How Is Mental Illness Passed through Families?

This article relates to Imagine Me Gone

In Imagine Me Gone, John and his son Michael, both struggle with mental illness.

Significant research has been conducted to search for the genetic basis for mental disorders. Family linkage and twin studies are particularly revealing. At present, there is no simple answer as to how mental illness might pass through families; environmental factors and the child's development interact with genetics to make it a very complex matter. Any mental disorder is probably encoded for by multiple genes, meaning it cannot be detected by a simple genetic test as is possible for conditions like Down's syndrome or cystic fibrosis.

However, according to the American Academy of Child and Adolescent Psychiatry, the susceptibility to mental illness "is particularly strong when a parent has one or more of the following: bipolar disorder, an anxiety disorder, ADHD, schizophrenia, alcoholism or other drug abuse, or depression." The National Institutes of Health add autism to that list.

A study published in The Lancet suggests that variations in two genes that affect the flow of calcium into neurons can affect the brain's circuitry, and might be associated with five major mental disorders: autism, ADHD, bipolar disorder, major depression, and schizophrenia. Mental illnesses also seem to be linked to variations in certain regions of chromosomes 3 and 10, with some especially noticeable connections seen between changes in chromosome 3 and bipolar disorder and schizophrenia. In addition, an unstable home environment, stress, drug use, abuse/neglect, and poor nutrition can increase a person's likelihood of manifesting a parent's mental illness. On the other hand, therapy, friendships, adult role models, and success in school and in hobbies can have a positive effect.

All in all, the inheritance pattern of mental illness is unpredictable – even the identical twin of a schizophrenic has only a 50% chance of developing schizophrenia, though this probability is 50 times higher than the risk in the general population. Patrick Tracey wrote a memoir, Stalking Irish Madness (2008), about his family history of schizophrenia, which affected his grandmother, his mother, and his two older sisters. He decided not to have children specifically so that he would not pass on what had come to seem like a family curse. Siddhartha Mukherjee, author of two popular science books, The Emperor of All Maladies (2010) and The Gene: An Intimate History, has also been open about his family's experience of "madness," including two uncles and a cousin who all had schizophrenia.

It's no wonder we're so fascinated by mental illness and its effect on families, whether in fiction or nonfiction. Mental health issues encourage many to find out how one person's future depends on links with past generations. The science is advancing all the time, but there are still more questions than answers – providing a rich field for a novelist's imagination.

(If your family is affected by any of the mental illnesses discussed here, you may find the resources at the National Society of Genetic Counselors to be helpful.)

Filed under Medicine, Science and Tech

This "beyond the book article" relates to Imagine Me Gone. It originally ran in June 2016 and has been updated for the February 2017 paperback edition. Go to magazine.

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