Nature vs. Nurture and the Effects of Mental Illness

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Article written by Eric Johnson

Mental illness affects an estimated 57 million people in the U.S., yet there is still a lot we don’t know or understand about the ways a person can be affected. When it comes to the cause of mental illness, scientists have studied for decades to try and find out whether genetics play a definitive role, but they are still coming up short. The truth is, many believe that genetics does have something to do with mental illness, but that environment and events are just as important.

If a person displays signs of schizophrenia, depression, or bipolar disorder, one of the first things a doctor does is check the family history, as the chances are good that at least one family member was diagnosed with it at some point in their lives. However, one study in the U.K. showed that pregnant women who had a major stress event–such as the loss of a loved one–during the first few months of pregnancy were more at risk for their child having schizophrenia.

“It is not a question of genes versus environment. It is a question of how genes interact with whatever the environmental factors might be. And that is probably true of all of the disorders that we call mental illness,” said Dr. Thomas Insel of the National Institutes of Mental Health.

Substance abuse has also been closely linked to mood disorders such as depression, along with suffering trauma during childhood, losing a child or parent, enduring sexual or physical abuse, living in a dysfunctional home, or living with extreme stress. These events and behaviors can exacerbate mental illness that may have already been present, or they can mask the illness, making it harder to diagnose properly.

Studies have shown that common variants in genes can contribute to both schizophrenia and bipolar disorder, and that neither of them are caused by one specific gene, but rather a combination. Doctors say that it’s important to remember that genes can change after birth, as well, meaning even if a person isn’t born with a particular gene variant, they might still have the genetic cause.

“It’s also important to know that even if you don’t inherit a gene for mental illness, you can still have a genetic cause. Genes can alter after birth and contribute to mental illness also. This is called a de novo genetic change,” says Dr. Vishwajit Nimgaonkar, a psychiatrist at the University of Pittsburgh Medical Center.

Perhaps the most telling argument for a split between nature vs. nurture is the fact that studies done on twins show that although they share the same genes, a diagnosis of a mental illness in one twin doesn’t necessarily mean a diagnosis for the other. In fact, that’s true in about 50% of the cases studied.

Some of the most common mental illnesses are:

  • Bipolar disorder
  • Anxiety disorders
  • Schizophrenia
  • Obsessive compulsive disorder
  • Post traumatic stress disorder
  • Eating disorders
  • Autism
  • Attention-deficit disorder
  • Alzheimer’s disease

It seems that, for now at least, there isn’t one definitive answer when it comes to whether or not nature or environment has the most say regarding mental health.