ObjectiveWe review empirical evidence for the relations of recent and cumulative lead dose with cognitive function in adults.Data SourcesA systematic search of electronic databases resulted in 21 environmental and occupational studies from 1996 to 2006 that examined and compared associations of recent (in blood) and cumulative (in bone) lead doses with neurobehavioral outcomes.Data extractionData were abstracted after consideration of exclusion criteria and quality assessment, and then compiled into summary tables.ConclusionsAt exposure levels encountered after environmental exposure, associations with bio-markers of cumulative dose (mainly lead in tibia) were stronger and more consistent than associations with blood lead levels. Similarly, in studies of former workers with past occupational lead exposure, associations were also stronger and more consistent with cumulative dose than with recent dose (in blood). In contrast, studies of currently exposed workers generally found associations that were more apparent with blood lead levels; we speculate that the acute effects of high, recent dose may mask the chronic effects of cumulative dose. There is moderate evidence for an association between psychiatric symptoms and lead dose but only at high levels of current occupational lead exposure or with cumulative dose in environmentally exposed adults.

We review several issues of broad relevance to the interpretation of epidemiologic evidence concerning the toxicity of lead in adults, particularly regarding cognitive function and the cardiovascular system, which are the subjects of two systematic reviews that are also part of this mini-monograph. Chief among the recent developments in methodologic advances has been the refinement of concepts and methods for measuring individual lead dose in terms of appreciating distinctions between recent versus cumulative doses and the use of biological markers to measure these parameters in epidemiologic studies of chronic disease. Attention is focused particularly on bone lead levels measured by K-shell X-ray fluorescence as a relatively new biological marker of cumulative dose that has been used in many recent epidemiologic studies to generate insights into lead’s impact on cognition and risk of hypertension, as well as the alternative method of estimating cumulative dose using available repeated measures of blood lead to calculate an individual’s cumulative blood lead index. We review the relevance and interpretation of these lead biomarkers in the context of the toxico-kinetics of lead. In addition, we also discuss methodologic challenges that arise in studies of occupationally and environmentally exposed subjects and those concerning race/ethnicity and socioeconomic status and other important covariates.

Early-life educational quality and literacy in late life explain a substantial portion of race-related disparities in late-life cognitive function.

There are many mandated school-based programs to prevent adolescent alcohol and drug (AOD) use, but few are voluntary and take place outside of class time. Objectives This cluster randomized controlled trial evaluates CHOICE, a voluntary after school program for younger adolescents, which reduced both individual- and school-level alcohol use in a previous pilot study. Methods We evaluated CHOICE with 9,528 students from 16 middle schools. The sample was 51% female; 54% Hispanic, 17% Asian, 15% white, 9% multiethnic and 3% African American. Fifteen percent of students attended CHOICE. All students completed surveys on alcohol beliefs and use at baseline and 6–7 months later. We conducted intention-to-treat (ITT) school-level analyses and propensity-matched attender analyses. Results Lifetime alcohol use in the ITT analysis (i.e., school level) achieved statistical significance, with an odds ratio (OR) of 0.70 and a number needed to treat (NNT) of 14.8. The NNT suggests that in a school where PC was offered, 1 adolescent out of 15 was prevented from initiating alcohol use during this time period. Although not statistically significant (p=.20), results indicate that past month alcohol use was also lower in PC schools (OR = 0.81; NNT = 45). Comparisons of attenders versus matched controls yielded results for lifetime use similar to school-wide effects (OR = 0.74 and NNT = 17.6). Conclusions Initial results are promising and suggest that a voluntary after school program that focuses specifically on AOD may be effective in deterring alcohol use among early adolescents; however, further research is needed as program effects were modest.