Digital and Health Literacy Are Associated with Health-Related Quality of Life Across Cognitive Impairment Stages in Older Adults

Background As South Korea transitions into an ultra-aged society, the prevalence of cognitive decline among older adults—including mild cognitive impairment (MCI) and Alzheimer's disease (AD)—continues to rise. Despite growing interest in digital therapeutics, the relationship between digital and health literacy and health-related quality of life (HRQoL) in cognitively impaired populations remains understudied. This study examined literacy profiles across cognitive groups and investigated whether digital and health literacy serve as predictors of HRQoL in older adults aged 65 and over. Methods A cross-sectional survey was conducted with 303 participants stratified into three groups: normal cognition (NC, n = 121), MCI (n = 88), and AD (n = 94). Participants were recruited from Boramae Hospital in Seoul. Digital literacy was assessed using mobile device experience, ability, attitude, and self-efficacy scales; health literacy was measured using the 44-item Health Literacy Questionnaire (HLQ); and HRQoL was evaluated using the EQ-5D-5L index and visual analogue scale (EQ-VAS). One-way ANOVA and multiple linear regression analyses were performed. Results Digital literacy demonstrated the strongest association with EQ-5D-5L index scores across the full sample (R² = .14), outperforming health literacy (R² = .058) and digital health literacy (R² = .093). Group differences were statistically significant for digital literacy, digital health literacy, and EQ-5D-5L index scores (all p < .001), as well as for health literacy ( p = .047). In the NC group, both digital and health literacy were significant predictors of EQ-5D-5L index scores ( β  = .27, p = .003 each). In the MCI group, digital literacy emerged as a significant predictor of EQ-VAS ( β  = .40, p < .001), while neither predictor reached significance for the EQ-5D-5L index. No significant literacy predictors were identified in the AD group. Conclusions Digital literacy is a meaningful predictor of HRQoL in older adults with intact or mildly impaired cognition, underscoring its potential as an intervention target in digital health strategies. The diminishing predictive role of literacy as cognitive decline progresses highlights the need for tailored, stage-specific approaches in the development of digital therapeutics for aging populations.