Single-photon emission computed tomography (SPECT) with the dopamine transporter (DAT) ligand N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-I-123-iodophenyl)nortropane ([123I]FP-CIT) is widely used for the detection (or exclusion) of nigrostriatal degeneration in patients with a clinically uncertain Parkinsonian syndrome or suspected dementia with Lewy bodies [1–5]. This evidence concerns the gene SLC6A3 and dementia.