On their own, MAO-B inhibitors can slow the rate of PD symptom progression and extend survival via neuroprotection and/or symptom relief; MAO-B inhibitors have been shown to ameliorate motor symptoms and improve motor fluctuation in both early and advanced stages of PD, and they may also help attenuate mood deflection, cognitive impairment, sleep disturbances, and fatigue [87,88]. The gene discussed is MAOB; the disease is Cognitive impairment.