All patients were assessed before the procedure and at one year after surgery; 40 patients were further followed up until the 5-year mark.
Long-term impact of subthalamic stimulation on cognitive function in patients with advanced Parkinson's disease
 
  Keywords
 
 
  
   Cognitive impairment
  
 
 
  
   Deep brain stimulation
  
 
 
  
   Depression
  
 
 
  
   Parkinson's disease
  
 
 
  
   Quality of life
  
 
 
  
   Subthalamic nucleus
  
 
Objective
The aim of this study was to evaluate the effects of deep brain stimulation of the subthalamic nucleus (DBS-SN) on cognitive function in patients with Parkinson's disease (PD) 5 years after surgery.
Material and methods
We conducted a prospective study including 50 patients with PD who underwent DBS-SN (62.5% were men; mean age of 62.2±8.2 years; mean progression time of 14.1±6.3 years). 
All patients were assessed before the procedure and at one year after surgery; 40 patients were further followed up until the 5-year mark. 
Follow-up assessments included the following neuropsychological tests: Mini–Mental State Examination (MMSE), Mattis Dementia Rating Scale (MDRS), letter-number sequencing of the WAIS-III (WAIS-III-LN), clock-drawing test, Rey auditory verbal learning test (RAVLT), Benton Visual Retention Test (BVRT), Judgment of Line Orientation (JLO) test, FAS Phonemic Verbal Fluency Test, Stroop test, and the Montgomery-Asberg Depression Rating Scale (MADRS).
Results
Patients were found to score lower on the MMSE (−0.89%), clock-drawing test (−2.61%), MDRS (−1.72%), and especially phonemic (−13.28%) and sematic verbal fluency tests (−12.40%) at one year after surgery. 
Delayed recall on the RAVLT worsened one year after the procedure (−10.12%). 
At 5 years, impairment affected mainly verbal fluency; scores decreased an additional 16.10% and 16.60% in semantic and phonemic verbal fluency, respectively. 
Moderate decreases were observed in immediate recall (−16.87%), WAIS-III-LN (−16.67%), and JLO test (−11.56%).
Discussion
In our sample, DBS-SN did <scp><neg>not</neg> result in <dis>global cognitive impairment</dis> 5 years after surgery</scp>. 
<dis>Verbal function was found to be significantly impaired</dis> one year after the procedure. 
<dis>Impaired learning and visuospatial function</dis> may be attributed to degeneration associated with PD.
Objective
The aim of this study was to evaluate the effects of deep brain stimulation of the subthalamic nucleus (DBS-SN) on cognitive function in patients with Parkinson's disease (PD) 5 years after surgery.
Material and methods
We conducted a prospective study including 50 patients with PD who underwent DBS-SN (62.5% were men; mean age of 62.2±8.2 years; mean progression time of 14.1±6.3 years). 
All patients were assessed before the procedure and at one year after surgery; 40 patients were further followed up until the 5-year mark. 
Follow-up assessments included the following neuropsychological tests: Mini–Mental State Examination (MMSE), Mattis Dementia Rating Scale (MDRS), letter-number sequencing of the WAIS-III (WAIS-III-LN), clock-drawing test, Rey auditory verbal learning test (RAVLT), Benton Visual Retention Test (BVRT), Judgment of Line Orientation (JLO) test, FAS Phonemic Verbal Fluency Test, Stroop test, and the Montgomery-Asberg Depression Rating Scale (MADRS).
Results
Patients were found to score lower on the MMSE (−0.89%), clock-drawing test (−2.61%), MDRS (−1.72%), and especially phonemic (−13.28%) and sematic verbal fluency tests (−12.40%) at one year after surgery. 
Delayed recall on the RAVLT worsened one year after the procedure (−10.12%). 
At 5 years, impairment affected mainly verbal fluency; scores decreased an additional 16.10% and 16.60% in semantic and phonemic verbal fluency, respectively. 
Moderate decreases were observed in immediate recall (−16.87%), WAIS-III-LN (−16.67%), and JLO test (−11.56%).
Discussion
In our sample, DBS-SN did not result in global cognitive impairment 5 years after surgery. 
Verbal function was found to be significantly impaired one year after the procedure. 
Impaired learning and visuospatial function may be attributed to degeneration associated with PD.
All patients were assessed before the procedure and at one year after surgery; 40 patients were further followed up until the 5-year mark.