Cognitive outcome and reliable change indices two years following bilateral subthalamic nucleus deep brain stimulation

Abstract

Subthalamic nucleus deep brain stimulation (STN-DBS) is currently the treatment of choice for medication-resistant levodopa-related motor complications in patients with Parkinson’s disease (PD). While STN-DBS often results in meaningful motor improvements, consensus regarding long-term neuropsychological outcome continues to be debated. We assessed the cognitive outcomes of 19 STN-DBS patients compared to a group of 18 medically-managed PD patients on a comprehensive neuropsychological battery at baseline and two years post-surgery. Patients did not demonstrate changes in global cognitive functioning on screening measures. However, neuropsychological results revealed impairments in nonverbal recall, oral information processing speed, and lexical and semantic fluency in STN-DBS patients compared to PD controls 2 years post-surgery in these preliminary analyses. Additionally, reliable change indices revealed that approximately 50% of STN-DBS patients demonstrated significant declines in nonverbal memory and oral information processing speed compared to 25% to 30% of PD controls, and 26% of STN-DBS patients declined on lexical fluency compared to 11% of PD patients. Approximately 30% of both groups declined on semantic fluency. The number of STN-DBS patients who converted to dementia 2 years following surgery was not significantly different from the PD participants (32% versus 16%, respectively). Our results suggest that neuropsychological evaluations may identify possible mild cognitive changes following surgery.

Cognitive Effects of Subthalamic Nucleus Stimulation in Parkinson’s Disease: A Controlled Study

“…In both studies, surgical and control groups exhibited deterioration in verbal fluency and other variables related to executive functions at the 6-month follow-up, with the surgical groups showing a significantly greater worsening. Non-randomized controlled studies with a longer follow-up (1–3 years) also reported that verbal fluency is the main impaired neuropsychological variable after the procedure [9,10,11,12]. …”

Cognitive and Behavioural Changes After Deep Brain Stimulation of the Subthalamic Nucleus in Parkinson's Disease

“…Such comparative studies consistently found that performance on verbal fluency tasks was significantly better in Parkinsonian patients treated only by anti-Parkinsonian drugs, as compared to patients who underwent deep brain stimulation of the subthalamic nucleus and were followed-up for 6 months (Witt et al, 2008), 1 year (Castelli et al, 2010), 2 years (Williams et al 2011) and 3 years (Zangaglia et al, 2009). …”

“…Recently, some investigations have attempted to compare performance on verbal fluency tasks in two different groups of patients with Parkinson's disease, namely patients treated by deep brain stimulation of the subthalamic nucleus versus Parkinsonian patients treated only by anti-Parkinsonian drugs (Zangaglia et al, 2009;Castelli et al, 2010;Williams et al, 2011). Such comparative studies consistently found that performance on verbal fluency tasks was significantly better in Parkinsonian patients treated only by anti-Parkinsonian drugs, as compared to patients who underwent deep brain stimulation of the subthalamic nucleus and were followed-up for 6 months (Witt et al, 2008), 1 year (Castelli et al, 2010), 2 years (Williams et al 2011) and 3 years (Zangaglia et al, 2009).…”

“…However, in most studies which recruited a control group of medically-treated Parkinsonian patients the follow-up was relatively short, with follow-up periods of 6 months (Witt et al, 2008), 1 year (Castelli et al, 2010), 2 years (Williams et al, 2011) and 3 years (Zangaglia et al, 2009). Studies recruiting a control group of medically-treated Parkinsonian patients with a longer follow-up period are currently needed.…”

Neuropsychiatric Effects of Subthalamic Nucleus Deep Brain Stimulation in Parkinson Disease in China: A Prospectively Controlled Study

“…Up to now, it is widely acknowledged that STN-DBS does not impair overall cognition, although there is a selective decrease in certain cognitive domains. Some found unchanged global cognition, impairments in nonverbal recall, oral information processing speed, and verbal fluency in STN-DBS patients compared to PD controls 2 years after surgery [16]. One Japanese study found improvement in motor and anxiety apart from decline in abstract thinking and verbal fluency 1 month postsurgery in the medication-on and stimulationon condition.…”