Investigators followed more than 18,000 older individuals and found that regular Internet use was associated with about a 50% reduction in dementia risk, compared with their counterparts who did not use the Internet regularly.
They also found that longer duration of regular Internet use was associated with a reduced risk of dementia, although excessive daily Internet usage appeared to adversely affect dementia risk.
“Online engagement can develop and maintain cognitive reserve – resiliency against physiological damage to the brain – and increased cognitive reserve can, in turn, compensate for brain aging and reduce the risk of dementia,” study investigator Gawon Cho, a doctoral candidate at New York University School of Global Public Health, said in an interview.
The study was published online in the Journal of the American Geriatrics Society.
Prior research has shown that older adult Internet users have “better overall cognitive performance, verbal reasoning, and memory,” compared with nonusers, the authors note.
However, because this body of research consists of cross-sectional analyses and longitudinal studies with brief follow-up periods, the long-term cognitive benefits of Internet usage remain “unexamined.”
In addition, despite “extensive evidence of a disproportionately high burden of dementia in people of color, individuals without higher education, and adults who experienced other socioeconomic hardships, little is known about whether the Internet has exacerbated population-level disparities in cognitive health,” the investigators add.
Another question concerns whether excessive Internet usage may actually be detrimental to neurocognitive outcomes. However, “existing evidence on the adverse effects of Internet usage is concentrated in younger populations whose brains are still undergoing maturation.”
Ms. Cho said the motivation for the study was the lack of longitudinal studies on this topic, especially those with sufficient follow-up periods. In addition, she said, there is insufficient evidence about how changes in Internet usage in older age are associated with prospective dementia risk.
For the study, investigators turned to participants in the Health and Retirement Study, an ongoing longitudinal survey of a nationally representative sample of U.S.-based older adults (aged ≥ 50 years).
All participants (n = 18,154; 47.36% male; median age, 55.17 years) were dementia-free, community-dwelling older adults who completed a 2002 baseline cognitive assessment and were asked about Internet usage every 2 years thereafter.
Participants were followed from 2002 to 2018 for a maximum of 17.1 years (median, 7.9 years), which is the longest follow-up period to date. Of the total sample, 64.76% were regular Internet users.
The study’s primary outcome was incident dementia, based on performance on the Modified Telephone Interview for Cognitive Status (TICS-M), which was administered every 2 years.
The exposure examined in the study was cumulative Internet usage in late adulthood, defined as “the number of biennial waves where participants used the Internet regularly during the first three waves.”
In addition, participants were asked how many hours they spent using the Internet during the past week for activities other than viewing television shows or movies.
The researchers also investigated whether the link between Internet usage and dementia risk varied by educational attainment, race-ethnicity, sex, and generational cohort.
Covariates included baseline TICS-M score, health, age, household income, marital status, and region of residence.