Mental illness is remarkably common. The National Institute of Mental Health estimates that 44 million Americans experience a mental disorder each year. Mental illness can arise out of physical injury or disease, genetics, environmental factors and psychological factors. A tremendous number of specific mental illnesses are described in scientific literature, ranging from depression to schizophrenia. This website focuses on three of the most common types of mental disorders: anxiety disorders, depressive disorders and bipolar disorder.

Causes and Conditions

Because the brain is so remarkably complex, and because so many factors can influence how the brain develops from conception to adulthood, it can be difficult to pinpoint the specific cause, or causes, of any particular mental illness. Over the years, however, scientists have revealed through various kinds of studies that certain factors are highly associated with mental disorders.

Click on these links to learn more about the factors most frequently associated with mental illness:

Click on these links to learn more about the most common mental disorders:

Last Revised: June 10, 2014