Cognitive Dysfunction In Parkinson's

Inclusion Criteria

• We will recruit 60 PD patients through the University Colorado Hospital (UCH) Movement Disorders Clinic diagnosed with probable PD using United Kingdom (UK) Brain Bank Criteria.
• PD patients will be of mild to moderate severity based on the Hohn and Yahr scale (score of 3 or less in on medication state) and be on a stable dose of PD medications.
• Clinical severity will also be assessed using the Unified Parkinson Disease Rating Scale.
• We do not anticipate recruitment to be difficult as UCH Movement clinics see over 800 PD patients annually, the majority of whom are stage 3 or less.
• Controls will be approximately matched for age and gender as a group and recruited through clinic (spouses) and advertisements in the community.

Exclusion Criteria

• Subjects will be excluded if they have significant depression (Beck Depression Inventory33 > 14)
• Dementia (Mini Mental State Examination34 < 26 or Frontal Assessment Battery35 < 14)
• Other neurological or psychiatric illness
• Significant history of head injury, significant systemic medical diseases (e.g. liver failure, kidney failure, poorly controlled diabetes)
• Deep Brain Stimulation (DBS)
• Cognitive enhancing medications (e.g. stimulants or acetylcholinesterase inhibitors) or contraindications to either TMS or MRI (pregnancy, pacemaker, unstable cardiac disease, skull lesion, claustrophobia, history of epilepsy or on medications known to lower seizure threshold).