Table 2 Data set: assessment at presurgical/postsurgical baseline, visits 1–3

Motor assessments

• Movement Disorder Society-Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) III (medication-off/−on state)

• MDS-UPDRS I, IV

• Clinical Dyskinesia Rating Scale (CDRS)

Global cognitive function

• Alzheimer’s Disease Assessment Scale, cognitive subscale (ADAS-cog)

Activities of daily living

• Alzheimer’s Disease Cooperative Study, Activities of Daily Living (ADCS-ADL)

• MDS-UPDRS II

Neuropsychiatric symptoms

• Beck Depression Inventory (BDI) II,

• Starkstein Apathy Scale

• Neuropsychiatric inventory (NPI)

Domain specific (frontal executive) tests

• Delis-Kaplan Executive Function Systems (D-KEFS) verbal fluency battery

• Wisconsin Card Sorting Test (modified version)

• Trail Making Task (TMT) Part A + B

• Stroop Test (Victoria Version)

• Symbol Digit Modalities Test (SDMT)

Domain specific (attention) test

• Brief Test of Attention (BTA)

Quality of life

• Parkinson’s Disease Questionnaire (PDQ39)

• EuroQol (EQ)-5d

Health economics

• EQ-5d/quality-adjusted life years (QALYs)

Caregiver burden/quality of life

• Zarit Burden Interview (ZBI)

• Short form (SF)-36

Clinical global impression of change

• Baseline interview: Visit 1

• Follow-up: Visits 2 & 3