FLUENcy-targeted cognitive Training after subthalamic Deep Brain Stimulation in Parkinson's Disease

INTERVENTION: Group 1: Participants with idiopathic Parkinson’s syndrome following bilateral subthalamic deep brain stimulation (STN‐DBS) who are randomized to the intervention group 3 months after surgery. Over a period of 3 months, participants complete digital, domain‐specific cognitive training, targeted on verbal fluency and executive functions. The training is conducted 2–3 times per week, 30 minutes each, and begins after the baseline assessment (T1; 3 months after STN‐DBS). The post‐intervention assessment takes place after completion of the 3‐month training phase (T2; 6 months after STN‐DBS). A follow‐up assessment takes place 12 months after the STN‐DBS. Group 2: Participants with idiopathic Parkinson’s syndrome who have undergone bilateral subthalamic deep brain stimulation (STN‐DBS) and who are randomized to the control group 3 months after surgery. During the intervention period, participants do not receive structured cognitive training and continue to receive their regular clinical care. The control group participates in standardized neuropsychological and clinical assessments at the scheduled time points. Upon completion of the 12‐month follow‐up (T3), participants are offered access to the digital cognitive training program. CONDITION: ; G20 Parkinson disease PRIMARY OUTCOME: Difference between the intervention and control groups in the change in verbal fluency from T1 (3 months after subthalamic deep brain stimulation, prior to the start of the intervention) to T2 (6 months after subthalamic deep brain stimulation, following completion of the 3‐month intervention), assessed using a composite score derived from phonemic and semantic verbal fluency performance on the Regensburger Verbal Fluency Test (RWT). SECONDARY OUTCOME: 1. Difference between the intervention and control groups in the change in global cognitive functioning and other cognitive domains (executive functions, visuocognition, memory, attention, and language) from T1 (3 months after STN‐DBS, prior to the start of the intervention) to T2 (6 months after STN‐DBS, following completion of the 3‐month intervention). ; ; 2. Difference between the intervention and control groups in the change in subjective cognitive complaints from T1 to T2. ; ; 3. Difference between the intervention and control groups in the change in health‐related quality of life from T1 to T2. ; ; 4. Differences between the intervention and control groups in changes in depressive symptoms, anxiety, sleep quality, fatigue, apathy, and other non‐motor and motor Parkinson’s disease‐related symptoms from T1 to T2. INCLUSION CRITERIA: ‐ Confirmed diagnosis of Parkinson’s disease based on routine clinical practice and in accordance with the diagnostic criteria of the Movement Disorder Society (MDS) ‐ 3 months post‐surgery following bilateral STN‐DBS ‐ Cognitive vulnerability, defined as the presence of at least one of the following criteria (3 months post‐surgery): 1. Mild cognitive impairment based on a global cognitive screening test (MoCA < 26) 2. Subjectively reported cognitive decline, assessed via MDS‐UPDRS Item 1.1 (score = 1) 3. Reduced verbal fluency, defined as an RWT z‐score = 1 on at least one RWT subtest ‐ Normal or adequately corrected vision and hearing ‐ German as a native language or sufficient proficiency in German to complete the test procedures ‐ Sufficient computer skills and access to a personal desktop computer or laptop with an internet connection