Associations between Pre-Disease Biomarkers of Persistent Organic Pollutants and Amyotrophic Lateral Sclerosis Survival in the Danish Diet, Cancer and Health Study Cohort.
OBJECTIVE Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the degeneration of motor neurons in the brain and spinal cord. Most patients survive 3 to 5 years after diagnosis, although some live 10 years or more. Prognostic factors are incompletely understood, but previous case-control studies suggest that exposure to persistent organic pollutants (POPs) may be associated with ALS survival, but this has not been explored within prospective analysis of POP biomarkers. In this study, we aimed to prospectively investigate the relationship between exposure to POPs-assessed in pre-disease plasma samples-and survival with ALS in the Danish Diet, Cancer, and Health study cohort. METHODS We identified 166 incident ALS cases using the Danish National Patient Register via International Classification of Diseases (ICD) codes. We measured concentrations of 13 polychlorinated biphenyls (PCBs), 9 organochlorine pesticides, and 3 polybrominated diphenyl ethers in plasma samples collected at inclusion in the study (baseline). To assess the relationship between POP exposures and ALS survival, we used separate Cox models for each POP group adjusting for diagnosis age, sex, smoking status, body mass index, and marital status. We selected the most relevant POP groups for ALS survival using an elastic net penalized Cox proportional hazards regression model and then ran a model using a summary environmental risk score (ERS). RESULTS Single-pollutant Cox models showed that exposure to non-dioxin like PCBs, hexachlorobenzene (HCB), β-hexachlorocyclohexane (β-HCH), and chlordane compounds were associated with shorter survival. Elastic net penalized Cox proportional hazards regression selected HCB and chlordane compounds as the most relevant POPs for survival. The ERS Cox model showed a significant association with shorter survival (hazard ratio [HR]: 1.4, 95% confidence interval [CI]: 1.1-1.7). A 1 standard deviation (SD) higher ERS score was associated with an HR for death of 1.4 (95% CI: 1.1-1.7). Predicted median survival for those with an ERS score 1 SD higher than the mean was 12 months shorter (26 vs 38 months). INTERPRETATION Our study suggests that pre-disease exposure to some POPs such as HCB and chlordane compounds could negatively influence ALS survival. ANN NEUROL 2026.