Although it is very difficult to zero in on the exact causes of mental illness, it is now understood that they are caused by a range of factors.
Genetic causes of mental illness
Having a close family member or friend with a mental illness can increase the risk of developing mental illness. Scientists now agree that many psychiatric disorders tend to run in families, suggesting that susceptibility to mental illness is passed on in families through genes.
It must be noted that an individual may inherit a susceptibility to a mental illness but not develop the illness. Also, having a relative with mental illness does not necessarily mean that other family members will have the illness too.
Mental illness may ultimately be caused by the interaction of multiple genes amongst themselves and with other factors.
Medical causes of mental illness
Having a serious medical condition (e.g., cancer, traumatic brain injury, immuno-infections, or early fetal brain development) may cause mental illness. Deficiencies or defects in certain areas of the brain have also been linked to some mental illnesses.
Psychological causes of mental illness
The psychological makeup of an individual also plays a vital role in causing mental illness. For instance, traits of narcissism, perfectionism, and low self-esteem can increase the risk of developing certain mental illnesses.
Environmental causes of mental illness
A range of environmental factors can cause mental illness. These include, but are not limited to, childhood abuse, trauma, or neglect; loss of a loved one; substance abuse; poverty; financial debt; isolation or loneliness; homelessness; poor nutrition; and severe or long-term stress.