Reproductive Factors, Lifestyle Behaviours and Cognitive Decline in Chinese Postmenopausal Women: A Cohort Study.

Abstract

To investigate the association of reproductive factors and their joint effects with lifestyle behaviours with cognitive decline in Chinese postmenopausal women. Community-based cohort study. Shanghai, China. We prospectively followed 1379 cognitively normal postmenopausal women aged ≥ 60 years for 1.8 years on average. Menopausal age, menarche age, parity, age at first live birth and breastfeeding duration were assessed at baseline. Associations between reproductive factors or their joint effects with lifestyle behaviours and cognitive decline were examined using logistic regression. The additive interaction was evaluated by the relative excess risk due to interaction (RERI) and the attributable proportion due to interaction (AP). Cognitive decline was defined as an annual decline in Mini-Mental State (MMSE) Examination score exceeding mean decline by 1.0 SD. The ORs (95% CIs) for cognitive decline were 2.55 (1.07, 6.06) for menopausal age < 46 years and 2.32 (1.11, 4.83) for menopausal age 46-50 years compared with menopausal age > 55 years. Meanwhile breastfeeding > 35 months (2.15, 1.02-4.51) and breastfeeding 24-35 months (2.31, 1.13-4.71) had higher risks of cognitive decline than breastfeeding < 12 months. Moreover, the combination of early menopause (≤ 50 years) and insufficient vegetable intake (1.84, 1.12-3.01), physical inactivity (2.11, 1.28-3.48), suboptimal sleep duration (2.15, 1.32-3.51), or an unfavourable composite lifestyle index (CLI) (1.76, 1.06-2.94) was associated with an increased risk of cognitive decline compared with the combination of late menopause (> 50 years) and each favourable lifestyle behaviour. Similarly, prolonged breastfeeding duration (> 23 months) combined with physical inactivity (2.10, 1.23-3.59), suboptimal sleep (2.11, 1.26-3.55), or an unfavourable CLI (2.16, 1.19-3.91) showed elevated risks compared with the combination of short breastfeeding duration (≤ 23 months) and each favourable lifestyle behaviour. In addition, we found additive interactions between early menopause and physical inactivity (RERI = 1.08, 95% CI: 0.37-1.80; AP = 0.51, 95% CI: 0.19-0.83), as well as between long breastfeeding duration and physical inactivity (RERI = 0.89, 95% CI: 0.15-1.63; AP = 0.42, 95% CI: 0.07-0.78). Unhealthy lifestyle behaviours may exacerbate cognitive decline in women with adverse reproductive factors.