Internet Use a Modifiable Dementia Risk Factor?

Self-reported, regular internet use, but not overuse, in older adults is linked to a lower dementia risk, new research suggests.

Investigators followed over 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, New York City, told Medscape Medical News.

The study was published online May 3 in the Journal of the American Geriatrics Society.

Unexamined Benefits

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, since 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."

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 US-based older adults (age ≥ 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.

U-Shaped Curve

Over half of the sample (52.96%) showed no changes in internet use from baseline during the study period, while one fifth (20.54%) did show changes in use.

Investigators found a robust link between internet usage and lower dementia risk (cause-specific hazard ratio [csHR], 0.57 [95% CI, 0.46 - 0.71]) — a finding that remained even after adjusting for self-selection into baseline usage (csHR, 0.54 [0.41 - 0.72]) and signs of cognitive decline at baseline (csHR, 0.62 [0.46 - 0.85]).

Each additional wave of regular internet usage was associated with a 21% decrease in the risk of dementia [95% CI, 13% - 29%], wherein additional regular periods were associated with reduced dementia risk (csHR, 0.80 [95% CI, 0.68 - 0.95]).

"The difference in risk between regular and non-regular users did not vary by educational attainment, race-ethnicity, sex, and generation," the investigators note.

A U-shaped association was found between daily hours of online engagement, wherein the lowest risk was observed in those with 0.1 to 2 hours of usage (compared with 0 hours of usage). The risk increased in a "monotonic fashion" after 2 hours, with 6.1 to 8 hours of usage showing the highest risk.

This finding was not considered statistically significant, but the "consistent U-shaped trend offers a preliminary suggestion that excessive online engagement may have adverse cognitive effects on older adults," the investigators note.

"Among older adults, regular internet users may experience a lower risk of dementia compared to non‐regular users, and longer periods of regular internet usage in late adulthood may help reduce the risks of subsequent dementia incidence," said Cho. "Nonetheless, using the internet excessively daily may negatively affect the risk of dementia in older adults."

Bidirectional Relationship?

Commenting for Medscape Medical News, Claire Sexton, DPhil, Alzheimer's Association senior director of scientific programs and outreach, noted that some risk factors for Alzheimer's or other dementias can't be changed, while others are modifiable, "either at a personal or a population level."

She called the current research "important" because it "identifies a potentially modifiable factor that may influence dementia risk."

However, cautioned Sexton, who was not involved with the study, the findings cannot establish cause and effect. In fact, the relationship may be bidirectional.

"It may be that regular internet usage is associated with increased cognitive stimulation, and in turn reduced risk of dementia; or it may be that individuals with lower risk of dementia are more likely to engage in regular internet usage," she said. Thus, "interventional studies are able to shed more light on causation."

The HRS (Health and Retirement Study) is sponsored by the National Institute on Aging and is conducted by the University of Michigan. Cho, her coauthors, and Sexton have disclosed no relevant financial relationships.

J Am Geriatr Soc. Published online May 3, 2023. Abstract

Batya Swift Yasgur, MA, LSW, is a freelance writer with a counseling practice in Teaneck, New Jersey. She is a regular contributor to numerous medical publications, including Medscape and WebMD, and is the author of several consumer-oriented health books as well as "Behind the Burqa: Our Lives in Afghanistan and How We Escaped to Freedom" (the memoir of two brave Afghan sisters who told her their story).

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