Scientists have discovered genetic variables that cause symptoms of anxiety, autism, and attention-deficit/hyperactivity disorder (ADHD).

The multinational study, which was headed by King’s College London in the United Kingdom, looked at how different people’s sensitivity to environmental influences can affect their levels of neuroticism, anxiety and depression symptoms, ADHD symptoms, autistic features, and psychotic episodes.

To find genetic variations associated with environmental sensitivity, researchers from 23 universities worldwide aggregated data from 11 studies, including up to 21,792 identical twins (10,896 pairs). This is the biggest identical twin genome-wide association study (GWAS) to date.

They discovered a number of genetic variables associated with variations in environmental sensitivity among identical twin pairs. The researchers in the study, which was published in the journal Nature Human Behaviour, suggested that variations in vulnerability to psychiatric and neurodevelopmental disorders could be explained by the interplay between these genetic variables and environmental exposures.

“Depending on a person’s genetic composition, the same positive or negative experiences may have different consequences on their mental health due to differences in sensitivity to life experiences. Our results imply that certain genetic variations affect the way environmental exposures affect neurodevelopmental and psychiatric symptoms,” stated Dr. Elham Assary, a postdoctoral researcher at King’s.

The researchers discovered that genes connected with growth factors, which are biological components that are crucial for immunological response, neurodevelopment, and the central nervous system, were linked to differences in autistic features among the genetically identical twins.

Variations in depression symptoms were associated with genes connected to stress reactivity. According to the team, differences in psychotic-like episodes were associated with genes that control catecholamines, a class of hormones that are released in reaction to stress.

These results support the idea that genes impact psychiatric and neurodevelopmental characteristics in part by influencing how individuals react to their environment. According to Professor Thalia Eley, a professor of developmental behavioral genetics at King’s, “some people are more sensitive to their circumstances, which can be positive in good circumstances but can make life more challenging than for others in stressful circumstances.”