UC Davis

Despite a global ban on their production, polychlorinated biphenyls (PCBs) remain widespread environmental contaminants and pose considerable risks to human health. Experimental findings demonstrate that PCBs have profound neurotoxic effects, with individual congeners varying in degrees of cytotoxicity and carcinogenicity. Exposure to PCBs is regarded as a probable risk factor for several neurological and psychiatric conditions of unknown etiology. Though more often investigated from a neurodevelopmental standpoint, PCB-induced neurotoxicity likely also has implications for adolescent- and adult-onset disease states. This review outlines significant findings of epidemiological studies that examined risks for neurodegenerative diseases and affective disorders in cases of adult PCB exposure. The biological plausibility of the observed associations between PCB exposure and increased risk for Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), Alzheimer’s disease (AD), and major depressive disorder (MDD) are discussed in the context of preclinical evidence supporting potential pathological mechanisms by which PCBs confer risk of neurodegenerative disease. Specifically, we focus on oxidative stress, altered neural connectivity, disrupted monoamine neurotransmitter homeostasis, and aggregated protein pathology. Lastly, key data gaps in the existing epidemiological literature are identified.