贵州省汉、布依族老年人群甲状腺功能减退与轻度认知功能障碍关系的前瞻性队列研究

To discern the risk factors of mild cognitive impairment(MCI) and to avoid exposing was an important path to prevent dementia in elderly. Accumulating evidences have shown that hypothyroidism increased the risk of dementia disease in elderly incidence, and hypothyroidism may resulted in elderly patients’ mild cognitive impairment. But in recently years, based on community population research indicated that hypothyroidism was not associated with cognitive impairment. It is also uncertain whether hypothyroidism have any effect on mild cognitive impairment among elderly people, so we need more research evidences to confirm the relationship, especially evidence from prospective cohort studies based on community large sample population. Some research evidences also indicated that hypothyroidism prevalence was different with differential ethnical characteristic, and minority population had higher prevalence than Han people. Bouyei minority mainly lived in Guizhou province, but now there is little epidemical research of hypothyroidism prevalence or hypothyroidism effected on elderly people’s cognitive impairment. So we would study on the association between hypothyroidism and mild cognitive impairment among Han and Bouyei elderly population in Guizhou province. First, using cross section investigation to screen hypothyroidism and mild cognitive impairment patients among Han and Bouyei elderly population in Guizhou rural areas. Second, using prospective cohort study, we plan to follow-up the outcome of patients with hypothyroidism after excluded patients with mild cognitive impairment or Alzheimer's disease to explore the association between hypothyroidism and mild cognitive impairment by analyzing and comparing each other among Han and Bouyei elderly population. Our study could further confirm the association between hypothyroidism and mild cognitive impairment and to provide scientidic evidence to improve early intervention and prevention of cognitive impairment for hypothyroidism patients.

早期识别轻度认知功能障碍（MCI）危险因素并减少其暴露是预防老年期痴呆的重要途径和措施。有研究证实，甲状腺功能减退可增加老年痴呆发生风险，甲状腺功能减退可能致老年人认知功能受损，但近年社区人群的现况研究表明，甲状腺功能减退或亚临床甲减与MCI之间并没有关联，因此，两者之间关系需要进一步深入研究。流行病学调查显示，甲状腺功能减退流行存在民族差异，贵州省是我国布依族主要聚居地，至今没有关于老年人甲状腺功能减退及其对MCI发病影响的流行病学研究。为此，本次拟在贵州省农村地区开展汉、布依族老年人进行甲状腺功能和认知功能的现况研究，在此基础上，筛选甲状腺功能减退不同暴露情况、且认知功能正常人群作为研究对象，进行前瞻性队列研究，随访对象2年后MCI发生情况，定量分析并比较汉族、布依族人群中甲状腺激素水平与MCI发生风险的关系，为甲状腺功能减退患者早期干预及预防老年人认知功能减退提供科学依据。

背景：探讨老年人认知功能受损的危险因素并及时干预是预防老年痴呆的重要策略。基于体内体外实验研究证实了甲状腺激素异常可致认知功能受损，老年人群甲状腺功能减退的流行率较高，尤其是贵州少数民族地区人群，在该人群中研究甲状腺功能减退与轻度认知功能受损（mild cognitive impairment, MCI)的关联可为老年痴呆预防提供依据。本研究在贵州汉、布依族人群中探讨甲状腺功能减退与认知功能的关联及差异，为预防MCI及老年痴呆的发生提供科学依据。主要研究内容：一是现况调查贵州汉、布依族人群甲状腺功能减退和MCI的流行情况，分析两个民族中关联是否存在差异，并进一步探讨贵州农村社区老年人甲状腺功能减退与MCI的现况关联；二是随访调查分析，比较汉、布依族人群甲状腺功能减退与MCI发病的关联，分析两民族之间是否存在差异。主要结果及数据：汉族甲状腺功能减退（OH）患病率为6.3% （95%CI：4.5~8.2%），亚临床甲减（SCH）患病率为16.5% （95%CI：13.7~19.3%）；布依族OH患病率为3.5% （95%CI：1.9~5.2%），SCH患病率为13.0% （95%CI：10.0~16.0%），汉族和布依族民族甲减、亚临床甲减总体构成存在统计学差异（χ2=7.57，P=0.023）。基于现况结果显示，汉族、布依族老年人OH、SCH与老年人MCI均无统计学关联；在汉族老年人血清甲状腺激素中FT3水平与MMSE评分存在关联，且血清FT3高水平老年人MCI患病风险较低，但在布依族老年人没有观察相同结果。在农村社区老年人中，血清FT3和TSH水平与认知功能MMSE评分存在正关联。进一步随访研究结果显示，老年人MCI的发病率较高；与基线甲状腺功能正常老年人相比，OH和SCH并没有增加MCI发生的风险。科学意义：贵州汉、布依族老年人甲状腺功能减退的患病率较高，老年人群甲状腺功能减退并没增加轻度认知功能受损发病的风险。老年人甲状腺激素FT3和TSH水平与认知功能之间存在正关联，由于FT3与TSH存在调节的负反馈调节机制，这可能导致即使老年人甲状腺功能减退并没有增加MCI发病风险，研究结果为老年人认知功能下降的防治提供科学依据。