It’s plenty tough to grow old when you live alone and have no satisfying contacts with either relatives or friends. Such isolation carries an added burden, however. It sharply boosts a person’s chances of developing Alzheimer’s disease or related brain ailments associated with advancing age, according to a 3-year investigation of elderly Swedes.
In contrast, marriage and a fulfilling social life appear to protect the elderly against these brain disorders, generally categorized as dementia, concludes a team headed by epidemiologist Laura Fratiglioni of the Stockholm Gerontology Research Centre.
What’s more, susceptibility to dementia rises steadily as social isolation intensifies, the researchers report in the April 15 Lancet.
“A poor social network may act as a precipitating factor for dementia, whereas an extensive social network can delay such an [outcome] by providing emotional and intellectual stimulation,” Fratiglioni says. The biological mechanisms by which social isolation promotes dementia are unknown, she adds.
Several earlier studies conducted by other investigators showed increased death rates among elderly people with few or no regular social contacts. The frequent development of dementia in this group may partly account for those findings, Fratiglioni now proposes.
The researchers studied 1,203 people, all at least 75 years old, living at home in Stockholm. Participants scored well on a standard test of mental functioning, and none exhibited medical signs of dementia.
Nurses interviewed each volunteer about his or her social life. A total of 84 individuals cited an extensive social network, which consisted of living with a spouse, maintaining regular, satisfying contacts with children, and having rewarding relationships with other relatives or friends. Another 880 people had a moderate social network that included any two of those three factors. A limited social network, consisting of a single factor, characterized 226 participants.
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Finally, the 13 people with poor social networks lived alone and weren’t in contact with relatives or close friends.
During the next 3 years, 176 cases of dementia—mainly Alzheimer’s disease but also some instances of dementia from damage caused by multiple strokes—developed in the Swedish sample.
The lowest incidence of dementia occurred among study participants with an extensive social network. Significantly higher rates of dementia emerged among volunteers with progressively more limited social networks.
The findings held for both men and women and for individuals who began the study with and without depression symptoms.
Marriage represented the strongest single protective factor against dementia, the scientists hold. Unless they also had other satisfying relationships, widowed or divorced participants living with an unmarried partner exhibited a higher risk of dementia than married people did.
Elderly individuals who had infrequent but satisfying contacts with children and friends still displayed a relatively low incidence of dementia. In contrast, participants citing frequent, unpleasant contacts with their children developed dementia even more often than did those who had no children.
The study didn’t account for participation in religious or secular organizations. The researchers also can’t say whether the people with poor or limited social networks had long led isolated lives or had abruptly lost many of their previous contacts at some time more than 3 years before the study began.
Still, the new data support the need for the elderly to interact with a variety of people in fulfilling ways, psychologist Lisa F. Berkman of the Harvard School of Public Health in Boston remarks in the same journal.
“Being alone is what is risky, not living alone,” she says. Scientists should examine whether certain living arrangements, such as group homes, protect against dementia in the elderly, Berkman adds.