SLC6A3 and Alzheimer disease: Dopamine transporter (DAT) single-photon emission computed tomography (SPECT) is an imaging modality that can effectively differentiate neurodegenerative parkinsonian syndromes (PS), including Parkinson’s disease (PD) and dementia with Lewy bodies (DLB) from other neurological disorders not characterized by dopaminergic degeneration, such as Alzheimer disease, drug-induced Parkinsonism, and essential tremor [1, 2].