn contributes to the development of abnormal behavior. It does not cause it directly, nor serves as necessary basis for its development. For example, cannabis consumption have been linked to the greater chance of developing schizophrenia among those individual who already belong to the risk group (people with respective heredity).