Heredity (genetics): Many mental illnesses run in families, suggesting they may be passed on from parents to children through genes. Genes contain instructions for the function of each cell in the body and are responsible for how we look, act, think, etc. However, just because your mother or father may have or had a mental illness doesn't mean you will have one. Hereditary just means that you are more likely to get the condition than if you didn't have an affected family member. Experts believe that many mental conditions are linked to problems in multiple genes -- not just one, as with many diseases -- which is why a person inherits a susceptibility to a mental disorder but doesn't always develop the condition. The disorder itself occurs from the interaction of these genes and other factors -- such as psychological trauma and environmental stressors -- which can influence, or trigger, the illness in a person who has inherited a susceptibility to it.

Biology: Some mental illnesses have been linked to an abnormal balance of brain chemicals called neurotransmitters. Neurotransmitters help nerve cells in the brain communicate with each other. If these chemicals are out of balance or are not working properly, messages may not make it through the brain correctly, leading to symptoms of mental illness. In addition, defects in or injury to certain areas of the brain also have been linked to some mental conditions.

Psychological trauma: Some mental illnesses may be triggered by psychological trauma suffered as a child, such as severe emotional, physical, or sexual abuse; a significant early loss, such as the loss of a parent; and neglect.

Environmental stressors: Certain stressors -- such as a death or divorce, a dysfunctional family life, changing jobs or schools, and substance abuse -- can trigger a disorder in a person who may be at risk for developing a mental illness.

How Is Mental Illness Treated?

A mental illness, like many chronic illnesses, requires ongoing treatment. Fortunately, much progress has been made in the last two decades in treating mental illnesses. Asa result, many mental conditions can be effectively treated withone or a combination of the following therapies :

Medication

Psychotherapy.

Group therapy.

Day treatment or partial hospital treatment.

Specific therapies, such as cognitive-behavior therapy and behavior modification.

Other treatments available include:

Alternative therapies, such as water therapy, massage, and biofeedback.

Creative therapies, such as art therapy, music therapy, or play therapy.

Hypnotherapy.

Electroconvulsive therapy (ECT).

Vagus nerve stimulation (VNS).

Transcranial magnetic stimulation (TMS) is a newer therapy.