Eleven genetic variants across 298,000 people were found in a novel genome-wide association study (GWAS) that marks the first genes clearly identified as those governing subjective well-being, depression, and neuroticism.
"This study is both a milestone and a new beginning: A milestone because we are now certain that there is a genetic aspect to happiness and a new beginning because the three variants that we know are involved account for only a small fraction of the differences between human beings,” said VU Amsterdam’s Meike Bartels, PhD. “We expect that many variants will play a part."
A collaborative, international project directed by the VRIJE Universiteit Amsterdam
and published in Nature Genetics
examined entire genomes looking for genes associated with three phenotypes: subjective well-being, depressive symptoms, and neuroticism. Questions about life satisfaction and happiness determined the subjective well-being phenotype, while reports of anxiety, low energy, bodily aches and pains, and pessimism characterized depression.
defines neuroticism as having “emotional instability,” a personality trait that is also associated with depression. Of the three phenotypes examined in this study, three gene variants were found to be associated with subjective well-being, two with depressive symptoms, and 11 with neuroticism, plus two inversion polymorphisms. Other than previous twin studies genetically linking depression to subjective well-being, little has been scientifically proven to connect these three phenotypes together genetically.
Thanks to the 16 genome-wide significant associations between the three phenotypes, the scientists involved in this study prove a high genetic correlation among the three conditions for the first time.
They started with looking for single nucleotide polymorphisms (SNPs) associated with subjective well-being that “quasi-replicated.” They tested the SNPs for association with depression and neuroticism, as well as the SNPs for depression and neuroticism with the subjective well-being SNPs. The findings were positive; associations were there.
The also used a method called the “Proxy-Phenotype” approach, where they continued to compare gene loci associated with subjective well-being for association with depressive symptoms and neuroticism. The genetic variants for happiness they found are mainly expressed in the central nervous system, adrenal glands and pancreatic system.
This study is largely reliable due to the sample size. Their ability to show genetic overlap between the three phenotypes provides solid evidence for genetic connections between the three conditions, and they are hopeful for the future to learn even more about how these genes cause disease.
Source: VRIJE Universiteit Amsterdam