Mental slowness in patients with Parkinson’s disease: Associations with cognitive functions?

Abstract

Introduction: Motor slowness (bradykinesia) is a core feature of Parkinson's disease (PD). It is often assumed that patients show mental slowness (bradyphrenia) as well; however, evidence for this is debated. The aims of this study were to determine whether PD patients show mental slowness apart from motor slowness and, if this is the case, to what extent this affects their performance on neuropsychological tests of attention, memory, and executive functions (EF). Method: Fifty-five nondemented PD patients and 65 healthy controls were assessed with a simple information-processing task in which reaction and motor times could be separated. In addition, all patients and a second control group (N = 138) were assessed with neuropsychological tests of attention, memory, and EF. Results: While PD patients showed significantly longer reaction times than healthy controls, their motor times were not significantly longer. Reaction and motor times were only moderately correlated and were not related to clinical measures of disease severity. PD patients performed significantly worse on tests of attention and EF, and for the majority of neuropsychological tests 11-51% of the patients showed a clinically impaired performance. Reaction times did not, however, predict patients' test performance, while motor times were found to have a significant negative influence on tests of attention. Conclusions: PD patients show mental slowness, which can be separated from motor slowness. Neuropsychological test performance is not influenced by mental slowness; however, motor slowness can have a negative impact. When interpreting neuropsychological test performance of PD patients in clinical practice, motor slowness needs to be taken into account.

Computational Modeling for Neuropsychological Assessment of Bradyphrenia in Parkinson’s Disease

“…The present data show how the construct of PD-related bradyphrenia [15][16][17][18][19][20][21][22][23], which is difficult to study with purely behavioral methods, can be investigated through applying computational techniques. Computational modeling of trial-by-trial reinforcement learning on the WCST [44] revealed that PD patients and HC participants learned similarly from trial-by-trial feedback on the cWCST.…”

“…We conclude from our data that PD patients are characterized by a reduced flexibility of cognitive learning compared to HC participants (see Figure 4a,b for illustration). Thus, PD pathophysiology [2][3][4] is associated with a cognitive symptom, which can probably be best described as 'inflexibility of thought' (i.e., bradyphrenia; [19][20][21][22]). As a result, PD should not merely be considered as a 'movement disorder' because cognitive symptoms such as attentional inflexibility represent an integral manifestation of the disease around its mid-stage [2][3][4].…”

“…A cardinal motor symptom of many PD patients is bradykinesia, which might be best summarized as 'slowness of movement' [13,14]. The neuropsychological equivalent of bradykinesia in PD is bradyphrenia, i.e., 'slowness of thought' [15][16][17][18][19][20][21][22]. However, bradyphrenia is not synonymous with slowed behavioral indicators of processing speed (e.g., response times in laboratory tasks), which would necessarily originate from both bradyphrenia and bradykinesia.…”

A Proposed Circuit Computation in Basal Ganglia: History‐Dependent Gain

“…Bradyphrenia (slowness of thought) can be dissociated from bradykinesia in tasks with distinct cognitive and motor aspects. [91][92][93] Like bradykinesia, bradyphrenia has been shown to be mediated by dopamine. 94 We conjecture that bradyphrenia might be similarly explained by reduced gain on a cognitive process.…”

What are the Acute Effects of Aerobic Exercise on Fractionated Response Time: A Systematic Review and Meta-analysis

“…Using FRT instead of RT provides a more precise estimate of the location of the effect of aerobic exercise on cognitive or motor components of the response. In addition, FRT may led to a better understanding of the presence of cognitive or motor deficits in different pathological conditions [18,59,60]. For example, in a recent study on Parkinson's disease patients, the authors found the disease mainly affected the speed of mental processing (PMT) without any significant change in motor execution of the task (MT) [59].…”