Neuropsychological & Thyroid Effects of Perfluorinated Compounds in Older Adults

Perfluorinated compounds (PFCs) are new and emerging chemicals of environmental concern that have neurobehavioral and thyroid effects in animals. Very few studies however, have evaluated whether they have similar effects in humans. <P> An epidemiological study is proposed to examine the association between exposure to PFCs and nervous system and thyroid function among older adults. It builds upon an ongoing study of polychlorinated biphenyls (PCBs), polybrominated biphenylethers (PBDEs), and dioxin-like compounds (DLCs) by adding PFCs to the profile of analytes being measured. <P> Older men and women were selected as the target populations because they are potentially sensitive subpopulations that are already at risk for age-related neurological deficits, a process that may be accelerated by neurotoxins. A total of 253 men and women between 55 and 74 years of age participated in the parent project from 2000-02, including interviews regarding local fish consumption, residential history, and other relevant variables. They also underwent a neuropsychological test battery capable of detecting subtle age-related changes in cognition, reaction time, fine motor control, olfactory function, and affective state, and donated a blood sample for congener-specific PCB analysis. Remaining serum was archived and analyzed in 2005-06 for PBDEs, DLCs, and thyroid hormones. <P> A total of 174 persons still have archived serum available. They will be contacted, and it is expected that 150 will give their consent for the analysis of PFCs. The serum PFC concentrations will be correlated with the neurobehavioral test scores and thyroid hormone data already collected to examine the neurological and endocrine effects of PFCs. To control for a comprehensive set of potentially confounding variables (including serum concentrations of organochlorine pesticides, blood lead and mercury), multiple regression analysis will be used. Based on animal experiments and our findings for PCBs and PBDEs in humans, we hypothesize that PFCs may cause subtle deficits in neuropsychological function, especially learning and memory. In addition, we hypothesize deficits in thyroxine (T4). It is also possible that PFCs may interact with PCBs, PBDEs, and DLCs, given their similar effects on the nervous and endocrine systems. <P> The proposed project will be the first to examine how PFCs affect nervous system and endocrine function in older adults and to explore how they may interact with PCBs, PBDEs, and DLCs. It is a multidisciplinary effort, with epidemiologists, statisticians, chemists, psychologists, and gerontologists collaborating in a comprehensive effort. <P> By utilizing an existing surveillance cohort and building upon body burden and outcome data already collected, the proposed project is a more efficient way of contributing to the establishment of a chemical mixtures database with human health endpoints than establishment of a new cohort and the requisite collection of new data. <P>PUBLIC HEALTH RELEVANCE: This study will examine how exposure to environmental chemicals affects nervous system function and thyroid hormones among 150 older men and women who live in upper Hudson River communities. Blood samples that have been stored from 2000-2002 will be analyzed for levels of perfluorinated compounds (PFCs), a new and emerging contaminant of environmental concern. The results of this chemical analysis will then be compared to the results of tests for learning and memory, attention, muscle coordination, mood, and sense of smell conducted on the same persons in 2000-2002 to determine if those with higher levels of PFCs and other chemicals in their blood performed more poorly than those with lower levels.