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Study Reaffirms That Friends Keep Dementia Away

New research over a 28-year follow-up period finds significant evidence that frequent social
contact at the age of 60 can lower the risk of developing dementia later on.
The link between having a rich social life and brain health has received much attention in the
scientific community.
Some studies have suggested that levels of social interaction can predict cognitive decline and
even dementia, while others have shown that group socializing can prevent the harmful effects of
aging on memory.
New research examines the link between social contact and dementia in more depth. Andrew
Sommerlad, Ph.D., from the Division of Psychiatry at University College London (UCL), in the
The United Kingdom is the first and corresponding author of the new study.
Sommerlad and colleagues started from a critical observation of existing studies. They say that
numerous findings have suggested that frequent social contact can protect the brain, either by
helping to build a cognitive reserve, or by reducing stress and promoting more healthful
behaviors.
Many longitudinal studies have found an increased risk of dementia and cognitive decline in
people with a smaller social network or less frequent social contact. However, the authors note,
most of these studies had a follow-up period of fewer than 4 years.
Furthermore, a lot of these observational findings could be biased by reverse causation, which
means that social isolation may be an effect rather than a cause of dementia.
In light of the above, Sommerlad and colleagues decided to investigate the link between
dementia and social contact over a much longer period — 28 years.
The results appear in the journal PLOS Medicine.
Sommerlad and the team carried out a retrospective analysis of a prospective cohort study called
Whitehall II.
Whitehall II included 10,308 participants who were 35–55 years old at the beginning of the
the study, 1985–1988.
The participants were clinically followed until 2017. During this period, 10,228 of the
participants reported on their social contact six times, through a questionnaire that asked about
relationships with relatives and friends living outside of their household.
The cognitive status of the participants was assessed five times, using standard tests of verbal
memory, verbal fluency, and reasoning."

To determine the occurrence of dementia, the researchers looked at three clinical and mortality
databases.
They applied Cox regression models with inverse probability and adjusted the analyses for & age,
sex, ethnicity, socioeconomic status, education, health behaviors, employment status, and marital
status.
The study found that more frequent social contact at age 60 with friends, but not relatives,
correlated with lower dementia risk.
Specifically, a person who saw friends almost every day at the age of 60 had a 12% lower risk of
developing dementia later on, compared with someone who only saw one or two friends once
every few months.
We’ve found that social contact in middle age and late-life appears to lower the risk of dementia.
This finding could feed into strategies to reduce everyone's risk of developing dementia, adding
yet another reason to promote connected communities and find ways to reduce isolation and
loneliness.