Reviewed by John M. Grohol, Psy.D. on December 11, 2012
Noting the aging population and the increased number of people living alone, researchers decided to track the long-term health and well-being of more than 2,000 people with no signs of dementia and living independently for three years.
All the participants were taking part in the Amsterdam Study of the Elderly (AMSTEL), which is looking at risk factors for depression, dementia, and higher than expected death rates among the elderly.
At the end of the three years, the participants’ mental health and well-being was assessed using a series of tests. They also were quizzed about their physical health, their ability to carry out routine daily tasks, and specifically asked if they felt lonely. Finally, they were formally tested for signs of dementia.
At the start of the monitoring period, around half — 46 percent or 1,002 people — were living alone and half were single or no longer married, according to the researchers. Around three out of four said they had no social support. Around one in five — just under 20 percent or 433 people — said they felt lonely.
Among those who lived alone, around one in 10 — 9.3 percent — had developed dementia after three years compared with one in 20 — 5.6 percent — of those who lived with others. Among those who had never married or were no longer married, similar numbers developed dementia, the researchers noted.
When it came to those who said they felt lonely, more than twice as many developed dementia after three years compared with those who did not feel this way (13.4 percent compared with 5.7 percent).
Further analysis showed that those who lived alone or who were no longer married were between 70 percent and 80 percent more likely to develop dementia than those who lived with others or who were married, the researchers reported.
And those who said they felt lonely were more than 2.5 times as likely to develop the disease. This applied equally to both sexes, according to the study.
When other factors were taken into account, those who said they were lonely were still 64 percent more likely to develop dementia, while other aspects of social isolation had no impact, the researchers said.
“These results suggest that feelings of loneliness independently contribute to the risk of dementia in later life,” the researchers say in the study, which was published online in the Journal of Neurology Neurosurgery and Psychiatry. “Interestingly, the fact that ‘feeling lonely’ rather than ‘being alone’ was associated with dementia onset suggests that it is not the objective situation, but, rather, the perceived absence of social attachments that increases the risk of cognitive decline.”
The researchers suggest that loneliness may affect cognition and memory as a result of loss of regular use, or that loneliness could itself be a sign of emerging dementia, and either be a behavioral reaction to impaired cognition or a marker of undetected cellular changes in the brain.
Source: Journal of Neurology Neurosurgery and Psychiatry