Repeated Dietary Exposure to Low Levels of Domoic Acid and Problems with Everyday Memory: Research to Public Health Outreach

Abstract

Domoic Acid (DA) is a marine-based neurotoxin. Dietary exposure to high levels of DA via shellfish consumption has been associated with Amnesic Shellfish Poisoning, with milder memory decrements found in Native Americans (NAs) with repetitive, lower level exposures. Despite its importance for protective action, the clinical relevance of these milder memory problems remains unknown. The purpose of this study was to determine whether repeated, lower-level exposures to DA impact everyday memory (EM), i.e., the frequency of memory failures in everyday life. A cross-sectional sample of 60 NA men and women from the Pacific NW was studied with measures of dietary exposure to DA via razor clam (RC) consumption and EM. Findings indicated an association between problems with EM and elevated consumption of RCs with low levels of DA throughout the previous week and past year after controlling for age, sex, and education. NAs who eat a lot of RCs with presumably safe levels of DA are at risk for clinically significant memory problems. Public health outreach to minimize repetitive exposures are now in place and were facilitated by the use of community-based participatory research methods, with active involvement of state regulatory agencies, tribe leaders, and local physicians.

Human Poisoning from Marine Toxins: Unknowns for Optimal Consumer Protection

“…Most patients improve within 24 h to 12 weeks, but when consumers develop serious neurological damage, they can die [ 45 ]. Autopsies of deceased individuals have shown brain damage characterized by neuronal necrosis and astrocytosis particularly in the hippocampus, a cerebral region associated with memory and learning, which leads to the diagnostic label: amnesic shellfish poisoning (ASP) [ 44 , 46 , 47 ]. Anterograde memory disorder was described as a prominent feature and was considered a hallmark of DA intoxication [ 48 ].…”

Biosynthesis of the neurotoxin domoic acid in a bloom-forming diatom

“…In humans, a high, single-exposure dose of DA can cause amnesic shellfish poisoning (ASP), which involves symptoms of amnesia, seizures, coma, and in extreme cases, death. Even chronic, low-level consumption of DA may lead to kidney damage, cognitive deficit, and impairment of fetal development, making DA outbreaks an important human health problem (7–10). Similar neurotoxic symptoms have been observed in birds and marine mammals such as sea lions, which suffer spatial memory impairment linked to DA consumption, likely leading to increases in sea lion strandings (11).…”

Preclinical Modeling of Exposure to a Global Marine Bio-Contaminant: Effects of In Utero Domoic Acid Exposure on Neonatal Behavior and Infant Memory

“…Recent results from an environmental epidemiology study focused on chronic, low dose DA exposure reported that the high consumption of razor clams (>15 per week) in adult members of three Native American tribes living on the Western coast of the U.S. was associated with significant memory decrements when compared to a reference group of non-consumers or low-consumers (Grattan et al, 2016b). Deficits in memory were significant enough to impact daily living skills (Grattan et al, 2018).…”