A recent study concludes that social interaction might be more than just a pleasant pastime; it might help doctors predict an individual's risk of cognitive decline and, perhaps, dementia.

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How does social interaction influence cognitive decline?

Cognitive decline refers to a general reduction in mental abilities over time.

It affects many people as they age and, in some cases, can lead to dementia.

As the average age of the population rises, an increasing number of people are likely to experience cognitive decline.

A group of researchers from Brigham and Women's Hospital in Boston, MA, are interested in the potential role that social interaction might play.

Specifically, their most recent study looked at whether there is an interaction between levels of social activity, cognitive performance, and the amount of beta-amyloid in the brain, which is a neurological hallmark of Alzheimer's disease.

Cognitive decline and sociability

To investigate, the scientists followed 217 older adults involved in the Harvard Aging Brain Study. At the beginning of the study, participants were aged 63–89 and showed no cognitive deficits. The authors followed the group for 3 years.

Each participant completed a questionnaire that ascertained their levels of social interaction; this included meeting family and friends, religious activities, and volunteer work.

The researchers also measured levels of beta-amyloid in each participant's brain. As expected, there was significant variability, with some people having much higher levels, putting them at increased risk of developing Alzheimer's.

The authors published their findings in The American Journal of Geriatric Psychiatry.

Although earlier studies have shown a relationship between social engagement and cognitive decline, scientists have not fleshed out the relationship between these two factors and levels of beta-amyloid in the brain.

A complex picture emerges

Overall, the authors found no relationship between social interaction and cognitive decline. However, when they delved into the beta-amyloid data, a pattern formed.

The researchers found that the influence of social activity was significant in individuals who had the highest levels of beta-amyloid in their brains. In this group, those with the lowest levels of social interaction showed higher levels of cognitive decline than individuals with similar levels of beta-amyloid but greater levels of social activity.

They also found that individuals who had lower cognitive abilities at the start of the study were more likely to become less socially engaged over the 3 years.

This effect remained significant even after the researchers accounted for a range of variables, including education, sex, level of social interaction at baseline, and age.

Interestingly, this relationship was not related to levels of beta-amyloid in the brain, which was counter to the authors' expectations.

These findings and those from earlier studies point to a relationship between social engagement and cognitive decline. However, it is still not clear whether individuals who socialize less are more at risk, or whether cognitive decline increases the likelihood of social withdrawal. Similarly, the relationship could run both ways and probably varies between individuals.

Conclusions and the future

The current study concludes that individuals with higher levels of beta-amyloid and reduced levels of social interaction might have an increased risk of more substantial cognitive decline.

The authors of the current study hope that their findings, one day, will help predict those who are most at risk of cognitive decline.

"Social engagement and cognitive function are related to one another and appear to decline together. This means that social engagement may be an important marker of resilience or vulnerability in older adults at risk of cognitive impairment."

Senior author Dr. Nancy Donovan

Although the findings are interesting, the study has a number of limitations. Firstly, the study only included data from 217 individuals, and the researchers followed them for just 3 years. Also, participants only completed questionnaires at the beginning and end of the study, so their answers may not represent levels of social interaction in the intervening years.

The authors also mention that current measures of social engagement need updating. For instance, they do not account for online interactions which, of course, can vary greatly and are not necessarily related to in-person social engagement.

Also, the current study could not control for certain potentially important factors, such as anxiety, depression, loneliness, and apathy. These factors can play a role in reducing the desire to interact socially; and according to earlier studies carried out by the same researchers, both loneliness and anxiety might have independent associations with Alzheimer's.

In the future, the authors would like to build on these findings. They plan to carry out work with a larger group and follow them for a greater length of time.

So, although research has still not solidified the relationship between social interaction, cognitive decline, the current work will help toward building a clearer picture.