# Association between cognitive function and smartphone ownership among Japanese very old adults: a cross-sectional and longitudinal study

## TL;DR

This study explores how smartphone ownership relates to cognitive function in very old Japanese adults, finding that better cognitive function is linked to owning a smartphone.

## Contribution

The study uniquely combines cross-sectional and longitudinal analyses to explore smartphone ownership's association with cognitive function and care levels in very old adults.

## Key findings

- Smartphone ownership was associated with higher MMSE scores (≥27) in adjusted analyses.
- No significant link was found between smartphone ownership and long-term care certification levels.
- Cognitive decline may hinder smartphone ownership among very old adults.

## Abstract

This research was conducted to investigate the association between cognitive function and smartphone ownership among very old adults, a rapidly growing age group. Additionally, we conducted a longitudinal investigation as a sub-analysis to determine whether owning a smartphone affects the level of long-term care certification as a proxy outcome for cognitive decline.

Data from a cross-sectional and longitudinal survey of the Kawasaki Aging and Wellbeing Project (KAWP) was used. Multivariate regression analysis was performed to examine the relationship between the Mini-Mental State Examination (MMSE) score and smartphone ownership. We also examined the association between smartphone ownership and the level of nursing care 1,278 days after the baseline.

Among 483 participants aged 85–90 years at baseline, 165 (46.9%) were male, and 131 (27.1%) owned a smartphone. In adjusted regression, smartphone ownership was associated with an MMSE score of ≥ 27 (odds ratio [OR]: 1.76, 95% confidence interval [CI]: 1.13–2.77), after controlling for potential confounders, including hypertension (OR: 1.65, 95% CI: 1.01–2.69). The results revealed no relationship between smartphone ownership and long-term care level.

Our results suggest that minimal cognitive decline in very old adults could make the ownership of a smartphone difficult.

The online version contains supplementary material available at 10.1186/s12877-025-06561-w.