Objective: We aimed to determine the predictors of cognitive decline and mood disorders after STN-DBS in PD.

Background: Cognitive impairment and mood disorders are the most common complications after subthalamic nucleus stimulation (STN-DBS) surgery. These symptoms may be related to a reduction in the levodopa dosage or caused by the DBS itself. The STN DBS effects on cognition and mood, including depression and anxiety, are mediated by alteration activity in mesocortical and mesolimbic pathways, as well as between cortical areas and the basal ganglia.

Method: A total of 22 PDpatients aged 45-60 years were examined. MRI voxel-based morphometry and tractography was applied before surgery. Neuropsychological testing was performed to identify 1) anxiety (Montgomery-Åsberg Depression Rating Scale and depression severity (Generalised anxiety disorder assessment GAD-7), 2) frontal-striatal, posterior cortical, and mixed subtypes of mild cognitive impairment (MCI) preoperatively and over the next 3–5 years after STN-DBS surgery in PD patients. Neuroimaging included MRI voxel-based morphometry and tractography.

Results: Within 3-5 years after STN-DBS surgery, 13 patients developed moderate or severe depression, and 12 progressed to severe anxiety. These patients had a more pronounced decrease in volume in the amygdala, hippocampus, orbitofrontal cortex, anterior cingulate and dorsolateral prefrontal cortex. In addition, PD patients with depression and anxiety progression showed a significant reduction in tract density connecting the amygdala with the lateral orbitofrontal cortex and dorsolateral prefrontal cortex.

In a retrospective analysis, PD patients with pre-surgical frontostriatal or mixed MCI had greater cognitive decline in subsequent years compared with the patients with posterior cortical MCI. These patients, along with a decrease in the density of the tracts connecting the frontal cortex with the caudate nucleus and putamen, had a more pronounced decrease in the volume of the orbitofrontal, ventromedial prefrontal cortex and hippocampus.

Conclusion: It is important to be able to predict which patients are most likely to develop emotional and cognitive impairment after STN-DBS surgery. To select candidates for STN-DBS surgery, it is necessary to take into account MRI morphometry and tractography data, as well as MCI subtypes prior to surgery.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/predictors-of-cognitive-impairments-and-mood-disorders-after-subthalamic-deep-brain-stimulation-in-patients-with-parkinsons-disease/