Memory Impairments and Memory Complaints in the Elderly Exposed to Neurotoxin in Taiwan

Neurotoxins, such as Polychlorinated biphenyls (PCBs) and polychlorinated dibenzofurans (PCDFs), affect central nervous system functioning. Recent studies have shown that elderly individuals exposed to these toxic compounds have reported memory and learning deficits. Little is known about the reported health status, memory function and memory complaints of these elderly individuals. This study aimed to evaluate memory-related issues and health conditions in elderly individuals exposed to neurotoxin of PCBs and/or PCDFs. We conducted a retrospective cohort study of the Yu-Cheng population in Taiwan. Registered subjects and matched controls (age ≥ 60 years) were recruited. We utilized self-reported health questionnaires and neuropsychological tests of the Wechsler Adult Intelligence Scale-Revised version in Chinese (WAIS-R-III) and the Wechsler Memory Scale-Revised (WMS-R). Memory modalities such as digit symbol (DS), visual memory span (VMS), attention and digit span (ADS), 5-trial verbal memory recalls (VMR), learning ability, 30-min delayed recall, and subjective memory complaints (SMCs) were evaluated. We analyzed a total of 328 subjects; 166 subjects were PCB/PCDF-exposed subjects and 162 were non-exposed subjects. The exposed elderly subjects were more likely to report health conditions such as nail deformity, anemia, asthma, hypertension, and hyperkeratosis. In addition, memory tests revealed a decline in ADS, VMS, learning ability, trial 4 and trial 5 of the VMR, and 30-min delayed recall test results in exposed subjects (p < 0.05). The SMCs correlated significantly with memory decline in the VMR (p = 0.04) and ADS (p = 0.03) tests. In the Taiwanese cohort, the elderly subjects exposed to PCBs/PCDFs reported more health problems, memory decline, and memory complaints. Our results provided evidence that exposure to neurotoxins may lead to physical and psychological burdens as well as memory complaints in future follow-ups. The results also demonstrated preventive strategies in environmental protection are more important than treatment after toxic exposure.