Neurocognitive changes among elderly exposed to PCBs/PCDFs in Taiwan

Area of Science:

• Environmental Health
• Neurotoxicology
• Epidemiology

Background:

• In 1979, 2,000 individuals in Taiwan were exposed to polychlorinated biphenyls (PCBs) and polychlorinated dibenzofurans (PCDFs) via contaminated cooking oil.
• Previous research indicated developmental and neurocognitive issues in children born to exposed mothers.
• The direct impact of PCB and PCDF exposure on the neurocognitive functioning of directly exposed individuals remained unclear.

Purpose of the Study:

• To compare the neurocognitive functioning of individuals directly exposed to PCBs and PCDFs with that of unexposed, age- and sex-matched neighbors.
• To investigate potential long-term neurocognitive effects of historical PCB and PCDF exposure.

Main Methods:

• A retrospective cohort study design was employed, including exposed subjects and unexposed reference subjects aged 60 years and older.
• Prospective outcome measurements utilized a comprehensive neurocognitive assessment battery.
• Evaluated domains included general cognition, memory, learning, motor and sensory function, mood, and daily living activities.

Main Results:

• 162 exposed subjects and 151 reference subjects completed the study.
• Exposed women exhibited reduced functioning in attention and digit span (ADS), visual memory span (VMS), and verbal memory recall (VMR), with impaired learning ability.
• A dose-response relationship was observed for VMR, ADS, and VMS, while exposed men showed no significant cognitive differences compared to the reference group.

Conclusions:

• Direct exposure to PCBs and PCDFs resulted in dose-dependent neurocognitive deficits in specific domains of attention, visual memory, and learning among women.
• No significant neurocognitive impairments were detected in men exposed to PCBs and PCDFs.
• Highlights sex-specific vulnerability to the long-term neurocognitive effects of persistent organic pollutant exposure.