The exact cause of most mental illnesses is not known, but research suggests that a combination of the following factors may be involved.
- Heredity (genetics): Mental illness tends to run in families, which means the likelihood to develop a mental disorder may be passed on from parents to their children.
- Biology: Some mental disorders have been linked to special chemicals in the brain called neurotransmitters. Neurotransmitters help nerve cells in the brain communicate with each other.
- If these chemicals are out of balance or not working properly, messages may not make it through the brain correctly, leading to symptoms. In addition, defects in or injury to certain areas of the brain also have been linked to some mental illnesses.
- Psychological trauma: Some mental illnesses may be triggered by psychological trauma, such as
- severe emotional, physical or sexual abuse;
- an important early loss, such as the loss of a parent;
- Environmental stress: Stressful or traumatic events can trigger a mental illness in a person with a vulnerability to a mental disorder.