Happiness is a positive emotional state that influences various clinical outcomes, including depression.

Previous studies have shown that humans have a baseline happiness level, which remains relatively stable. In fact, this baseline level of happiness likely remains constant, even after vital positive or negative life events such as winning the lottery or experiencing a serious car accident.

A recentScientific Reports study developed a novel LDpred-inf polygenic score that measures happiness in general. This approach has been used to determine whether the well-being of an individual depends on happiness measures.

Study: Consistent effects of the genetics of happiness across the lifespan and ancestries in multiple cohorts. Image Credit: Ground Picture / Shutterstock.com

About the study

The United Kingdom Biobank study is the most extensive genome-wide association study (GWAS) conducted to date, comprising over 222,000 individuals. The U.K. Biobank asked study participants, “In general, how happy are you?” twice, once at the beginning of the study and again five years later.

At both time points, GWAS was performed,d and their results were combined to obtain happiness polygenic scores (PGS). In addition to the U.K. Biobank participants, two additional cohorts, including the Adolescent Brain Cognitive Development (ABCD) cohort and National Longitudinal Study of Adolescent to Adult Health (Add Health,) were also included in the analysis. 

Each cohort comprised specific age groups. To this end, the ABCD cohort included children between nine and 11 years of age, the Add Health cohort comprised individuals between 25 and 35 years of age, and the U.K. Biobank comprised individuals between 40 and 70 years of age.

The current study assessed whether the genetic predisposition of the general happiness level is related to differences in white matter integrity or major brain structures. The researchers also investigated whether happiness measures influenced well-being across all age groups.

Saliva samples of the participants were collected and genotyped. Additionally, magnetic resonance imaging (MRI) of the participants’ brain were performed.

LDpred-inf polygenic scores of a general happiness measure were constructed based on the ABCD and Add Health cohorts. The association between genetic scores for happiness and brain structure was determined using ABCD and U.K. Biobank data.

Study findings

The LDpred PGS analyses using Add Health and ABCD cohorts revealed that, genetically, happiness is mostly a consistent effect throughout an individual’s lifespan from 12 to 73 years of age. This effect was consistent across multiple ancestral backgrounds, except those of non-white ancestries in the Add Health cohort.

The genetic predisposition of happiness influences the well-being of an individual. The well-being is linked with being confident, calm, concentrated, and energetic. This genetic loading also influences brain structure that is related to psychological and cognitive health.

The MRI analyses indicated that only some regions of the brain are associated with genetic predispositions for happiness; however, this prevalence could be underestimated due to known biases present within the MRI subsample.

In the ABCD cohort, several brain regions linked with genetic loading for happiness were identified. These regions are present in hedonic brain circuitry that includes nucleus accumbens and ventral pallidum. Furthermore, these regions are strongly associated with the regulation of pleasure and happiness.

Previous studies have indicated that the putamen, caudate nucleus, and core of the accumbens nucleus are linked with experiencing pleasure. The accumbens nucleus and bed nucleus of the stria terminalis also appear to contribute to experiencing happiness.

In the ABCD cohort, an association between the white subsample and volumes of the left ventral pallidum was observed. A similar association with the nucleus accumbens was not observed in the ABCD cohort; however, a marginal association was identified in the U.K. Biobank analysis.

Previously, the frontal lobe of the brain has been associated with hedonic emotions. Likewise, the researchers of the current study confirmed that significant frontal lobe volume was associated with hedonic emotions. 

Conclusions

The genetic basis for general happiness level appears to have a consistent effect on happiness and wellbeing measures throughout the lifespan, across multiple ancestral backgrounds, and multiple brain structures."

The current study demonstrates the genetic basis of happiness levels, which is consistent across age groups and ancestral backgrounds. Furthermore, a significant association between happiness and well-being measures was observed throughout the life span of an individual.