You might be aware that many medical conditions such as coronary heart disease, diabetes and hypertension are hereditary. Similarly, if someone in your family has a mental illness, you may wonder if you will inherit it. If you or your spouse is getting treated for a mental illness, you may be worried about your children inheriting the illness.
Although mental illness can run in families, research evidence indicates that most people with mental illnesses do not have relatives with a mental illness.
“Genetic studies show that it is not just a single gene that puts someone at the risk of a mental illness. It is a combination of genes on different chromosomes that increase the tendency to inherit a mental illness. One can draw parallels to the risk of inheriting diabetes, hypertension or cardiovascular disease,” says Dr Deepak Jayarajan, assistant professor, department of psychiatry, NIMHANS.
So, what are the chances of inheriting a mental illness?
Lifetime chance (the chance of someone in the general population developing the condition during their lifetime)
10-25 % females
5-12 % males
15-25 % for any anxiety disorder
If one of your biological parents has the condition
Varies from the type of anxiety disorder. For eg, 20% in the case of generalized anxiety disorder and 8-31% in the case of panic disorder
If both of your biological parents have the condition
35 - 46 %
50 – 65 %
If a sibling (brother or sister) has the condition
If a non-identical twin has the condition
10 – 16 %
If an identical twin has the condition
If a second degree relative (aunt or uncle) has the condition
These are worldwide numbers, and the risk of inheriting a mental illness signified is representative for the overall population. The statistics suggest that the risk of having a mental illness is higher if a first degree relative (parents or siblings) has been diagnosed with a mental illness.
Are only genes responsible for mental illness?
No. Research points out that genes alone don’t typically cause mental illness and that there are other factors at play. Mental illnesses occur due to the interaction of genetic and environmental factors such as stress, abuse, childhood trauma, poverty and malnutrition. This means that even if an individual is carrying ‘risk genes’ (genes associated with a mental illness); the environmental and social factors can alter the way in which the inherited genes are expressed.Therefore, there are other factors involved that can trigger or precipitate a mental illness. Also, the chance of inheriting an illness reduces with age; as the onset age for most mental illnesses is 18-25 years.
How will knowing the risk of inheriting the genes and other risk factors associated with mental illness help me?
Now, you may wonder - how do the numbers indicated in the table translate to my situation? Knowing that you have a certain amount of risk for a mental illness due to inherited genetic vulnerabilities, and that other factors can alter gene expression, there are ways of reducing the risk. Just as in the case of diabetes and hypertension, the risk of inheriting a mental illness remains but can be reduced and altered by:
Family members and caregivers who have any doubts or concerns about themselves or their children inheriting a mental illness can discuss with a psychiatrist and/or a genetic counsellor.