How Loneliness Makes You Sick

One is the loneliest number, and it may be the sickest number, as well. A new study from a team of researchers, including UChicago psychologist and leading loneliness expert John Cacioppo, sheds light on why being lonely is such a major health risk.

Previous research from Cacioppo and UChicago showed that feeling lonely can up an older person’s chances of premature death by 14 percent. But the biological reasons why haven’t been well understood. This study looked at adults aged 50 to 68, as well as a species of monkey called rhesus macaques, which are known for being particularly sociable. Researchers looked at gene expression in leukocytes, cells in the immune system that help protect our bodies against bacteria and viruses. In both lonely humans and lonely macaques, there was decreased expression of genes involved in antiviral response. Interestingly, this gene expression and loneliness seem reciprocal: the gene expression could predict loneliness measured a year or so later.

Loneliness also triggered higher levels of the “fight or flight” neurotransmitter, norepinephrine. This stimulates blood stem cells in bone marrow, up-regulating the body’s inflammation response. So loneliness was causing more inflammation and less viral protection, causing less optimal health conditions.

According to Cacioppo’s 2014 work on the health risks of loneliness, symptoms can include interrupted sleep, depression, higher levels of the stress hormone cortisol, and increased blood pressure. He says it isn’t actual isolation that causes health risks—some people are completely fine with solitude—but a profound sensation of being alone that causes negative effects. His research suggests three important areas where we can foster healthy relationships as we age:

1. Intimate connectedness, which comes from have people in your life who affirm who you are.
2. Relational connectedness, which means having face-to-face interactions that feel mutually rewarding.
3. Collective connectedness, or a feeling that you are part of something that is bigger than yourself, something beyond your individual existence.

These three types of connectedness help older adults become more resilient, less depressed and have higher subjective well-being.

“Retiring to Florida to live in a warmer climate among strangers isn’t necessarily a good idea if it means you are disconnected from the people who mean the most to you,” wrote Cacioppo in his study. Population changes make understanding the role of loneliness and health all the more important, he explained.