A new study finds that lonely people are more than 30% more likely to develop dementia than those who don’t experience loneliness. Florida State University College of Medicine researchers analyzed data from more than 600,000 men and women worldwide, combining results from 21 long-term studies to paint a comprehensive picture of how social isolation affects our cognitive health.

“These results are not surprising, given the mounting evidence that links loneliness to poor health,” said assistant professor Martina Luchetti, who led the study, in a university release. Luchetti, who works in the Department of Behavioral Sciences and Social Medicine, emphasized that studying the effects of loneliness is important to all aspects of cognitive function. The new analysis, published in Nature Mental Health, found that loneliness is a major risk factor for cognitive impairment, regardless of age or sex. It’s also associated with more specific causes of dementia, such as Alzheimer’s disease.

A previous study by the Mayo Clinic revealed that social isolation is also linked to a biological age gap and higher mortality rate. Researchers found that socially isolated people are more likely to show signs of being biologically older than their age and more likely to die from a variety of causes.

The World Health Organization and Dr. Vivek H. Murthy, the Surgeon General of the United States, say that loneliness is a cause for public health concern and that it is a root cause of many of the epidemics sweeping the world today, ranging from alcohol and drug addiction to violence, depression, and anxiety. In his book, Together: The Healing Power of Human Connection in a Sometimes Lonely World, Murthy writes that loneliness not only affects our health but also how our children experience school, how we perform in the workplace, and the sense of division and polarization of our society.

“There has been a lot of interest in the consequences of loneliness for health,” said Luchetti. “It is important to understand why and under what circumstances it increases risk for late life dementia.” The meta-analysis results may help provide information for future prevention and intervention efforts to curb the epidemic of loneliness, that was evident even before the pandemic.