Occupational exposures to solvents and lead as risk factors foralzheimer’s disease: A collaborativere-analysis of case-control studies

A meta-analysis, involving the secondary analysis of original data from 11 case-control studies of Alzheimer’s disease, is presented for occupational exposures to solvents and lead. Three studies had data on occupational exposure to solvents. Among cases, 21.3% were reported to have been exposed; among controls, this figure was comparable(20.9%). This yielded a pooled matched relative risk of 0.76 (95% Cl: 0.47-1.23). Four studies had data on exposure tolead. Exposure frequencies were 6.1% in cases and 8.3% in controls. This resulted in a pooled matched relative risk of0.71 (95% Cl: 0.36-1.41). The meta-analysis was particularly useful in validating negative results from individual studies and in increasing the statistical power for the analysis of lead exposure, where stratum-specific cell sizes were frequently smaller than five in individual studies. However, since exposure in the various studies was ascertained in arather broad manner, prospective studies are recommended which focus on high-risk occupational populations andwhich determine the incidence of Alzheimer’s disease in these and comparable unexposed populations.