What are the Causes of Mental Illness?
Although the exact cause of most mental illnesses is not known, it is
becoming clear through research that many of these conditions are caused
by a combination of biological, psychological, and environmental factors.
What Biological Factors Are Involved in Mental Illness?
Some mental illnesses have been linked to an abnormal balance of 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 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 have also
been linked to some mental conditions.
Other biological factors that may be involved in the development of
mental illness include:
- Genetics (heredity): Many mental illnesses run
in families, suggesting that people who have a family member with a
mental illness are more susceptible (have a greater likelihood of
being affected) to developing a mental illness. Susceptibility is
passed on in families through genes. Experts believe many mental
illnesses are linked to abnormalities in many genes, not just one.
That is why a person inherits a susceptibility to a mental illness
and doesn't necessarily develop the illness. Mental illness itself
occurs from the interaction of multiple genes and other factors such
as stress, abuse, or a traumatic event, which can influence, or
trigger, an illness in a person who has an inherited susceptibility
- Infections: Certain infections have been linked
to brain damage and the development of mental illness or the
worsening of its symptoms. For example, a condition known as
pediatric autoimmune neuropsychiatric disorder (PANDA) associated
with the Streptococcus bacteria has been linked to the development
of obsessive-compulsive disorder and other mental illnesses in
- Brain defects or injury: Defects in or injury
to certain areas of the brain have also been linked to some mental
- Prenatal damage: Some evidence suggests that a
disruption of early fetal brain development or trauma that occurs at
the time of birth, for example, loss of oxygen to the brain, may be
a factor in the development of certain conditions, such as autism.
- Other factors: Poor nutrition and exposure to
toxins, such as lead, may play a role in the development of mental
What Psychological Factors Contribute to Mental Illness?
Psychological factors that may contribute to mental illness include:
- Severe psychological trauma suffered as a child, such as
emotional, physical, or sexual abuse
- An important early loss, such as the loss of a parent
- Poor ability to relate to others
What Environmental Factors Contribute to Mental Illness?
Certain stressors can trigger an illness in a person who is susceptible
to mental illness. These stressors include:
- Death or divorce
- A dysfunctional family life
- Living in poverty
- Feelings of inadequacy, low self-esteem, anxiety, anger or
- Changing jobs or schools
- Social or cultural expectations (For example, a society that
associates beauty with thinness can be a factor in the development
of eating disorders.)
- Substance abuse by the person or the person's parents