You probably know that your genetic code controls physical attributes like your eye color. You might not know that you also have genes that are in charge of how you feel and behave, and that disruptions in those genes can lead to disease. Although there are thousands of connections between genes, emotions and illness (most are unexplored), this post focuses on the feeling of loneliness, which is known to be related to higher mortality rates, bad heart health, and cognitive decline. Experts claim there is a “loneliness epidemic” in America -- as of May 2018, nearly half of US adults identify as lonely.

Understanding why people feel lonely is the first step in combating this growing public health problem. Researchers at the University of Cambridge published a new study in Nature Communications showing that loneliness (and other related traits) could be influenced by parts of our genome. They analyzed over 450,000 pieces of genetic data from the UK BioBank alongside self-reported responses to three mental well-being questions related to perceived loneliness, frequency of social interactions, and ability to confide in someone. These measures were used to determine whether someone is struggling with mental or physical health problems that could be linked to loneliness.

The study showed that propensity for loneliness could be traced to 15 distinct gene regions that expressed a different type of DNA if the person felt socially isolated and/or lonely. Interestingly, the same genetic regions could also predict if people were more likely to be obese, neurotic or depressed -- connections that the researchers think could be causally related (but it’s not super clear how all those factors play into each other). This raises a nearly unanswerable question - can loneliness specifically be related to genes, or is it a result of an intermingling of other traits and genes? We know for sure that we can’t conclude there is a single “loneliness gene,” because complex social traits involve both genetic and non-genetic factors.

However this isn’t the first time scientists have studied loneliness as a genetic risk factor for illness. A 2017 paper in The Lancet analyzed the same UK BioBank dataset and also found that obesity and a lower mental well-being could contribute to mortality among lonely people. In 2010 AARP conducted a huge "Loneliness Study" of older adults that identified loneliness as a predictor for poor health, and in 2011 research published in Science showed that chronically lonely people’s genes can cause high levels of inflammation, which leads to heart disease, increased susceptibility to viruses, and a host of other issues.

Overall, these genetic clues could explain why some of us feel lonelier than others, and more research on the topic might allow us to be able predict when people are at risk for loneliness. Such predictions could potentially lead to lower rates of loneliness-related disease by enabling doctors to identify and treat related mental health (depression) / physical health (obesity) issues more effectively.

Here’s what you might want to do as a result of this information. If you feel lonely, know that it's partially genetic, but there’s a lot you can do to take control: exercise, spending meaningful time with friends and family, and getting more sleep can all help combat the feelings of loneliness.

Note from Lauren: This is the first in a “Research Review” series, where I’ll be reviewing new research that comes out, summarizing it, and providing more context.