The meta-analysis of 21 longitudinal studies showed that experiencing feelings of loneliness increased the risk of developing dementia by 31%. The research was published in Nature Mental Health.

“These results are not surprising, given the mounting evidence that link loneliness to poor health,” said Assistant Professor Martina Luchetti, who led the study. “Dementia is spectrum, with neuropathological changes that start decades before clinical onset. It is important to continue studying the link of loneliness with different cognitive outcomes or symptoms across this spectrum. Loneliness — the dissatisfaction with social relationships — may impact how you are functioning cognitively, and in daily life.”

The analysis revealed that loneliness is a major risk factor for cognitive impairment, independent of age or sex. It also linked loneliness to specific causes of dementia, such as Alzheimer’s disease, and cognitive impairments that can occur before a diagnosis.

The team’s work was spurred by the World Health Organization and U.S. Surgeon General, who declared loneliness a public health crisis in the wake of the COVID-19 pandemic and its associated social restrictions.

“There has been a lot of interest in the consequences of loneliness for health,” Luchetti said. “It is important to understand why and under what circumstances it increases risk for late life dementia.”

Although data for the study included subjects from around the world, most of it was collected from people in wealthier Western Hemisphere cultures. Future research should incorporate more data from other countries, Luchetti said.

“We know there are rising cases of dementia in low-income countries,” she said. “Future studies need to gather more data from those countries to evaluate what are the effects of loneliness in different national and cultural contexts.”

The meta-analysis results provide information that can guide future prevention and intervention efforts.

“Now that there is solid evidence of an association, it is critical to identify the sources of loneliness to both prevent or manage loneliness and support the well-being and cognitive health of aging adults,” Luchetti said.

The research was supported by a grant from the National Institute on Aging, part of the National Institutes of Health.

Luchetti is an assistant professor in the Department of Behavioral Sciences and Social Medicine. Her co-authors at FSU were Damaris Aschwanden, a post-doctoral researcher; Amanda Sesker, a post-doctoral scholar; Professor Antonio Terracciano of the Department of Geriatrics and Professor Angelina Sutin of the Department of Behavioral Science and Social Medicine, all from the FSU College of Medicine. Researchers from Wenzhou Medical University, University of Limerick and University of Montpelier were also co-authors.