Department of Environment Health, Harvard School of Public Health, Boston, Massachusetts 02215, USA.
Environ Health Perspect. 2010 Apr;118(4):505-10. doi: 10.1289/ehp.0901115. Epub 2009 Nov 6.
Low-level exposure to lead and to chronic stress may independently influence cognition. However, the modifying potential of psychosocial stress on the neurotoxicity of lead and their combined relationship to aging-associated decline have not been fully examined.
We examined the cross-sectional interaction between stress and lead exposure on Mini-Mental State Examination (MMSE) scores among 811 participants in the Normative Aging Study, a cohort of older U.S. men.
We used two self-reported measures of stress appraisal--a self-report of stress related to their most severe problem and the Perceived Stress Scale (PSS). Indices of lead exposure were blood lead and bone (tibia and patella) lead.
Participants with higher self-reported stress had lower MMSE scores, which were adjusted for age, education, computer experience, English as a first language, smoking, and alcohol intake. In multivariable-adjusted tests for interaction, those with higher PSS scores had a 0.57-point lower (95% confidence interval, -0.90 to 0.24) MMSE score for a 2-fold increase in blood lead than did those with lower PSS scores. In addition, the combination of high PSS scores and high blood lead categories on one or both was associated with a 0.05-0.08 reduction on the MMSE for each year of age compared with those with low PSS score and blood lead level (p < 0.05).
Psychological stress had an independent inverse association with cognition and also modified the relationship between lead exposure and cognitive performance among older men. Furthermore, high stress and lead together modified the association between age and cognition.
低水平的铅暴露和慢性应激可能会独立影响认知。然而，心理社会应激对铅的神经毒性的修饰作用及其与衰老相关的认知能力下降的综合关系尚未得到充分研究。
我们在一项针对美国老年男性的队列研究——正常衰老研究中，检查了应激和铅暴露之间的横断面相互作用对 811 名参与者简易精神状态检查（MMSE）评分的影响。
我们使用了两种应激评估的自我报告测量方法——与他们最严重问题相关的应激自我报告和感知应激量表（PSS）。铅暴露的指标是血铅和骨（胫骨和髌骨）铅。
自我报告应激水平较高的参与者的 MMSE 评分较低，这一结果在调整了年龄、教育程度、计算机使用经验、母语为英语、吸烟和饮酒摄入等因素后仍然成立。在多变量调整的交互作用检验中，PSS 评分较高的参与者的血铅水平增加两倍，其 MMSE 评分比 PSS 评分较低的参与者低 0.57 分（95%置信区间，-0.90 至 0.24）。此外，与 PSS 评分较低和血铅水平较低的参与者相比，PSS 评分较高且血铅水平较高或两者皆高的组合与每增加一年年龄 MMSE 评分下降 0.05-0.08 相关（p<0.05）。
心理应激与认知能力呈独立的负相关，并且还改变了老年男性铅暴露与认知表现之间的关系。此外，高应激和铅共同改变了年龄与认知之间的关系。
