BACKGROUND In addition to affecting the oxygen supply to the brain, pulmonary function is a marker of multiple insults throughout life (including smoking, illness, and socioeconomic deprivation). In this meta-analysis of existing longitudinal studies, we tested the hypothesis that lower pulmonary function and respiratory illness are linked to an elevated risk of dementia. METHOD We conducted a systematic review of longitudinal studies using PubMed until April 1st, 2019 and, where possible, pooled results in random-effects meta-analyses. RESULTS We identified eleven studies relating pulmonary function to later dementia risk, and eleven studies of respiratory illness and dementia (including one which assessed both). The lowest quartile of Forced Expiratory Volume in one second (FEV1) compared with the highest was associated with a 1.4-fold (1.46, 95%CI 0.77-2.75) increased dementia risk (Ntotal=62,209, two studies). An decrease of one standard deviation in FEV1 was associated with a 28% increase in dementia risk (1.28, 95%CI 1.03-1.60; Ntotal=67,505; six studies). Respiratory illness was also associated with increased dementia risk to a similar degree (1.54, 1.30-1.81, Ntotal=288,641, 11 studies). CONCLUSIONS Individuals with poor pulmonary function experience increased risk of dementia. The extent to which the association between poor pulmonary function and dementia is causal remains unclear and requires examination.

中文翻译：

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呼吸系统疾病和肺功能降低是痴呆的危险因素：荟萃分析的系统评价

背景除了影响对大脑的氧气供应之外，肺功能是一生中多次受到损害（包括吸烟、疾病和社会经济剥夺）的标志。在这项对现有纵向研究的荟萃分析中，我们检验了以下假设：肺功能降低和呼吸系统疾病与痴呆风​​险升高有关。方法 我们使用 PubMed 对截至 2019 年 4 月 1 日的纵向研究进行了系统评价，并在可能的情况下将结果汇总到随机效应荟萃分析中。结果 我们确定了 11 项与肺功能与后期痴呆风险相关的研究，以及 11 项关于呼吸系统疾病和痴呆的研究（包括一项对两者进行评估的研究）。一秒内用力呼气量 (FEV1) 的最低四分位数与最高四分位数相比与 1.4 倍 (1.46, 95% CI 0.77-2.75) 增加痴呆风险（Ntotal=62,209，两项研究）。FEV1 降低一个标准差与痴呆风险增加 28% 相关（1.28，95%CI 1.03-1.60；Ntotal=67,505；六项研究）。呼吸系统疾病也与类似程度的痴呆风险增加相关（1.54、1.30-1.81、Ntotal=288,641、11 项研究）。结论 肺功能差的个体患痴呆症的风险增加。肺功能差与痴呆之间的因果关系在多大程度上尚不清楚，需要检查。呼吸系统疾病也与类似程度的痴呆风险增加相关（1.54、1.30-1.81、Ntotal=288,641、11 项研究）。结论 肺功能差的个体患痴呆症的风险增加。肺功能差与痴呆之间的因果关系在多大程度上尚不清楚，需要检查。呼吸系统疾病也与类似程度的痴呆风险增加相关（1.54、1.30-1.81、Ntotal=288,641、11 项研究）。结论 肺功能差的个体患痴呆症的风险增加。肺功能差与痴呆之间的因果关系在多大程度上尚不清楚，需要检查。