An 85-year-old woman visited our hospital with repetitive diarrhea, nausea, and anorexia, as well as aggressive behavior. The neurologist decided to perform dopamine transporter imaging (F-FP-CIT PET/CT) for accurate diagnosis, taking into account the potential adverse effects of L-dopa that the patient had been taking for a long time. The uptake of dopamine transporter in the bilateral basal ganglia was well preserved, but reduced uptake in the left parotid gland was incidentally detected. A subsequent salivary scan showed reduced uptake in the left parotid gland with the same pattern as that on F-FP-CIT PET/CT.