Baschi et al. (2019) found that in newly diagnosed Parkinson’s disease patients, motor disability (measured by H&Y stage, p < 0.01) and antidepressant use (p < 0.01) were significantly associated with MBI. Yoo et al. (2020) further discovered that a decrease in dopamine transporter availability in the anterior striatum (OR: 0.58, p = 0.008) was related to MBI motor deficits in Parkinson’s disease patients. The gene discussed is SLC6A3; the disease is Parkinson disease.