GBA1 and dementia: Finally, the frequency of hallucinations, which again have been shown to be a risk factor for dementia in PD30, was increased in GBA1 mutation carriers (27.1% vs 15.5%; χ2 = 3.9, df = 1, 95% CI = −0.02–0.25, P = 0.049), albeit the association of GBA1 mutations with hallucinations was not significant after correcting for confounders.