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Loneliness is more than a feeling of isolation. It has been linked to poor physical and psychological health. Actually, it has been shown to be a more accurate predictor of early death, greater than obesity.

Researchers at University of California San Diego School of Medicine just released the results of the first genome-wide association study on loneliness as a lifetime trait, not a temporary occurrence. The study was led by Abraham Palmer, PhD, professor of psychiatry and vice chair for basic research at the university.

Palmer says,

For two people with the same number of close friends and family, one might see their social structure as adequate while the other doesn’t. And that’s what we mean by “genetic predisposition to loneliness” – we want to know why, genetically speaking, one person is more likely than another to feel lonely, even in the same situation.

Palmer and his team used information collected by the Health and Retirement Study, a longitudal study sponsored by the National Institute on Aging at the National Institutes of Health. They examined genetic and health data from 10,760 people aged 50 years and older. The study accounted for gender, age and marital status.

As part of the study, participants answered three established questions that measured loneliness. The first question was, how often do you feel that you lack companionship? The second, how often do you feel left out? The last, how often do you feel isolated from others?

Loneliness may be measured over a lifetime.

Loneliness may be measured over a lifetime.

The team found that people tend to feel lonely over a lifetime. Loneliness also appears to be co-inherited, with 14 to 27 percent genetic. This is interesting because previous studies, that looked at young adults in Europe, estimated that 37 to 55 percent of loneliness was determined by genetics.

The researchers also found that loneliness tends to be co-inherited with neuroticism, a long-term emotional state linked to depressive symptoms.

Palmer and team writes,

We identified strong genetic correlations between loneliness, neuroticism and a scale of “depressive symptoms.” We also identified weaker evidence for co-hertitability with extraversion, schitzophrenia, bipolar disorder and major depressive disorder. We conclude that loneliness as defined in this study, is a modestly heritable trait that has a highly polygenic genetic architecture. The co-heritability between loneliness and neuroticism may reflect the role of negative affectivity, which is common to both traits. Our results also reflect the value of studies that probe the common genetic basis of salutary social bonds and clinically defined psychiatric disorders.

Palmer and his team are now trying to find a genetic predictor, a specific genetic variation, that would allow additional insights into the molecular mechanisms that influence loneliness.