SLC6A3 and Cognitive impairment: BMI, body mass index; COMT, catechol-O-methyl transferase; DA, dopamine agonist; DAT, device-aided therapy; DBS, deep brain stimulation; H&Y, Hoehn&Yahr; LCIG, levodopa-carbidopa infusion gel; LECGI, levodopa-entacapone-carbidopa infusion gel; LEDD, levodopa equivalent daily dose; MAO, monoamine oxidase; MCI, mild cognitive impairment; UPDRS, Unified Parkinson’s Disease Rating Scale.