The longitudinal study, published in the journal PLOS Medicine, provides the most robust evidence to date that social contact earlier in life could play an important role in staving off dementia.
“This finding could feed into strategies to reduce everyone’s risk of developing dementia”
Researchers used data from the Whitehall II study, tracking 10,228 people who were asked on six occasions between 1985 and 2013 about their frequency of social contact with friends and relatives.
The same participants also completed cognitive testing from 1997 onwards, and the researchers looked at electronic health records up until 2017 to see if they were ever diagnosed with dementia.
For the analysis, the researchers focused on the relationships between social contact at age 50, 60 and 70, and subsequent incidence of dementia.
Specifically, they looked at whether social contact was linked to cognitive decline, after accounting for other factors such as education, employment, marital status and socioeconomic status.
“People who are socially engaged are exercising cognitive skills such as memory and language”
The study authors found that increased social contact at age 60 was associated with a significantly lower risk of developing dementia later in life.
The analysis showed that someone who saw friends almost daily at age 60 was 12% less likely to develop dementia than someone who only saw one or two friends every few months.
They found similarly strong associations between social contact at ages 50 and 70 and subsequent dementia.
While those associations did not reach statistical significance, the researchers said that social contact at any age may well have a similar impact on reducing dementia risk.
Social contact in mid to late life was similarly correlated with general cognitive measures, according to the study led by University College London.
Previous studies have found a link between social contact and dementia risk, but they did not have such long follow-up times.
As a result, they could not rule out the possibility that the beginnings of cognitive decline may have been causing people to see fewer people, rather than the other way around.
“We now need to see ministers prioritise better support initiatives to help people reduce the risk of dementia”
The long follow-up in the new study strengthens the evidence that social engagement could protect people from dementia in the long run, noted those behind it.
The researchers highlighted that there were a few explanations for how social contact could reduce dementia risk.
Lead study author Dr Andrew Sommerlad said: “Here 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.”
Senior author Professor Gill Livingston added: “People who are socially engaged are exercising cognitive skills such as memory and language, which may help them to develop cognitive reserve – while it may not stop their brains from changing, cognitive reserve could help people cope better with the effects of age and delay any symptoms of dementia.
“Spending more time with friends could also be good for mental wellbeing, and may correlate with being physically active, both of which can also reduce the risk of developing dementia,” he said.
The study was conducted by researchers in UCL Psychiatry, UCL Epidemiology and Public Health, Camden and Islington NHS Foundation Trust and Inserm.
“We need more awareness of the benefits that social wellbeing and connectedness can have”
Fiona Carragher, chief policy and research officer at the charity the Alzheimer’s Society, said: “There are many factors to consider before we can confirm for definite whether social isolation is a risk factor or an early sign of the condition – but this study is a step in the right direction.
“As the number of people in the UK with dementia is set to rise to one million by 2021, we must do what we can to reduce our risk.
“The government’s recent emphasis on health prevention is a welcome opportunity to reduce the risk of dementia across society,” she said.
“We now need to see ministers prioritise better support initiatives to help people reduce the risk of dementia, and look forward to seeing this when the results of the green paper on prevention are published later in the year.”
Dr Kalpa Kharicha, head of innovation, policy and research at the Campaign to End Loneliness, said: “We welcome these findings that show the benefits of frequent social contact in late/middle age on dementia risk.
“We need more awareness of the benefits that social wellbeing and connectedness can have to tackle social isolation, loneliness and reduce dementia risk.”