"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," said senior author Gill Livingston, Professor at University College London.
The research, published in the journal PLOS Medicine, used data from the "Whitehall II" study, tracking 10,228 participants who had been 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 researchers referred to the study participants' electronic health records up until 2017 to see if they were ever diagnosed with dementia.
For the analysis, the research team focused on the relationships between social contact at age 50, 60 and 70, and subsequent incidence of dementia, and whether social contact was linked to cognitive decline, after accounting for other factors such as education, employment, marital status and socioeconomic status.
The researchers found that increased social contact at age 60 is 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 per cent 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.
"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," added Livingston.
