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

暴露於神經毒物的台灣老年人其記憶缺失及記憶抱怨的評估

神經毒物例如多氯聯苯(Polychlorinated biphenyls-PCBs)或多慮芙喃(polychlorinated dibenzofurans-PCDFs)，主要影響神經系統功能運作。近年來研究發現暴露於上述毒物的成年人會有記憶及學習障礙，但很少研究這些人是否會有記憶障礙、主觀記憶抱怨及自主生理狀況不良的情形。本研究希望了解神經毒物，對於易感族群的老年人，是否會影響其記憶功能、主觀記憶抱怨，或生理身體狀況不良的情形。本回溯性研究為1979年台灣“油症”暴露患者，其中年齡≧60歲之老年人為收案對象，並重新訪談及測試。我們使用結構性且信效度良好的問卷，及中文版魏氏智力測驗第三版(WAIS-R-III)，還有魏氏記憶評估修訂版(WMS-R)作為主要工具。記憶功能含符號特徵(Digit Span)，視覺記憶(Visual Memory Span)，注意力及數字廣度(Attention and Digit Span)，語言記憶測試(Verbal Memory Recalls)，學習能力(leaning ability)，30分鐘回憶測試(30-minute delayed recall)，及主觀記憶抱怨等(subjective memory complaints)評估。從328樣本數中，166人為暴露者，及162人為非暴露者。暴露組比起非暴露組有較多的身體生理狀況抱怨，諸如指甲變型、貧血、氣喘、高血壓、及皮質角化，呈顯著性差異。此外記憶功能如ADS，VMS，學習能力，語言記憶的第4,5次測試，及30分鐘回憶測試等，兩者亦呈顯著性差異(p < 0.05)。而主觀記憶抱怨和VMR (p = 0.04)及ADS (p = 0.03) 亦呈正相關性。本世代追蹤中研究中，暴露於神經毒物如PCBs/PCDFs 的老年人，其主觀身體生理功能抱怨、記憶功能評估及主觀記憶抱怨，皆比未暴露者來得多。結論顯示過去暴露於神經毒物的患者，容易導致身體上的、精神上的負擔，以及記憶功能之缺失。研究說明環境汙染應該預防勝於治療。

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.