Previous studies have shown that older people's online engagement can help reduce cognitive decline, but they’ve only examined the short-term effects. The current study examined the long-term effects of internet usage on cognitive functioning and dementia risk.
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In normal brain aging, ‘fluid’ abilities such as problem-solving, mental speed, and spatial manipulation peak in the mid-20s and decline gradually until the age of 60, when they start to decline rapidly. In contrast, ‘crystallized’ abilities, including accumulated knowledge and expertise that relies on long-term memory, increase through work, cultural and life experiences, and education; they are less affected by aging and disease.
Cognitive decline in older adults refers to difficulties with thinking, memory and concentration. Dementia is usually diagnosed when cognitive decline has become severe enough to interfere with social and/or occupational functioning.
In this study, the researchers followed 18,154 adults without dementia aged between 50 and 65 for a maximum period of just over 17 years (the median time being around eight years). Participants’ cognitive functioning was tested during a twice-yearly interview where they were also asked how often they used the internet and separated into "regular" and "non-regular" users.
The researchers used their data to examine the association between internet usage and the time it took for regular and non-regular users to develop dementia. They also looked at the degree of daily internet usage and its effect on cognition.
The researchers found that the overall incidence rate of dementia during the study period was 4.7% and that there was a link between regular internet use and a lower risk of dementia. Regular use was associated with about half the risk of dementia compared with non-regular use and was not significantly influenced by educational level, race, ethnicity, or sex.
The lowest risk of dementia was seen in participants who used the internet for between six minutes and two hours a day. Whereas those with six to eight hours of usage showed the highest estimated risk, suggesting that excessive internet usage was bad for cognitive health.
The researchers say their study demonstrates the existence of a “digital divide” in cognitive health between older internet users based on their usage.
“Thus far, research on digital divide in cognitive health has been limited to cross-sectional or longitudinal examinations with short followups, and studies have only considered baseline internet usage,” the researchers said. “We fill these gaps by characterizing the relationship between the risk of dementia and baseline internet usage over a much longer period and also examining whether changes in usage are associated with subsequent cognitive performance.”
It's important to note that the correlation between internet usage and cognitive health found here does not equate to causation. While the researchers found a link between these two things, it doesn’t necessarily mean that less frequent internet usage causes dementia or that jumping online will help prevent it..
The researchers understand that a person’s online engagement may include a wide range of activities, from checking the news to sending emails and online shopping. They are hopeful that future research might identify a link between how a person uses the internet and their cognitive health.
The study was published in the Journal of the American Geriatrics Society.
