Self- and interviewer-reported cognitive problems in relation to cognitive decline and dementia: results from two prospective studies.

BACKGROUND: Little is known regarding the association of interviewer-reported cognitive problems (ICP) with age-related cognitive decline. We aimed to investigate the independent associations of ICP and the combined associations of ICP and self-reported cognitive problems (SCP) with subsequent cognitive decline and dementia in two prospective cohort studies. METHODS: We included 10,976 Chinese (age = 57.7 ± 8.7) and 40,499 European (age = 64.6 ± 9.4) adults without dementia from the China Health and Retirement Longitudinal Study (CHARLS) and the Survey of Health, Ageing, and Retirement in Europe (SHARE). Self-rated memory (5-point scale) and interviewer-rated frequencies of asking for clarification (6-point scale) were used to define SCP and ICP (dichotomized). Outcomes included objective cognitive test scores (z-score transformation) and incident dementia. Generalized estimating equation models were performed to evaluate mean differences in objective cognitive decline. Logistic and Cox regression models were used to estimate the relative risk of dementia. Results from two cohorts were pooled using the random-effects models. RESULTS: ICP was associated with faster cognitive decline in CHARLS (ßCHARLS = -0.025 [-0.044, -0.006] z-score/year). ICP and SCP were also independently associated with higher risk of dementia in two cohorts (pooled relative risk for SCP = 1.73 [1.30, 2.29]; pooled relative risk for ICP = 1.40 [1.10, 1.79]). In the joint analysis, participants with coexistence of SCP and ICP had the fastest cognitive decline (ßCHARLS = -0.051 [-0.080, -0.021]; ßSHARE = -0.024 [-0.043, -0.004]; pooled ß = -0.035 [-0.061, -0.009] z-score/year) and highest risk of dementia (ORCHARLS = 1.77 [1.42, 2.20]; HRSHARE = 2.94 [2.42, 3.59]; pooled relative risk = 2.29 [1.38, 3.77]). CONCLUSIONS: The study suggested that interviewer-reported cognitive problems may be early indicators of cognitive decline and dementia in middle-aged and older adults. A combination of self- and interviewer-reported cognitive problems showed the strongest associations with cognitive decline and dementia.

Dietary factors in relation to the risk of cognitive impairment and physical frailty in Chinese older adults: a prospective cohort study.

PURPOSE: The study aimed to investigate the independent associations of dietary factors with cognitive impairment (CI) and physical frailty (PF) among Chinese older adults. METHODS: This study included 10,734 participants (mean age = 78.7 years) free of CI and PF at baseline from the Chinese Longitudinal Health Longevity Survey. Dietary intake was collected using a simplified food frequency questionnaire every 3-4 years. The Chinese version Mini-Mental State Examination was used to assess cognition function, participants with a score below 18 were defined as CI. PF was defined using the activities of daily living, instrumental activities of daily living, and functional limitation-related questions. The outcome was defined as the first onset of either CI or PF. Competing risk models were used to estimate the corresponding hazard ratios (HRs) and the 95% confidence intervals (95% CIs). RESULTS: During the study follow-up (mean = 8.1 years), a total of 1220 CI cases and 1451 PF cases were newly identified. Higher frequency of fruits intake was associated with a lower hazard of CI (HR = 0.75, 95% CI 0.58-0.97), whereas higher intake of preserved vegetables demonstrated an opposite association (HR = 1.23, 95% CI 1.07-1.42). In terms of PF, we observed a lower risk associated with higher meat and poultry intake (HR = 0.72, 95% CI 0.61-0.88). In particular, a significant protective association of fish and aquatic products intake with PF was observed among participants with ≥ 28 natural teeth (HR = 0.52, 95% CI 0.27-0.99). CONCLUSION: Our findings suggest divergent roles of major dietary factors in the development of CI and PF among Chinese older adults.

Associations of vegetable and fruit intake with cognitive function and its decline: Two longitudinal studies.

OBJECTIVES: Previous studies suggested protective associations of vegetables and fruits (VF) intake with cognitive function, but evidence on specific types of VF was insufficient. METHODS: The current study included 4066 participants from 1997 to 2006 in the China Health and Nutrition Survey (CHNS) and 6170 participants from 2013 to 2020 in the Health and Retirement Study (HRS). Dietary intake (using 3-day 24-h dietary recalls in CHNS and food frequency questionnaire in HRS) and cognitive function (using the Telephone Interview for Cognitive Status-Modified, TICS-m) were measured. Linear mixed-effects models were used to estimate the beta coefficients (ß) and the 95% confidence intervals (CI) to evaluate the association of VF with cognitive function (z-score) and its decline. RESULTS: Highest intake of total VF was associated with better cognitive function and slower cognitive decline. Differences in cognitive function z-score between the highest and lowest tertiles of VF consumption were 0.039 (95% CI: 0.002, 0.076) for CHNS and 0.063 (95% CI: 0.026, 0.100) for HRS. The corresponding differences in annual cognitive decline were 0.011 (95% CI: 0.002, 0.021) and 0.012 (95% CI: 0.003, 0.020) units respectively. Vegetables and fruits showed independent associations with cognitive function and its decline. In specific VF subgroups, when comparing the highest to the lowest tertile intake, cruciferous vegetables (ß = 0.058, 95% CI: 0.017, 0.100 in CHNS and ß = 0.067, 95% CI: 0.032, 0.101 in HRS) and green leafy vegetables (ß = 0.036, 95% CI: -0.001, 0.073 in CHNS and ß = 0.082, 95% CI: 0.046, 0.117 in HRS) was associated with better cognitive function in both cohorts. Similarly, higher intake of dark-colored vegetables (ß = 0.019, 95% CI: 0.008, 0.030 for red/yellow vegetables in CHNS and ß = 0.004, 95% CI: 0.001, 0.007 for green leafy vegetables in HRS) were associated with slower cognitive decline in subsequent years. Moreover, rigorous sensitivity analyses confirmed the stability of the results. CONCLUSIONS: Our findings support the potential beneficial roles of VF, especially cruciferous vegetables, green leafy vegetables, and red/yellow vegetables, in maintaining cognitive function and slowing cognitive decline in middle-aged and older adults.