A longitudinal study of a large group of older adults showed that regular internet users had approximately half the risk of dementia compared to their same-age peers who did not use the internet regularly. This difference remained even after controlling for education, ethnicity, sex, generation, and signs of cognitive decline at the start of the study. Participants using the internet between 6 minutes and 2 hours per day had the lowest risk of dementia. The study was published in the Journal of the American Geriatrics Society.
Public discussions about internet use often revolve around problematic internet use, particularly among children and adolescents. Studies often link large amounts of time spent on the internet with various adverse conditions. However, the internet also forms the backbone of modern economy and entertainment. It provides lots of cognitively engaging contents that is relatively easy to access.
Studies have shown that online engagement can make individuals more resilient against physiological damage to the brain that develops as people age. This can, in turn, help older adults compensate for brain aging and reduce the risk of dementia. In this way, internet use can help extend the cognitively healthy lifespan.
Indeed, previous studies have shown that internet users tend to have better overall cognitive performance, verbal reasoning, and memory than non-users. However, most of these studies did not track changes over time or tracked them for very short periods. Thus, it could not be determined whether internet use helps maintain cognitive functioning or whether individuals with better cognitive functioning were more likely to use the internet.
Study author Gawon Cho and his colleagues wanted to examine how the risk of developing dementia is associated with whether adults regularly use the internet. They were also interested in how this association changes over time and how the total period of internet use in late adulthood is associated with the risk of dementia. Finally, they wanted to see if there might be an adverse effect of excessive internet use by examining the association between the risk of dementia and the daily number of hours spent on the internet.
They analyzed data from the Health and Retirement study. The Health and Retirement Study is an ongoing longitudinal survey of a nationally representative sample of U.S. older-age adults. This study reports being representative of U.S. adults aged 50 and over.
The study authors analyzed data of 18,154 participants from this study. All were born before 1966. They were aged between 50 and 65 years at the start of the analysis period. The median follow period of participants whose data were analyzed in this study was 8 years, but it went up to 17 years with some. Data were mostly collected between 2002 and 2018.
The study interviewed participants every second year since 2002 about their internet usage (“Do you regularly use the World Wide Web, or the Internet, for sending and receiving e-mail or for any other purpose, such as making purchases, searching for information, or making travel reservations?”). Additionally, participants were asked about their daily hours of internet usage.
Assessments of dementia were also conducted every second year through a telephone interview (the modified Telephone Interview for Cognitive Status). Study authors calculated how long participants survived without dementia i.e., their age when they developed dementia. They used various demographic data about participants in their analysis as well.
Results showed that around 65% of participants were regular internet users and 35% were non-regular users. 21% changed their internet use habits during the study period, 53% did not change them. The remaining 26% either dropped out, died during the follow-up period or developed dementia. 5% of participants developed dementia during the study period, 8% died or experienced another event due to which they were excluded from further analysis.
Participants who were regular internet users at the start of the study had a 1.54% risk of developing dementia. In non-regular users of internet this risk was 10.45%. When time until the development of dementia was analyzed, results showed that the risk of dementia of regular internet users was 57% of the risk non-regular users had of developing dementia.
When analyses were limited to adults without signs of cognitive decline at the start of the study the risk of dementia of regular internet users was 62% of the risk of non-regular users. Finally, the relationship between dementia risk and daily hours of internet usage was U-shaped. Adults using the internet between 6 minutes and 2 hours per day had the lowest risk of dementia. This risk was much higher in adults who did not use internet at all (0 hours of use), but also increased gradually with more daily internet use beyond 2 hours.
“Our findings show evidence of a digital divide in the cognitive health of older-age adults. Specifically, adults who regularly used the internet experienced approximately half the risk of dementia than adults who did not, adjusting for baseline cognitive function, self-selection into baseline internet usage, self-reported health, and a large number of demographic characteristics,” the study authors concluded.
The study sheds light on the relationship between internet use and cognitive functioning. However, it also has limitations that need to be taken into account. Notably, the dementia assessment used in this study might not completely agree with clinical diagnoses of dementia. Additionally, the study included only individuals without dementia at the start of the study. This excluded individuals who developed dementia early. Results might not have been the same if such individuals, who are part of the general population, were included in the study.
The study, “Internet usage and the prospective risk of dementia: A population-based cohort study”, was authored by Gawon Cho, Rebecca A. Betensky, and Virginia W. Chang.