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[背景]震颤是最常见的神经症状之一,但人们对其病因仍知之甚少。病例对照研究表明,血液中的铅和特发性震颤之间存在关联,而且这种关联受到δ-氨基乙酰丙酸脱氢酶(ALAD)基因多态性的调节。[目的]在一项前瞻性队列研究中,同时使用血铅和骨铅(累积铅暴露的生物标志)检验铅和震颤之间的关系,其中包括ALAD的调节作用。[方法]测量VA标准老龄化研究队列中中老年男性(年龄范围50~98岁)的胫骨(n=670)和髌骨(n=672)中的骨铅以及血铅(n=807)。基于手工绘制样本的方法对震颤进行评分。ALAD基因型分为ALAD-2载体或非ALAD-2的载体两类。校正年龄、教育程度、吸烟和酒精的摄入量后,使用线性回归估计铅生物标志和震颤得分之间的关联。[结果]在未校正的分析中,所有铅生物标志的五分位数和震颤分数之间存在临界关联性(P<0.13),但在校正的模型中却无此现象。年龄是预测震颤的最强因子。在那些低于中位数年龄(68.9年)的研究对象中,震颤随血铅增加并具有显著性(P=0.03),但在骨铅中却不明显。没有发现ALAD的调节作用,也没有发现震颤评分随着时间的变化与骨铅之间的关联性。[结论]研究结果不能强有力地支持铅暴露和震颤之间的关联,与累积铅生物标志也没有关联,不过研究结果仍然提示在这一队列的较年轻者中血铅可能与震颤有关联。
[Background] Tremor is one of the most common neurological symptoms, but people still do not know much about its cause. Case-control studies have shown that there is a link between blood lead and essential tremor, and this association is regulated by delta-aminolevulinic acid dehydrogenase (ALAD) gene polymorphism. [Purpose] In a prospective cohort study, the relationship between lead and tremor was examined using both lead in blood and bone lead (a biomarker of accumulated lead exposure), including the regulatory role of ALAD. [Methods] Bone lead and blood lead (n = 807) in the tibia (n = 670) and patella (n = 672) were measured in the VA standard aging study cohort of middle-aged and elderly men (aged 50-98 years). Tremor was scored based on a hand-drawn sample. The ALAD genotype is divided into two groups, the ALAD-2 vector and the non-ALAD-2 vector. After adjusting for age, education, smoking and alcohol intake, a linear regression was used to estimate the association between lead biomarkers and tremor scores. [Results] There was a critical correlation (p <0.13) between the quintile and the tremor scores for all lead biomarkers in uncorrected analyzes, but not in the corrected model. Age is the strongest predictor of tremor. In subjects below the median age (68.9 years), tremors increased and were significantly associated with blood lead (P = 0.03), but not in bone lead. No modulation of ALAD was found and no association was found between the tremor score and bone lead over time. [Conclusions] The findings do not strongly support the association between lead exposure and tremor and are not associated with cumulative biomarkers of lead, but the results still suggest that blood lead may be associated with tremor in the younger cohort of this cohort.