Objective: Longterm, “real-life” assessment of cognitive evolution following subthalamic (STN) deep brain stimulation (DBS) in patients suffering from Parkinson´s disease.

Background: Anecdotal reports have speculated STN-DBS to be associated with aggravated cognitive decline in PD patients with mild cognitive deficits or dementia.

Methods: The present study includes all patients suffering from Parkinson´s disease, who were treated via continuous bilateral subthalamic DBS between 1997 and 2006 in Berlin, Charité University Hospital (n=104). Preoperative neuropsychological results were available in 79/104 of the patients. Thirty-seven/79 of these patients were additionally assessed after 6.3 ± 2.2 years (range 3.6-10.5 ys.) post surgery via neuropsychological and motor test batteries. In the other 42 patients follow-up assessment were not feasible due to death (n=21), loss of patient contact (n=9) or patients refusal of retesting (n= 12). Cognitive conditions were classified as no or mild cognitive impairment or dementia according to Litvan et al., (2012, MovDis 27: 349-56).

Results: DBS-treated patients, available for longterm follow-up (n=37; mean age 67.6 ± 6.9 ys.), showed no (24.3%; 9/37;) or mild preoperative cognitive impairment (75.7%; 25/37) following mean disease duration of 11.3 ± 4.1 ys at DBS-surgery. Postoperatively (mean disease duration at last follow-up: 17.1 ± 5.1 years), 19% (7/37) had no cognitive impairment, while approximately 41% (15/37) presented with either mild cognitive impairment or dementia (15/37). Overall, STN-DBS-treated patients deteriorated by 1.6/140 points/year (1.1%) in the Mattis dementia rating scale (MDRS). Disease duration, but not age, at DBS-surgery positively correlated with postoperative cognitive decline measured by MDRS (r = 0.4; p = 0.02).

Conclusions: This observational, “real-life” study provides long term results of cognitive decline in STN-DBS-treated patients. Obviously, a major limitation of this study is the absence of a control group (i.e. no DBS). However, preliminary comparison of the present data with medically treated patients with Parkinson´s disease in other studies (Hely et al., Mov Disord 23: 837-44) do not support a disease-modifying effect of STN-DBS on cognitive domains. Our data did not confirm age at DBS as a major determinant for postoperative cognittive decline.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/longterm-outcome-of-cognition-following-subthalamic-deep-brain-stimulation-in-parkinsons-disease/