Smartphone use and cognitive performance in middle-aged and older adults: a cross-sectional study in China

Although increasing use of smartphones has been observed among middle-aged and older adults, its relationship with cognitive performance remains understudied in this population. This study included 10,846 individuals aged 45 and above who participated in the Kailuan study and undertook the cognitive function test by the Mini-Mental State Examination (MMSE) between 2016 and 2018. Information on smartphone use, including smartphone use status, time spent on smartphone daily, and before bedtime, was collected via questionnaires. Cognitive performance was evaluated by the MMSE. Multiple linear regression models were used to examine the association between smartphone use and cognitive performance, with difference in MMSE scores and 95% confidence intervals (CIs) estimated, adjusting for age, sex, education, income, and other potential confounders. Using smartphones was significantly associated with better cognitive function (mean difference = 0.57, 95% CI: 0.46–0.67). We further examined smartphone using time daily and before bedtime in smartphone users and evaluated their associations with cognitive function separately. Regarding daily smartphone using time, although individuals with daily using time (< 0.5 h) presented better cognitive function compared to non-smartphone users (mean difference = 0.73, 95% CI: 0.61–0.86), it showed a trend of declining mean difference with increased using time. Likewise, a similar pattern of longer duration of smartphone before sleep and poorer cognitive function was observed, where participants with smartphone use before bedtime ≥ 10 min showed comparable cognitive function with non-smartphone users. In this community-based study in China, we found that smartphone use was significantly associated with better cognitive performance among middle-aged and older adults. However, prolonged smartphone using time, especially before bedtime, could attenuate the observed positive association between smartphone use and cognitive function in this population. Future studies with longitudinal design are warranted to confirm our observations and explore the long-term impact of smartphone use on cognitive performance.