The study, published online May 3, 2023, by the Journal of the American Geriatrics Society, tracked more than 18,000 people (average age 55, 54% women) for an average of eight years. Every other year, researchers asked participants about their Internet use and administered cognitive testing. Nearly 65% of study participants reported being regular Internet users.
People who connected online for about two hours a day were about half as likely to develop dementia than those who didn't use the Internet regularly. The Internet users also maintained better verbal reasoning and memory. The benefits disappeared at high levels of Internet use — defined as six to eight hours a day.
The study authors speculated that online engagement could develop and maintain what's called cognitive reserve — the brain's ability to resist decline and find alternate ways to function efficiently. This could compensate for brain aging. But the study was observational — meaning it couldn't prove a cause-and-effect relationship between Internet use and dementia risk — and participants' Internet use was self-reported.
"If we take the findings at face value, this would mean Internet use is another cognitive activity that can keep your brain active and healthy, which can potentially increase thinking and memory skills in the short term and reduce the risk of dementia over the long term," says Dr. Andrew Budson, a lecturer in neurology at Harvard Medical School. More study is needed to determine if specific types of online activity might be related to health outcomes.