Is finger tapping a biomarker to classify cognitive status in octogenarian

Kutz, DF.; Fröhlich, S.; Rudisch, J.; Müller, K.; Voelcker-Rehage, C.

Zusammenfassung

Introduction: As societies age, more and more people are developing dementia. It has been shown that e.g. Alzheimer patients and cognitively healthy individuals differ in the performance of movement tasks (e.g. finger tapping). This study examined the relationship between finger tapping and cognitive function and the possibility of using finger tapping parameters (e.g. tap cycle, tap duration) to predict cognitive state. The results are discussed in terms of the diadochokinetic nature of finger tapping as associated with the age-related degeneration of cortical and subcortical motor areas (e.g. cerebellum). Methods: Finger tapping (recorded by a force transducer) was assessed in a group of 225 elderly participants (116 males; age 79–92 years; M = 82.5; SD = 2.4) in two conditions: self-selected pace and fast pace. Based on cognitive assessments, including the MoCA and CERAD-NP test battery, participants were classified as cognitively healthy individuals (CHI), participants with mild cognitive impairments (MCI), and those with possible MCI (pMCI). Results: Significant differences between groups, sex and a group × sex interaction in four parameters for the self-selected pace condition and eight parameters for the fast pace condition were shown. These parameters were used for classification by means of linear discriminant analysis (LDA). The first LDA component showed significant differences between CHI and pMCI and between CHI and MCI. Furthermore, the second LDA component showed significant differences between CHI and pMCI as well as between pMCI and MCI. Yet, the algorithm correctly classified only 50% of participants, regardless of group. Conclusion: It is shown that finger tapping parameters are of limited use in classifying cognitive status. Due to the diadochokinetic nature of the task, degeneration of the cerebellum may be the cause. Therefore, it is hypothesized that misclassified participants in the CHI group had more pronounced degeneration of the motor cerebellum than correctly classified participants. Thus, correctly classified CHI participants showed a faster tapping rhythm with a shorter tapping duration in the self-selected condition. Overall, when investigating whether cognitive state can be assessed based on simple finger movements, one must also consider the possible degeneration of relevant motor systems (e.g., the cerebellum). To establish tapping as a good classifier, researchers need to conduct additional motor tests to specifically determine the degeneration of the aforementioned areas.