Department of Epidemiology of Aging, Center for Gerontology and Social Science, National Center for Geriatrics and Gerontology, 7-430 Morioka-cho, Obu, Aichi, 474-8511, Japan.
Faculty of Health and Medical Sciences, Aichi Shukutoku University, Aichi, Japan.
Eur J Nutr. 2023 Jun;62(4):1719-1729. doi: 10.1007/s00394-023-03107-x. Epub 2023 Feb 17.
Evidence has suggested that adherence to a Japanese diet may be beneficial for health. However, its association with incident dementia remains unclear. The aim was to explore this association in older Japanese community-dwellers, taking apoprotein E genotype into consideration.
A 20-year follow-up cohort study involving 1504 dementia-free older Japanese community-dwellers (aged 65-82 years) living in Aichi Prefecture, Japan, was conducted. Based on a previous study, a 9-component-weighted Japanese Diet Index (wJDI9) score (range - 1 to 12) was calculated using 3-day dietary record data and used as an indicator of adherence to a Japanese diet. Incident dementia was confirmed by the Long-term Care Insurance System certificate, and dementia events occurring within the first 5 years of follow-up were excluded. A multivariate-adjusted Cox proportional hazards model was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for incident dementia, and Laplace regression was used to estimate percentile differences (PDs) and 95% CIs (expressed in months) in age at incident dementia (i.e., dementia-free duration differences), according to tertiles (T1-T3) of wJDI9 scores.
The median (IQR) follow-up duration was 11.4 (7.8-15.1) years. During the follow-up period, 225 (15.0%) cases of incident dementia were identified. Because the smallest prevalence of incident dementia was 10.7% for the T3 group of wJDI9 scores, to avoid inaccurately estimating the dementia-free duration of participants in the T3 group, the 11th PDs in age at incident dementia between the T1 and T3 groups of wJDI9 scores were estimated. A higher wJDI9 score was associated with a lower risk of incident dementia and a longer dementia-free duration difference. The multivariate-adjusted HR (95% CI) and 11th PDs (95% CI) in age at incident dementia for participants in the T1 vs. T3 group were 1.00 (reference) vs. 0.58 (0.40, 0.86), and 0 (reference) vs. 36.7 (9.9, 63.4) months, respectively. Each 1-point increase of the wJDI9 score was associated with a 5% lower risk of incident dementia (P value = 0.033) and 3.9 (0.3, 7.6) additional months of dementia-free duration (P value = 0.035). No differences were seen in sex or smoking status (current smoker vs. non-current smoker) at baseline.
These findings suggest that adherence to a Japanese diet defined by wJDI9 is associated with a lower risk of incident dementia in older Japanese community-dwellers, suggesting the benefit of the Japanese diet for dementia prevention.
有证据表明，遵循日本饮食模式可能对健康有益。然而，其与痴呆症发病的关联尚不清楚。本研究旨在探讨在日本社区居住的老年人中，考虑载脂蛋白 E 基因型后，这种关联是否存在。
本研究是一项为期 20 年的随访队列研究，共纳入了 1504 名居住在日本爱知县、年龄在 65-82 岁、无痴呆症的老年人。基于先前的一项研究，使用 3 天饮食记录数据计算了 9 个组成部分加权日本饮食指数（wJDI9）评分（范围为-1 至 12），作为对日本饮食模式的依从性的指标。通过长期护理保险系统的证明来确定痴呆症的发病情况，并且排除了随访前 5 年内发生的痴呆症事件。使用多变量调整的 Cox 比例风险模型计算了痴呆症发病的风险比（HR）和 95%置信区间（CI），并使用拉普拉斯回归估计了 wJDI9 评分三分位数（T1-T3）的年龄发病痴呆症的百分位数差异（PD）和 95%CI（以月表示），即发病前无痴呆症的时间差异（即痴呆症无时间差异）。
中位（IQR）随访时间为 11.4（7.8-15.1）年。在随访期间，共发生 225 例（15.0%）痴呆症发病。由于 wJDI9 评分 T3 组的最小发病痴呆症率为 10.7%，为避免对 wJDI9 评分 T3 组参与者的无痴呆症持续时间进行不准确的估计，我们估计了 wJDI9 评分 T1 组和 T3 组之间第 11 个 PDs。更高的 wJDI9 评分与较低的痴呆症发病风险和更长的无痴呆症持续时间差异相关。多变量调整后的 HR（95%CI）和第 11 个 PDs（95%CI）在 T1 组与 T3 组之间分别为 1.00（参考）与 0.58（0.40，0.86）和 0（参考）与 36.7（9.9，63.4）个月。wJDI9 评分每增加 1 分，痴呆症发病风险降低 5%（P 值=0.033），无痴呆症持续时间增加 3.9（0.3，7.6）个月（P 值=0.035）。在基线时，性别或吸烟状况（当前吸烟者与非当前吸烟者）没有差异。
这些发现表明，根据 wJDI9 定义的日本饮食模式与日本社区居住的老年人中痴呆症发病风险降低相关，提示日本饮食对预防痴呆症有益。
