What causes mental illnesses, nature or nurture?
Short answer: both. Many mental illnesses are genetic. The most heritable is bipolar illness. About 80 percent of diagnosed individuals are born with the genes for bipolar illness. When you consider that some individuals born with the genes for bipolar disorder never develop symptoms, the role of environmental factors becomes clearer.
We know two significant environmental factors are:
- child abuse and neglect, and
- early substance use.
Early marijuana use in particular is linked to schizophrenia. Other environmental stress factors include bullying, loss of significant relationships, and trauma.
Many mental illnesses are genetic. The most heritable is bipolar illness. About 80 percent of diagnosed individuals are born with the genes for bipolar illness.
Epigenes are a bridge between nature and nurture. Epigenes are genetic information upstream from genes that change day-to-day based on what goes on in someone’s life. Environmental stress changes epigenes. Downstream, those changes may cause a gene to “turn on” or to stabilize as “off.” For someone who has just lost a spouse, that chain reaction can result in a mental illness.
What other factors may play a role in the development of mental illness?
New research is exploring the link between mental illnesses and increased inflammation in the body caused by a “revved up” immune system.
Research is exploring the link between mental illnesses and increased inflammation in the body caused by a “revved up” immune system.
Inflammation results from many conditions – prenatal infections, medical problems like cancer or lupus, or genetics that “wire” someone with a hyper-reactive immune system from the start.
We are beginning to use C reactive protein (CRP) to determine the amount of inflammation someone has in their system. The more inflammation someone has, the harder it is to treat certain mental illnesses.
Patients with elevated CRP levels may require a different treatment approach, and the use of anti-inflammatory medications is
showing some promise in research studies.
Are the effects of mental illnesses limited to the brain?
The prevailing theory is that immune system aberrations affect the health of all of our organs, including our brains. That’s why people with mental illness, in addition to their psychiatric symptoms, also experience medical conditions that result in decreased life expectancy when matched with the general population for all other factors.
What does this mean for mental health treatment?
To improve health for someone with mental illness using the best evidence-based treatment, you have to go beyond the brain.
We know eating carbs or empty calories causes an insulin spike, which increases inflammation. We also know that exercising specific muscle groups and meditation decreases inflammation. So diet, stress reduction, and exercise become important for improving mental and physical health.
Promising treatment strategies are in the pipeline, including methods to influence genetic expression, regulate the immune system, reduce inflammation, and counteract the effects of environmental stress. We are just beginning to understand the important intersections of our brains, bodies, and environment.