SLC6A3 and Lewy body dementia: Probably the best‐described phenotype of pre‐dementia DLB is mild cognitive impairment with Lewy bodies (MCI‐LB), which can be distinguished from other causes of MCI by the presence of core clinical features of DLB and diagnostic biomarkers such as reduced dopamine transporter uptake in the basal ganglia as assessed using dopaminergic single‐photon emission computed tomography/positron emission tomography (SPECT/PET), reduced cardiac metaiodobenzylguanidine uptake on myocardial scintigraphy, and polysomnography‐diagnosed rapid eye movement (REM) sleep without atonia.10