While 10% of ALS cases are associated with genetic mutations, the rest may have environmental causes. Higher than expected numbers of ALS cases have been identified near HABs in North Carolina using data from death certificates between 1999 and 2020 (unpublished). It is not clear why there might be more ALS cases near HABs. Blue-green algae produce toxins, such as β-methylamino-L-alanine, which are associated with neurotoxicity and ALS.

We hypothesize that there might be clinical differences in HAB-associated ALS and non-HAB-associated ALS, which may help to understand why this correlation exists and better manage HAB-associated ALS.