Evaluating the Effect of Mirtazapine on Anxiety in Parkinson's Disease Patients

Inclusion Criteria: * Men and women over 17 years old * Patient with Parkinson's disease according to UKPDSBB criteria * Patient with mild/moderate Parkinson's disease according to Hoehn and Yahr Scale (HY score = 1-3) * Self-report or clinical diagnosis of anxiety * Patients who have signed informed consent to participate in the study. Exclusion Criteria: * Pregnant and lactating women * Parkinson's patients with onset of disease in less than 1 year * Unstable medication for Parkinson's disease during the last two weeks * Parkinson's patients with DBS * Patients with other neurodegenerative diseases like multiple system atrophy (MSA), Huntington's and etc. * Patients with major depressive disorder * A history of using SSRIs, SNRIs, benzodiazepines and β-blockers during the last 4 weeks * A history of using MAO inhibitors * A history of alcohol and substance abuse * A history of acute stress during the last 3 months * A history of suicide * A history of cardiovascular diseases * A history of liver and or kidney disorders