Internet Use Maintains Cognitive Function among middle- and old-aged Chinese: A Five-year Longitudinal Study.

Background: Cognitive decline poses one of the greatest global challenges for health and social care, particularly in China, where the burden on the elderly population is most pronounced. Despite the rapid expansion of internet access, there is still limited understanding of the long-term cognitive impacts of internet usage among middle-aged and elderly individuals.

Objective: This study aims to explore the association between internet usage and age-related cognitive decline among middle- and old-aged Chinese. To gain a more comprehensive understanding of the effects of internet usage, we also focused on assessing the impact of both the frequency of internet use and the types of internet devices on cognition. Moreover, we assessed the mediating role of internet usage on cognitive function for characteristics significantly linked to cognition in stratified analysis.

Methods: We analyzed data based on 12,770 dementia-free participants aged ≥ 45 years from the China Health and Retirement Longitudinal Study. We employed a fixed-effects model to assess the relationship between internet usage and cognitive decline, and further validated it using multiple linear regression, generalized estimating equations (GEE), propensity score matching (PSM), inverse probability of treatment weighting (IPTW), and overlap weighting (OW). We further examined the varying effects of internet device type and frequency on cognitive function using fixed-effects models and Spearman's rank correlation. The Karlson-Holm-Breen (KHB) method was used to estimate the mediating role of internet usage in the urban-rural cognitive gap.

Results: Participants using the internet (n=1,005) were younger, more likely to be male, more educated, married, retired, living in an urban area, and had higher cognitive assessment scores compared with non-users (n=11,765). After adjusting for demographic and health-related risk factors, there was a positive correlation between internet use and cognitive function (β=0.551, 95% CI 0.391 to 0.710). Over the follow-up period, persistent internet users had a markedly lower 5-year incidence of neurodegenerative diseases at 2.2% (15/671) compared with non-users at 5.3% (379/7,099; P<.001). The negative impact of aging (> 50) on cognitive function was consistently less pronounced among internet users compared to non-users. Furthermore, increased frequency of internet usage was associated with greater cognitive benefits for middle-aged and elderly individuals (rs = 0.378, P<.001). Among digital devices used for internet access, cellphones (β=0.398, 95% CI 0.283 to 0.495) seem to have a higher level of cognitive protection compared to computers (β=0.147, 95% CI 0.091 to 0.204). The urban-rural disparity in cognitive function was partially attributed to the disparity in internet use (34.2% of the total effects, P<0.001).

Conclusions: This study reveals that the use of internet by individuals aged 45 years and older is associated with a reduced risk of cognitive decline. Internet usage has the potential to be a viable, cost-effective, non-pharmacological intervention for cognitive decline among middle-aged and elderly individuals.

Clinicaltrial: