Impairments of memory and learning in older adults exposed to polychlorinated biphenyls via consumption of Great Lakes fish.

Abstract

An association between in utero polychlorinated biphenyl (PCB) exposure and impaired childhood intellectual functioning has been reported, but the potential impact of PCB exposure during adulthood on intellectual functioning has received little attention. We assessed the impact of PCBs and other fish-borne contaminants on intellectual functioning in older adults. The subjects were 49- to 86-year-old Michigan residents recruited from an existing cohort. Fish eaters ate > 24 lb of sport-caught Lake Michigan fish per year and non-fish eaters ate < 6 lb of Lake Michigan fish per year. A battery of cognitive tests including tests of memory and learning, executive function, and visual-spatial function was administered to 180 subjects (101 fish eaters and 79 non-fish eaters). Blood samples were analyzed for PCBs and 10 other contaminants. We evaluated cognitive outcomes using multiple regression. PCBs and dichlorodiphenyl dichloroethene (DDE) were markedly elevated in fish eaters. After controlling for potential confounders PCB, but not DDE, exposure was associated with lower scores on several measures of memory and learning. These included the Weschler Memory Scale verbal delayed recall (p = 0.001), the semantic cluster ratio (p = 0.006), and list A, trial 1 (p = 0.037), from the California Verbal Learning Test. In contrast, executive and visual-spatial function were not impaired by exposure to either PCBs or DDE. In conclusion, PCB exposure during adulthood was associated with impairments in memory and learning, whereas executive and visual-spatial function were unaffected. These results are consistent with previous research showing an association between in utero PCB exposure and impairments of memory during infancy and childhood.

Comparing Mini-Mental State Examination and Attention and Digit Span in elderly exposed to polychlorinated biphenyls and polychlorinated dibenzofurans

“…The CNS involvement related to the hippocampus as memory and learning, but not cortical domains, was emphasized by several animal and epidemiological studies. [12][13][14][15][16] The deficits in attention and learning abilities show that PCB/PCDF neurotoxins can interfere with the integrity of short-term memory recalls, as in the present study. These results suggested that different neurotoxin might have a specific or different neurocognitive influence.…”

“…Schantz et al reported an existing cohort in 2001 of adult sport-caught fish-eaters exposed to PCB who had impaired memory and learning. 15 The results of that study were similar to the results in Taiwanese adults, with cognitive decline limited to memory and learning ability, but not relevant to executive or sensory functions. 16 Experimental studies have shown that PCB have effects on the cortical and subcortical brain.…”

“…31 Further investigations of sex-linked or estrogen influence to toxic effects are required. In addition, a longitudinal study of the adult sport-caught fish-eaters 15 had also shown learning and memory deficits. The differences between both papers included a different sample size (316 to189), an older cohort (69.5 to 64.3 years) and a higher mean PCB blood level (78.3 to 7.9 ppb) in the present study.…”

Understanding the human health effects of chemical mixtures.

“…On the other hand, Grandjean et al (31) studied the population of the Faroe Islands, who also eat a lot of fish, and reported significant decrements of IQ and abnormalities of behavior in children that increase with exposure levels. We have some evidence that adults who eat a significant amount of contaminated fish suffer from some cognitive deficits, attributed in different regions to methyl mercury by Mergler et al (32) and to PCBs by Schantz et al (33). One major question is whether it is the methyl mercury or the PCBs, both of which are present in most situations, that cause these effects, or whether perhaps it is the combination of the two.…”

Potential exposure to PCBs, DDT, and PBDEs from sport-caught fish consumption in relation to breast cancer risk in Wisconsin.

“…To our knowledge, no study has specifically evaluated breast cancer risk in consumers of diets potentially high in PCBs, DDT/DDE, and PBDEs such as consumers of high amounts of sport-caught fish, anglers, families who operate charter fishing boats, or native populations, although several other health parameters, including fecundability (Buck et al 2000;McGuinness et al 2001), birth size (Fein et al 1984), puberty growth (Gladen et al 2000), and cognitive functioning (Jacobson et al 1990;Schantz et al 2001), have been investigated in these adult subpopulations as well as in children.…”