Loneliness raises dementia risk by 31%, new study finds

Loneliness in midlife and old age increases the risk of dementia by 31 per cent, according to a major new analysis of nearly 609,000 people worldwide.

There’s no cure for dementia, which affects about 7.9 million people across the European Union. But the risks include a combination of genetic and lifestyle factors, like physical activity, smoking, drinking alcohol – and even the quality of our social connections.

The new study, published in the journal Nature Mental Health, found that loneliness raises the risk of all-cause dementia, Alzheimer’s disease, and vascular dementia, which is a greater risk for older adults with diabetes or obesity.

It also increases the risk of cognitive impairment – a more general problem that covers memory loss and trouble making decisions, concentrating, or finishing activities – by 15 per cent.

The findings held up even when researchers took depression, social isolation, and other potential risk factors into account.

They indicate that “loneliness is a critically important risk factor in the future development of dementia,” Páraic Ó Súilleabháin, one of the study’s authors and psychology lecturer at the University of Limerick in Ireland, said in a statement.

Loneliness is a layered issue

Researchers in Ireland, Switzerland, France, the United States, and China, combined data from 21 ageing studies around the world, in what they say is the biggest meta-analysis to date on the link between loneliness, dementia, and cognitive decline.

Most of the studies asked people whether they felt lonely at least sometimes, while a few also assessed how intense their loneliness was.

Across the EU, 35 per cent of people say they are lonely at least some of the time, with the highest rates in Ireland, Luxemburg, Bulgaria, and Greece.

“There are different types and sources of loneliness that can affect cognitive symptoms across the dementia continuum,” Martina Luchetti, the study’s lead author and an assistant professor at Florida State University in the US, said in a statement.

Ó Súilleabháin said the results help shed light on why loneliness appears to be linked to longevity, or how long people live. 

Prior studies have found a tie between loneliness and health issues like stroke and Parkinson’s disease.

The study authors said that going forward, it will be important to investigate why people feel lonely, and the type of loneliness they’re experiencing, in order to intervene and curb the risk of cognitive decline and dementia later on.

“Addressing loneliness promoting a feeling of connectedness could be protective for cognitive health in later life,” Luchetti said.