Severe mental illnesses, such as psychosis, depression, epilepsy and disorders that are common in children and elderly people, are collectively referred to as priority mental health disorders (Box 10.1) by the World Health Organization (WHO). The eight conditions listed in Box 10.1 require special focus from the health service, not only because they cause a lot of suffering to individuals, but also because they are treatable or can be modified through treatment. You will learn about them all, either in this study session or in a later one.

Box 10.1 Priority mental health disorders (WHO)

Psychosis: this is the collective name for a group of serious disorders characterised by changes in behaviour (for example poor self-care, restlessness), strange thoughts or beliefs (for example believing that others wish to do the individual harm) and related dispositions. Psychosis is covered in Study Session 13.
Mania: a form of severe mental illness in which a person is excessively happy or irritable (experiences extreme mood swings), appears over-active and sleeps poorly. People with mania have poor reasoning skills (they have difficulty understanding what is good and what is bad), and display excessive self-confidence. Mania is covered in Study Session 13.

Mania is included under psychosis in the WHO list. The two are separated here for clarity.
Depression: this is the most common priority disorder and is characterised by excessive sadness, loss of interest, lack of energy and related symptoms. It is covered in Study Session 12.
Suicide: this will be discussed in more detail in this session and refers to the intentional ending of one's own life.
Abuse of alcohol and other substances: this is covered in Study Session 14 and refers to excessive use of these substances to the detriment of one's health.
Childhood mental disorders: these are covered in Study Session 17.
Dementia: this condition is more common in older people and is characterised by memory problems and broader problems with thinking and understanding. Dementia will be discussed in Study Session 15.
Epilepsy: this is a chronic or longstanding condition caused by abnormal electrical conductions in the brain. In its most obvious form, it is characterised by episodic loss of consciousness and repetitive jerky movements of the body. The various forms of epilepsy are described in Study Session 15.

Methods of assessment for all the conditions listed in Box 10.1 are detailed in their respective study sessions and some general assessment principles are provided in Study Session 11.