GBA1 and dementia: Key subtle traits of GBA1-PD have since emerged notably, an earlier age of onset by ~ 1.7–6.0 years, higher Unified Parkinson’s Disease Rating Scale Part III (UPDRS-III) scores, greater frequency of dementia, visual hallucinations and severity of NMSs, particularly depression (Neumann et al. 2009; Hu et al. 2010; Winder-Rhodes et al. 2013; Asselta et al. 2014; Zhang et al. 2018b).