Deep Brain Stimulation for Treatment of Parkinson’s Disease: Benefits and Neuropsychological Outcomes

              Parkinson’s Disease is a life-debilitating motor-neuron disease that afflicts nearly sixty-thousand Americans [as of 2020]. It impedes everyday life and causes symptoms such as “brain freezes… muscle spasms and struggling to talk,” as shared by Bill Ragle, a finance professor at Cedarville University with Parkinson’s Disease (Johnson, Professor with Parkinson’s Disease Makes a Comeback). Currently, there are no cures for Parkinson’s Disease but current research involving deep brain stimulation has shown to help slow its onset. Bill Ragle is one of the new patients for this new technology. In treatment of Parkinson’s, Deep Brain Stimulation aids in reducing involuntary movements, prevents struggling with speech, and improves ability to walk. Although impressive, researchers are still investigating potential risks, such as neuropsychological effects. 

             In the research article “Neuropsychological outcomes from constant current deep brain stimulation for Parkinson’s Disease,” researchers compared neuropsychological effects of deep brain stimulation to electrode placement alone. One hundred-thirty-six patients with Parkinson’s Disease were evaluated after undergoing bilateral subthalamic device implant surgery. Patients were randomly assigned between three groups: 1. Stimulation immediately post-surgery 2. Stimulation beginning three months post-surgery 3. Control Group. Stimulation in this experiment defines the activation of the implantation devices. Three neuropsychological tests were given pre-surgery, three months post, and one-year post to assess the neurobehavioral safety of this treatment. Before surgery, all patients underwent an initial neuropsychological evaluation, no later than one week prior to the day of surgery. These initial evaluations were used as reference points to indicate that all patients did not have an already-existing cognitive impairment or depression before receiving the implants. The tests observed “overall level of cognitive function, attention and working memory, verbal fluency [tests], depression, and measures of intelligence… Wechsler Abbreviated Scale of Intelligence [WASI] and the Boston Naming Test were administered at baseline to facilitate dementia screening” (Troster, et al., Neuropsychological outcomes from constant current deep brain stimulation for Parkinson’s Disease). 

             Within-groups t-tests showed a degradation in verbal fluency; the experimental group also displayed increased levels of delayed story-recall. Despite this, overall statistical analyses of the data indicate that there is no significant difference between neuropsychological test scores, as compared to the baseline [score]. These research findings agreed with the already-existing research on this topic—that deep-brain stimulation does not negatively impact cognitive abilities. Although both groups showed depreciated verbal fluency skills, the experimental groups had a more sever effect. Such micro-cognitive impairments may be corrected with brain stimulation to other areas; further research is necessary. Additionally, further research is needed to investigate whether baseline neuropsychological-, patient-, and disease-related variables considered in tandem… [may be able to] predict the risk of overall cognitive decline” in patients (Troster, et al.). Both topics are worth-looking into, as these may be able to improve deep brain stimulation devices. 

            This experiment reveals the neurobehavioral safety of deep brain stimulation as a form of treatment in patients with Parkinson’s Disease. The constant, bilateral current had little overall impact in cognitive performance, with only slight [negative] changes in verbal fluency. This form of treatment is currently the best in treating Parkinson’s patients’ motor symptoms, as well as the best alleviator of Parkinson’s medication [long-term-use of levodopa] side effects, such as dyskinesia. This study also revealed the potential for decline in cognitive-performance, mainly verbal fluency but also memory, attention and executive functioning. These side effects may affect between twenty-five to fifty percent of patients with deep brain stimulating implantation devices. Regardless, the high-level of improvement in motor functioning and control in Parkinson’s patients leaves little worry about [potential] these micro-effects. These implantation devices to stop “involuntary movements, struggles with talking and walking,” as Bill Ragle has experienced, are very exciting in the ever-expanding Parkinson’s research field (Johnson). 

           This newly developing form of treatment allows doctors of neuromuscular disease patients to “control the shape, range, direction and position of electrical lead stimulation,” providing more precise care (Fortune Business Insights). Deep brain stimulation implantation devices are becoming a more desirable form of treatment, due to its personalized style, as well as its impressive success in alleviating symptoms, such as those experienced by people with Parkinson’s. This study’s findings were congruent with previous research on such devices and concluded that they do not pose cognitive impairments, though they may cause some cognitive slowing. The many potential uses of such devices leaves much room for excitation in the neuroscience field, indicating further studies should be conducted. 

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