Older people with impaired thinking or “cognitive” function are at greater risk of dying within a few years than those with intact cognitive function, new research from the UK confirms.

And while older people who were more socially engaged have a lower risk of dying, social connectedness doesn’t appear to influence the risk of death in people with cognitive impairment, Dr. Elizabeth L. Sampson of the London School of Hygiene and Tropical Medicine and colleagues report.

One in five people aged 65 and older is cognitively impaired, Sampson and her team point out in the latest issue of the Journal of the American Geriatrics Society. While cognitive impairment is known to reduce a person’s likelihood of survival, they add, several factors may be involved in the relationship, such as smoking, poor health, and depression.

To better understand the relationship, along with the role of social support, the researchers looked at 10,720 elderly men and women. At the study’s outset, 13% had mild cognitive impairment, while 2% had moderate to severe cognitive impairment.

During follow-up lasting 6 to 10 years, the people with mild cognitive impairment were at 31% greater risk of dying than people with no cognitive trouble. The risk of dying was 64% greater for people with moderate to severe impairment.

The researchers also determined levels of social engagement among study subjects and found that people with a medium amount of social engagement were 18% more likely to die during follow up than those who were highly socially engaged, and the risk was 29% greater for those with low levels of social engagement.

But there was no relationship between social engagement and death for people with impaired cognitive function.

“These results suggest that, although social engagement and interventions to enhance it may improve the quality of life in older people with dementia, they may not affect mortality risk,” Sampson and her colleagues say.

Nevertheless, they add, social engagement had “modest but significant” effects on survival for the population as a whole, and efforts to help older people become more socially connected could benefit public health.

SOURCE: Journal of the American Geriatrics Society, June 2009.