Loneliness and trajectories of the cognition among Chinese middle and old-aged adults

Objectives Loneliness is widely regarded as a potential risk factor for cognitive decline, yet existing findings remain inconsistent. Analyzing longitudinal patterns of cognitive change, rather than relying on cross-sectional assessments, can provide deeper insights into the dynamic interplay between loneliness and cognitive health. This study explores the relationship between cognitive trajectories and loneliness in middle-aged and older adults across China. Methods The study analyzed data from 4,239 participants aged 45 and older, drawn from four waves (2011–2018) of the China Health and Retirement Longitudinal Study (CHARLS). Loneliness was measured using a single-item scale (1–4 points). Cognitive function was assessed using validated tests (recall, subtraction, figure drawing) standardized to population norms. Results Group-based trajectory modeling identified three distinct cognitive patterns: stable, slow decline, and rapid decline. After adjusting for covariates, binary logistic regression revealed a significant association between these cognitive trajectories and loneliness scores. Conclusion This study delineates three cognitive trajectories (stable, slow decline, rapid decline) in Chinese middle-aged and older adults. Individuals with rapid cognitive decline exhibited accelerated loneliness progression and significantly heightened risks of mild cognitive impairment and dementia.