|Year : 2021 | Volume
| Issue : 5 | Page : 1511--1512
Exploring the Relationship between Bradykinesia and Cognitive Impairment in Parkinson's Disease
Sahil Mehta, Vivek Lal
Department of Neurology, PGIMER, Chandigarh, India
Prof. and Head, Department of Neurology, PGIMER, Chandigarh
|How to cite this article:|
Mehta S, Lal V. Exploring the Relationship between Bradykinesia and Cognitive Impairment in Parkinson's Disease.Neurol India 2021;69:1511-1512
|How to cite this URL:|
Mehta S, Lal V. Exploring the Relationship between Bradykinesia and Cognitive Impairment in Parkinson's Disease. Neurol India [serial online] 2021 [cited 2022 Jan 23 ];69:1511-1512
Available from: https://www.neurologyindia.com/text.asp?2021/69/5/1511/329573
Parkinson's disease (PD) is a common neurodegenerative disorder with motor as well as non-motor features. Cognitive dysfunction is an important non-motor symptom of Parkinson's disease which can occur throughout the course of the disease.
The study by Menon et al. in this issue of Neurology India in 70 patients of Parkinson's disease has attempted to explore the relationship between motor speed and cognitive performance. The authors have compared the neuropsychological profile between patients with and without deficits in motor speed as assessed by the Finger Tapping Test (FTT). There were significant differences with worse cognitive performance in executive functions, verbal recognition, visuospatial functions, visual learning and memory in the group with deficits in motor speed elicited by the FTT.
The incidence of dementia increases with the advancement of the disease with 90% of patients affected by ten years as shown by long term longitudinal studies. The cognitive impairment in Parkinson's disease can range from mild cognitive impairment to mild, moderate and severe PD dementia. It often involves executive function, attention, visuospatial function and working memory and results from the dysfunction of frontal subcortical circuitry. The underlying mechanisms for cognitive impairment include cortical Lewy body pathology, the involvement of cholinergic, noradrenergic and serotonergic systems, inflammation, mitochondrial dysfunction and genetic contribution.
Bradykinesia, a cardinal feature of Parkinson's disease is usually tested by the Finger tap test (FTT) to look for the decrement in speed and amplitude of the movement. FTT is a measure of fine motor speed and coordination and is also being increasingly utilized to detect cognitive decline in older adults. Tomita et al. studied 102 community dwelling older adults and developed a decision tree model using Montreal Cognitive Assessment (MoCA) visuospatial/executive function subscale, stride length and finger tap test. The authors found a sensitivity and specificity of 83.3% and 82.9% respectively to predict cognitive decline.
Rabinowitz et al. examined the association between spontaneous finger tapping and cognition in 170 elderly patients and found a significant inverse correlation between the length and variability of the finger touch phase with the measures of attention and short-term memory.
As far as Parkinson's disease is concerned, it is well known that the postural instability gait difficulty (PIGD) subtype has a highly increased risk of subsequent dementia compared to tremor dominant (TD) phenotype. Arie et al. in their 5-year prospective study on 63 PD patients, demonstrated worse cognitive scores particularly related to executive function in patients with PIGD motor subtype compared to TD subtype.
Schneider et al. in their study of 94 PD patients also found a negative association of bradykinesia with executive dysfunction, visuospatial learning and memory deficits and set-shifting abnormalities measured by standard neuropsychological testing further strengthening the association between cognitive performance and motor speed.
The relationship between finger tapping and executive functions has also been demonstrated with the help of functional imaging techniques. Functional MRI studies have implicated activation of dorsolateral prefrontal cortex in both finger tapping and digit span testing.
To summarize, the finger tap test not only measures bradykinesia but also attention and working memory. As correctly highlighted by the authors of this cross-sectional study, there is no doubt “Motor speed” matters! The research will pave the way in judicious planning of larger cohorts of patients with PD to further explore the intricate relationship of a simple test like the FTT and various cognitive domains.
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