Psychiatric Disorders Have a Genetic Component. Now What?

"A recent large-scale study (Grotzinger et al, 2025) has found that psychiatric disorders have a genetic basis. Psychiatrists have always suspected as much, but no one has ever found a specific gene responsible for, say, anxiety. Instead, this new study shows that it takes a combination of several gene variants to lay the foundation for potential disorders. The study found that schizophrenia and bipolar disorder have similar genetic underpinnings."

"Only a handful of genes are truly decisive: Huntington's disease, for example, is an inescapable consequence of a mutation in a gene involved in brain function. But most of these newly discovered genetic variants are more subtle. The researchers found 238 variants involved in psychiatric disorders, none of which were definitive alone, but when combined, they contributed to various psychiatric effects."

"Outside of twins, we all have slightly varying genes that make us unique. The gene for eye color, for instance, includes blue, green, and brown variants. Some of the genetic variants are merely decorative, like eye, hair, or skin color, but others have more important functional differences, such as determining how our brain gets wired up. Environment also strongly contributes to psychiatric disorders by triggering inflammation."

Genetic analysis identified 238 variants that collectively influence risk for psychiatric disorders, with none acting as sole determinants. Schizophrenia and bipolar disorder share overlapping genetic factors forming a continuum, while depression, anxiety, and PTSD share a different overlapping genetic spectrum. Only a few genes cause deterministic diseases like Huntington's, but most psychiatric-related variants are subtle and interact combinatorially. Genetic variation affects brain wiring analogous to eye color variants. Environmental factors, particularly those inducing inflammation, strongly contribute to psychiatric conditions by interacting with genetic predispositions. The combined genetic and environmental influences complicate diagnoses and suggest spectrum-based conceptualizations.

Read at Psychology Today