Exposure to cycad genotoxins during early human brain development might be an important driver of the ensuing pathological features of ALS/PDC, comparable to HD where a mutant gene (Htt) perturbs neurodevelopment that results in age-related decline in cognitive function (Ruzo et al., 2018; van der Plas et al., 2019; Barnat et al., 2020; Hickman et al., 2021; Schultz et al., 2021). Here, PDC is linked to amyotrophic lateral sclerosis.