Older people are almost four times more likely to have shared fake news on Facebook than the younger generation, according to research published in the journal Science.

On average, American Facebook users over 65 shared nearly seven times as many articles from fake news domains as those aged between 18 and 29, researchers from NYU and Princeton found in the study, which also concluded sharing such false content was “a relatively rare activity”.

The researchers analysed the Facebook history of about 1,750 American adults, cross-referencing links they had posted with lists of fake news publishers. In doing so, they found the vast majority of users did not share any articles from fake news domains in 2016 – 8.5% of those in the study as a whole shared at least one link to a domain such as denverguardian.com, truepundit.com, or donaldtrumpnews.co.

These sites, and 18 others like them, made up the list of “intentionally or systematically factually inaccurate” stories the researchers defined as fake news. Sites that are “partisan or hyperpartisan”, such as the far-right Breitbart.com, were excluded from the list of fake news purveyors.

But of those who shared links from the 21 “mostly pro-Donald Trump” domains the researchers looked at, there were clear demographic differences.

Eighteen per cent of Republican users shared at least one link to a fake news site, compared with less than 4% of Democrats. The more conservative a user was, the more articles they shared – a finding attributed to the fact that fake news in 2016 was mostly pro-Trump, and “the tendency of respondents to share articles they agree with”.

Those who shared the most content in general were less likely to share fake news, suggesting the problem is not that some people “will share anything”, the paper said. Instead, people who share a large number of links are more media-savvy, and able to distinguish real from fake online.

That findings are backed up by the demographic data: over-65s, who came to the internet later in life, shared more than twice as many fake news articles as those in the second-oldest age group, even when controlling for ideology, education and the total number of links shared.

The authors wrote: “As the largest generation in America enters retirement at a time of sweeping demographic and technological change, it is possible that an entire cohort of Americans, now in their 60s and beyond, lacks the level of digital media literacy necessary to reliably determine the trustworthiness of news encountered online.

“Within this cohort, lower levels of digital literacy could be compounded by the tendency to use social endorsements as credibility cues. If true, this would imply a growing impact, as more Americans from older age groups join online social communities.”

A second possibility, they noted, is that the findings are a specific case of the general effect of ageing on memory. “Memory deteriorates with age in a way that particularly undermines resistance to ‘illusions of truth’,” the authors wrote.