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.

Spending time with friends could stave off dementia for those 60 and older.
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 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.
Studying social activity and dementia
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 study, in 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.