Evolution of immune mechanisms can shape genetic risk of mental illness

How changes to our genome caused by natural selection increase the risk of mental illnesses is a deep biological issue

Evolution is a process of natural selection in which traits that improve the fitness of the organism to survive the challenges posed by its surrounding environment. However, genes have multiple effects: The very same genes that are responsible for improving an aspect of the fitness of the organism may have other contributions too, such as increasing the risk for a non-communicable disease. A paper published recently in Scientific Reports shows that this may be the case also with some severe mental illnesses, like schizophrenia and bipolar disorder.

The study examined 80 individuals from 80 separate families from southern India, which each had several members affected by severe mental illness. Each of these 80 individuals had at least two first-degree relatives who had a major psychiatric disorder, such as schizophrenia, bipolar disorder, obsessive compulsive disorder, dementia or substance use disorder.