Older adults who experience loneliness may face a faster decline in both mental and physical health, according to research published on June 16. The study, led by the University of California, Davis, analyzed data from 18 countries and found that loneliness plays a stronger role in cognitive impairment and shorter life spans than social isolation alone.
Researchers used advanced statistical modeling to examine how loneliness and social isolation affect transitions between various stages of cognitive impairment up to mortality. The study included responses from 175,000 participants over the age of 50 who reported how often they felt lonely as well as their frequency of contact with others.
"This approach is crucial," said Yoneda, "because cognitive impairment increases mortality risk, and both risks increase with age." The analysis showed that even after accounting for social isolation, loneliness was consistently associated with a higher risk of cognitive impairment and reduced lifespan. Social isolation by itself was not consistently linked to cognitive decline and had only a weak association with shorter life expectancy.
A key finding indicated that a 10% increase in reports of feeling lonely correlated with an 8%-9% increased risk of severely impaired cognitive function or moving from no impairment to mild impairment. Reporting loneliness more frequently also meant participants were 3% less likely to recover from mild cognitive impairment. Researchers suggested this highlights the importance of addressing loneliness for potential recovery. They also found that higher levels of loneliness posed the most consistent risk earlier in life before measurable signs of cognitive decline appeared.
"Loneliness may be most prominent in early stages of cognitive impairment, but is also a risk factor after impairment develops," said Eileen K. Graham, associate professor at Northwestern University and supervising author on the study. "Lonelier individuals may be more likely to progress to more severe stages and less likely to recover."
The researchers recommended efforts aimed at reducing loneliness among older adults as one way to blunt its effects on cognition—and potentially reduce costs related to dementia care. Suggestions included using screening tools for loneliness in hospitals or care organizations, as well as creating community opportunities for engagement among older adults.
