Mental illness is common

From studies that have been carried out in several developing countries, we know that severe mental illness is present at about the same level that is found in Western countries.

Around 1 to 2% of the adult population are affected by psychosis. People with psychosis may believe things that aren't real, hear things that aren't there, and have disturbed behaviour (see figure below).

A further 5 to 10% of the adult population suffer from depression at some point in their lifetime. In depression, people have an abnormal level of sadness that doesn't go away. Depression can lead to a person giving up on life and wanting to die (see figure below). If very severe, somebody with depression may even consider killing themselves (suicide).

In addition, around 5-15% of the adult population will suffer from an anxiety illness at some point during their lifetime. Anxiety is when a person worries too much about something, for example their health, their problems, or even what will happen in the future (see figure below).

Added to this large number is the 3 to 6% of the adult population with a serious problem resulting from their excessive use of alcohol or other drugs (see figure below).

Children can also suffer from mental illness; around 1 in 10 children seem to have mental health problems.

In summary, without including childhood disorders, at least 1 in 6 persons will suffer from a mental illness that needs treatment during their lifetime (figure below). Is this more common than you expected?

The table below summarises the frequency of the major types of mental illness in terms of the percentage of the population who are affected.

The frequency of mental illnesses