In any 12-month period, 20% of the population will experience a mental health problem. The lifetime prevalence of depression is one in four for women and one in eight for men; anxiety disorders affect 10–15% of people every year and the rate of schizophrenia is one in 100. Among children, 5% will develop attention deficit hyperactivity disorder (ADHD) and 20% of adolescents will develop a mental health problem in any one year. Common disorders include alcohol and substance abuse and bipolar illness. It is hardly surprising that almost every family will be affected by mental illness, yet only a fraction of those with a mental health problem will be treated.