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Social isolation may affect brain health more than thought. Adam Lister/Getty Images
  • A new analysis of data from a large, nationally representative group of older Americans finds an association between being socially isolated and developing dementia.
  • People at risk are those who only infrequently have contact with others and have few active relationships.
  • The study’s finding suggests that by remaining or becoming more socially active, one may reduce the risk of dementia.

A new study has investigated whether social isolation can have an effect on the development of dementia in older people.

The new analysis indicated that socially isolated adults were 28% more likely to develop dementia over a period of nine years, regardless of race or ethnicity, compared to people who weren’t socially isolated.

The study is an analysis of data from 5,022 older U.S. adults who took part in the longitudinal National Health and Aging Trends Study (NHATS). Of the NHATS study cohort, 1,172 individuals, or 23.3%, were classified as socially isolated — 3,850 (76.7%) were not.

Beyond its association with dementia, social isolation has also been linked to poor mental health and emotional well-being in older people.

The study is published in the Journal of the American Geriatrics Society.

While there is no universal understanding of what “social isolation” means, the study bases its use of the term on the definition presented in a report from the National Academies of Sciences, Engineering, and Medicine, which says:

“Social isolation is defined as the objective state of having few social relationships or infrequent social contact with others.”

The new study lists several attributes that qualify a person as being socially isolated: living alone, having no one or only one person with whom they can discuss important matters, and having little or no engagement in social or religious groups.

The people who qualified as socially isolated in the study met two or more of the following conditions:

  • Lived alone.
  • They did not have two or more people in the last year with whom they could discuss important issues.
  • They did not attend religious services in the past month.
  • Did not do participate in other activities, such as volunteer work, clubs, meetings, or groups, in the last month.

The authors of the study mention to Medical News Today the importance that future research investigates social isolation and dementia in a more detailed manner. Such research may look into the effect each individual criterion may have on dementia.

They also envision future studies that consider possible differences in the way social isolation may arise and influence different race and ethnicity groups.

Dr. Rosanne Freak-Poli, senior research fellow at Monash University’s Medicine Monash Health, who was not involved in the study, pointed out that “[s]ome people may confuse social isolation with social support.”

Social support, she said, is about how social contacts are utilized. For example, a person may feel sufficient support from a few good friends who fulfill their social needs.

“I like to describe people as ‘enjoying their solitude’ if they are socially isolated but also feel socially supported,” she told MNT.

NHATS surveyed people residing in communities and did not include older people institutionalized in nursing homes or residential care.

“However, people in nursing homes or residential care often report feeling lonely or having low social support. Loneliness and low social support are also risk factors for ill health and lower well-being,” said Dr. Freak-Poli.

Meanwhile, Dr. Angelina R. Sutin, professor at Florida State University’s College of Medicine, who was not involved in the current study, said she was “not aware of any studies that have examined whether social health in residential settings is associated with dementia risk.”

She noted that most existing research focuses on people in such settings who already have dementia.

The study’s corresponding author, Dr. Thomas K. M. Cudjoe, assistant professor of medicine at Johns Hopkins Medicine in Baltimore, Maryland, described three ways in which social isolation may lead to dementia.

First, he cited a strong association between social isolation and physical and mental health risk factors for dementia, such as hypertension, coronary heart disease, and depression. As social isolation promotes these conditions, it may increase the risk of dementia.

Dr. Cudjoe also noted that a lack of social engagement could lead to a reduction in cognitive activity and, therefore a lower cognitive reserve.

“The cognitive reserve hypothesis suggests individuals with lower levels of cognitive functioning and reserve are more susceptible to the pathology associated with dementia.”
— Dr. Thomas K. M. Cudjoe

Finally, Dr. Cudjoe proposed that socially isolated individuals may lack benefits associated with greater social connectedness, including social support, information-sharing, coordination of healthcare services, and access to those services.

“Social isolation matters for cognitive health. Clinicians should be thinking about and assessing the presence or absence of social connections in their patients,” said Dr. Cudjoe.

Dr. Cudjoe said the study’s nationally representative group of participants strengthens its conclusions, allowing them to be generalized across U.S. populations.

“This is important in our thinking of broad-based solutions or policy,” he said.

Older adults may consider reaching out more to other people, either on an individual basis or by participating in activities with groups of people, to lower the risk of developing dementia.

“Getting out of your home and interacting with people at least once per month can have huge benefits to your future health and immediate well-being.”
— Dr. Rosanne Freak-Poli

“When I think about the other health behaviors, such as healthy eating or physical activity, they seem more difficult to achieve for the same health benefit,” added Dr. Freak-Poli.

Dr. Sutin underscored the study’s upside:

“The good news is that social isolation is modifiable, and could be a target of intervention that may help reduce the risk of dementia associated with it.”