Relationship between social support and 7-year trajectories of cognitive decline: results from the China Health and Retirement Longitudinal Study.

BACKGROUND: Social support is associated with cognitive function at an older age, but how distinct dimensions of social support affect trajectories of cognitive decline in older Chinese adults remains unclear. METHODS: Using longitudinal data (waves 1-4) from the China Health and Retirement Longitudinal Study, 7-year trajectories of cognitive decline by various social support markers, including family support, financial support, public support and perceived support, were estimated using latent growth curve modelling for adults aged 60 and over (N=6795). RESULTS: After adjusting for baseline sociodemographics, behaviours, body mass index and health conditions, all social support markers were associated with baseline cognitive function, except for living with spouse. Participants living with spouse experienced a slower cognitive decline (0.069 per year, 95% CI 0.006, 0.133) than those who were not. A faster cognitive decline was associated with co-residing with children (-0.053 per year, 95% CI -0.104, -0.003), receiving ≥¥5000 from children (-0.095 per year, 95% CI -0.179, -0.011), receiving financial support from others (-0.108 per year, 95% CI -0.208, -0.008) and perceived support (-0.068 per year, 95% CI -0.123, -0.013). When all markers were mutually adjusted for, the associations of living with spouse and receiving financial support from others with cognitive decline disappeared. Stratifying by rural-urban residence, medical insurance and meeting children 1-3 times per month were associated with a slower rate of cognitive decline in urban residents but not in rural residents. CONCLUSION: Overall, our findings confirm that the effects of distinct domains of social support on cognitive decline vary. More equally good social security systems should be established in urban and rural China.