“We have known for a long time that these traits have a genetic component, but until now, we had identified only a few specific genetic variants related to these traits,” said Dr. Daniel Benjamin, corresponding author and an associate professor of the Center for Economic and Social Research at University of Southern California (USC).
Benjamin said that the genetic variants do not determine whether someone develops depressive symptoms, neuroticism, or have a poor sense of wellbeing.
“Psychological well-being is jointly influenced by genes and environment,” he said. “The genetic variants that we found account for a small fraction of these genetic associations.”
In the study, more than 190 scientists analyzed the genomes of 298,420 individuals. Their findings appear in the journal Nature Genetics.
Three genetic variants were identified as being associated with “subjective well-being,” or how happy or satisfied a person reports feeling about his or her life. The genetic links were found upon analysis of roughly 300,000 people.
Additionally, two genetic variants associated with depressive symptoms, discovered based on an analysis of nearly 180,000 people. Eleven genetic variants were found to be associated with neuroticism, based on an analysis of 170,000 people. The depression results were replicated through an analysis of another sample of nearly 370,000 people.
“We found that most of the genetic variants associated with depressive symptoms and/or neuroticism also were linked to subjective well-being, and vice-versa,” Benjamin said.
Benjamin is quick to point out that the genetic links are only a part of the behavioral outcomes.
“When examined individually, each genetic variant explains very little about these traits. But when taken together, these findings imply that the genetic influences on depression, neuroticism, and subjective wellbeing result from the cumulative effects of at least thousands, if not millions, of different variants.”
The study also found that subjective well-being, neuroticism, and depression are predominantly influenced by the same set of genes. The scientists said this finding indicates that researchers may want to consider studying these traits jointly for future work.
The interdisciplinary team included medical researchers and psychologists and also studied whether the genetic variants that they had identified were associated with other significant mental disorders. Researchers looked for genetic variants associated Alzheimer’s disease, anxiety disorders, autism spectrum disorder, bipolar disorder, and schizophrenia.
The strongest link was with anxiety disorders. The researchers also found the genetic variants tied to subjective well-being, depression and neuroticism moderately overlap with the variants that are associated with schizophrenia and bipolar disorder.
Because the study has found some of the first genetic variants associated with well-being, depression and neuroticism, it is too soon to draw conclusions about how the genes affect biological mechanisms, Benjamin said.
Despite the wealth of knowledge gained from the genetic links, the scientists issued several cautions for interpreting the results of their study.
“Genetics is only one factor that influences these psychological traits. The environment is at least as important and it interacts with the genetic effects,” Benjamin said.