Emerging Theory: 'Loneliness Is a Symptom of Dementia'

Loneliness isn't just associated with a higher risk of death, but also a higher risk of dementia, new research suggests. A meta-analysis of 21 studies involving more than 600,000 people finds loneliness is associated with an increased risk of cognitive impairment and dementia from any cause. Participants were asked to rate how often they feel lonely and that they lack companionship, while their cognition was evaluated using tests or a dementia diagnosis, reports the Washington Post. After controlling for depressive symptoms and dementia risk factors, researchers found feeling lonely increases one's risk of cognitive impairment by 15% and one's risk of all-cause dementia by 31%. This suggests loneliness is as bad as sedentary behavior or smoking when it comes to dementia risk.

Other studies have linked loneliness—a chronic state for as much as 15% to 30% of the population—with dementia risk, poorer executive function, lower total brain volume, and greater damage to the brain's white matter, the Post reports. It could be that "feeling lonely leads to reduced social participation, meaning less opportunity for cognitive stimulation and greater vulnerability to cognitive decline" or that "loneliness is a symptom of dementia that appears decades before an actual diagnosis," the outlet notes.

The results of the study published last month in Nature Mental Health certainly suggest "loneliness is a critically important risk factor in the future development of dementia," says co-author Páraic Ó Súilleabháin, an associate professor of psychology at the University of Limerick, per Euronews. "Loneliness is relevant to cognition in general, across the dementia spectrum" and "is associated with multiple cognitive outcomes besides the endpoint of dementia," notes lead author Martina Luchetti of Florida State University's College of Medicine. While there's no cure for dementia, "promoting a feeling of connectedness could be protective for cognitive health in later life," she adds. (More loneliness stories.)