Department of Neurology, Qingdao Municipal Hospital, Qingdao University, Qingdao, 266071, China.
Department of Neurology and Institute of Neurology, Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Shanghai Medical College, Fudan University, 12th Wulumuqi Zhong Road, Shanghai, 200040, China.
BMC Med. 2022 Apr 25;20(1):132. doi: 10.1186/s12916-022-02331-2.
Data on the association between free-living daytime sunlight exposure and incident dementia are scarce. The objective is to evaluate whether the time spent in outdoor light is related to the dementia risk and to investigate whether the optimal duration varies with clinical parameters.
Data were from a prospective cohort of 362,094 UK Biobank participants. A questionnaire survey was conducted to investigate how many hours the participants spent outdoors on typical summer and winter days. A restricted cubic spline (RCS) was performed to explore the potential nonlinear relationship between sunlight exposure and the risk of dementia. We used multivariate Cox proportional hazard regression models to estimate the hazard ratios (HRs) for the associations between sunlight exposure and dementia outcomes, with the change points as a reference.
After a median follow-up of 9.0 years, 4149 (1.15%) individuals were diagnosed with dementia. RCS showed a J-shaped relationship between time spent in outdoor light and the dementia risk, with the lowest risk at three change points (1.5 h/day on average, 2 h/day in summer, and 1 h/day in winter). Cox hazard regression models showed a marked increase in risk at low exposure (HR=1.287, 95%CI 1.094-1.515) but a relatively slow increase at higher exposure (HR=1.070, 95%CI 1.031-1.10). Results are more pronounced among participants over 60 years old, females, and those with exactly 7 h of sleep every night.
Sunlight exposure had a J-shaped association with dementia risk. Giving detailed guidance on sunlight exposure can effectively prevent dementia.
关于自由活动白天日光暴露与新发痴呆之间的关系的数据很少。目的是评估户外活动时间与痴呆风险的关系，并研究最佳持续时间是否随临床参数而变化。
数据来自英国生物库 362094 名参与者的前瞻性队列研究。通过问卷调查，调查参与者在典型夏季和冬季的户外度过多少小时。采用限制性立方样条（RCS）探索日光暴露与痴呆风险之间的潜在非线性关系。我们使用多变量 Cox 比例风险回归模型来估计日光暴露与痴呆结果之间的关联的风险比（HRs），以变化点为参考。
在中位数为 9.0 年的随访后，4149 人（1.15%）被诊断为痴呆。RCS 显示户外活动时间与痴呆风险之间呈 J 形关系，在三个变化点（平均每天 1.5 小时，夏季每天 2 小时，冬季每天 1 小时）风险最低。Cox 风险回归模型显示，低暴露时风险明显增加（HR=1.287，95%CI 1.094-1.515），但高暴露时风险增加相对缓慢（HR=1.070，95%CI 1.031-1.10）。结果在 60 岁以上的参与者、女性和每晚睡眠时间正好为 7 小时的参与者中更为明显。
日光暴露与痴呆风险呈 J 形关联。给予日光暴露的详细指导可以有效预防痴呆。
