Currently, mental illness is thought to be caused by a complex interaction of factors, including the following:
- Biologic (physical factors);
- Psychologic; and/or
- Environmental (including social and cultural factors).
Research has shown that for many mental health disorders, heredity plays a part. Often, a mental health disorder occurs in people whose genetic make-up makes them vulnerable to such disorders. This vulnerability, combined with life stresses, such as difficulties with family or at work, can lead to the development of a mental disorder.
Also, many experts think that impaired regulation of chemical messengers in the brain (neurotransmitters) may contribute to mental health disorders.
Brain imaging techniques, such as magnetic resonance imaging (MRI) and positron emission tomography (PET), often show changes in the brains of people with a mental health disorder.
Thus, many mental health disorders appear to have a biologic component, much like disorders that are considered neurologic (such as Alzheimer disease).
However, whether the changes seen on imaging tests are the cause or result of the mental health disorder is unclear.