GBA1 and Cognitive impairment: Previous studies have used different classification schemes for GBA variants, but consistently show that the risk of cognitive impairment increases with the severity of GBA mutation.35,37,38 Contrary to our findings, several longitudinal studies showed no association with the GBA PD-risk mutations, although these were either small studies39 or grouped E326K and T369M together with synonymous or intronic variants,7,40 potentially diluting their effect.