Chronic deep brain stimulation of the subthalamic nucleus for Parkinson's disease: effects on cognition, mood, anxiety and personality traits.

Department of Neuroscience, University of Turin, Italy.
European Neurology (Impact Factor: 1.5). 02/2006; 55(3):136-44. DOI: 10.1159/000093213
Source: PubMed

ABSTRACT To evaluate modifications occurring in cognitive functions and behavioural aspects in a group of 72 consecutive patients with Parkinson's disease (PD) 15 months after bilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN).
72 consecutive PD patients bilaterally implanted for DBS of the STN were evaluated before and after surgery with a mean follow-up of 15 months. A neuropsychological assessment was performed to evaluate reasoning (Raven Colour Matrices), memory (Bisyllabic Word Repetition Test, Corsi's Block-Tapping Test, Paired-Associate Learning) and frontal executive functions (Trail Making Test Part B, Nelson Modified Card Sorting Test, phonemic and category verbal fluency tasks). Mood and suicidal ideation were evaluated using the Beck Depression Inventory (BDI). Anxiety was measured by means of the State-Trait Anxiety Inventory and personality traits were evaluated with the Structured Clinical Interview for the DSM-III-R Axis II Disorders (SCID-II). Assessment of thought disorders and apathy was based on subitems of the Unified Parkinson's Disease Rating Scale.
The comparisons between pre- and postoperative neuropsychological test scores showed a significant worsening only in phonemic and semantic verbal fluency tasks, while fewer errors were found in the Nelson Modified Card Sorting Test. Globally, behavioural assessment evidenced a small improvement in mood, as assessed by the BDI, in obsessive-compulsive and paranoid personality traits (SCID-II). Thought disorders worsened while suicidal ideation, anxiety and apathy showed no postoperative modifications. The analysis of individual outcomes (+/-1 SD criterion) evidenced a relevant postoperative cognitive decline in 3 patients out of 65 (4.5%). Moreover, following implantation, 1 patients exhibited psychosis (1.5%), 2 patients experienced a clinically relevant worsening of depressive symptoms (3%), 7 patients showed an increase in anxiety (12%) and 3 patients a worsening in depression and anxiety symptoms (3%). On the contrary, 12 patients (20%) showed a relevant improvement in mood and 14 patients (23%) a relevant reduction of anxiety symptoms after the surgery.
The present study confirms that STN DBS is cognitively safe since the only relevant change observed was a mild decrease in verbal fluency tasks. Globally, a small postoperative improvement was found in the BDI, and in two SCID-II subscales concerning obsessive-compulsive and paranoid personality traits, even though postoperative behavioural disturbances can occur in individual patients.

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    ABSTRACT: Putative changes of cognition after deep brain stimulation (DBS) in patients with Parkinson's disease (PD) are a matter of debate. The aim of this study was to assess cognitive abilities before and following bilateral subthalamic nucleus (STN) DBS and to review the available literature. Twenty patients underwent bilateral DBS of the STN. Cognitive skills were assessed in a standardized fashion before and at least at 12 months after the surgical intervention. There was a significant decline of both semantic and phonematic verbal fluency and a mild trend for a deterioration of verbal memory after DBS. Mood, general cognitive screening, and visospatial abilities remained unchanged. STN DBS in the treatment of PD has resulted in a significant reduction of motor symptoms and improved independence and quality of life in appropriately selected patients. However, it may have isolatable effects on verbal fluency and related function. Case series in the literature reported similar findings. Potential candidates for DBS should be counseled about the risk of mild cognitive declines.
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    ABSTRACT: Deep brain stimulation (DBS) is an effective technique for treating Parkinson's disease (PD) in the middle and advanced stages. The subthalamic nucleus (STN) is the most common target for clinical treatment using DBS. While STN-DBS can significantly improve motor symptoms in PD patients, adverse cognitive effects have also been reported. The specific effects of STN-DBS on cognitive function and the related mechanisms remain unclear. Thus, it is imperative to identify the influence of STN-DBS on cognition and investigate the potential mechanisms to provide a clearer view of the various cognitive sequelae in PD patients. For this review, a literature search was performed using the following inclusion criteria: (1) at least 10 patients followed for a mean of at least 6 months after surgery since the year 2006; (2) pre- and postoperative cognitive data using at least one standardized neuropsychological scale; and (3) adequate reporting of study results using means and standard deviations. Of ∼170 clinical studies identified, 25 cohort studies (including 15 self-controlled studies, nine intergroup controlled studies, and one multi-center, randomized control experiment) and one metaanalysis were eligible for inclusion. The results suggest that the precise mechanism of the changes in cognitive function after STN-DBS remains obscure, but STN-DBS certainly has effects on cognition. In particular, a progressive decrease in verbal fluency after STN-DBS is consistently reported and although executive function is unchanged in the intermediate stage postoperatively, it tends to decline in the early and later stages. However, these changes do not affect the improvements in quality of life. STN-DBS seems to be safe with respect to cognitive effects in carefully-selected patients during a follow-up period from 6 months to 9 years.
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May 20, 2014