NCT02920632.

Methods	RCT (ongoing) of online cognitive training (COGTIPS ‐ COGnitive Training In Parkinson Study) vs online cognitive training of games that incorporate cognitive activities
Participants	Subjective cognitive complaints, measured by the Parkinson's Disease Cognitive Functional Rating Scale score > 3 (PD‐CFRS); a score above 3 indicates significant cognitive complaints that are milder than complaints associated with Parkinson's disease dementia. Questionnaire is filled in by the participant. Participants' Hoehn and Yahr stage is lower than 4 Access to a computer or tablet and willing to sign informed consent Exclusion criteria: indications for a dementia syndrome, measured by the self‐administered Gerocognitive Examination (score < 14) or the Montreal Cognitive Assessment (score < 22).
Interventions	8‐week training (COGTIPS) ‐ training contains several games that are designed to train cognitive functions; 3 times a week for 45 minutes Control group receives online gaming cognitive activities.
Outcomes	Primary outcome: executive function measured by the Tower of London Secondary outcomes: subjective cognitive complaints measured by the PD‐CFRS; executive function measured by the Stroop colour‐word task, the Letter fluency task, and the Tower of London; risk reduction of PD‐MCI/Parkinson's disease dementia (PDD) development at follow‐up Outcomes measured at 6 months, 1 year, and 2 years.
Notes	Although risk reduction of PD‐MCI/PDD development at follow‐up is an outcome for the study, participants may meet PD‐MCI criteria at baseline. Trial is ongoing.

RCT: Randomised Controlled Trial

PD: Parkinson's disease

PD‐MCI: Parkinson's Disease–Mild Cognitive Impairment

PDD: Parkinson's disease dementia