SLC18A2 and Parkinson disease: A PET study in PD patients assessed vesicular monoamine transporter 2 (VMAT2) and cerebral glucose metabolism before DBS surgery and 4–6 months after STN-DBS and showed improvement of motor and neuropsychiatric symptoms while VMAT2 had decreased in the caudate and putamen along with decreased cerebral glucose metabolism in the striatum (Smith et al., 2019).