Affiliations: [a] Department of Sport and Health Sciences, Technical University of Munich, Munich, Germany
| [b] Schön Klinik Bad Aibling, Bad Aibling, Germany
| [c] Department of Neurology, Cantonal Hospital of St. Gallen, St. Gallen, Switzerland
| [d] Department of Psychiatry and Psychotherapy, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
Correspondence:
[*]
Correspondence to: Prof. Dr. Joachim Hermsdörfer, Technische Universität München (TUM), Lehrstuhl für Bewegungswissenschaften, Georg-Brauchle-Ring 62, 80992 München, Germany. Tel.: +49 89 289 24550; E-mail: joachim.hermsdoerfer@tum.de.
Note: [1] These authors contributed equally to this work.
Abstract: Background:Alzheimer’s disease (AD) affects several cognitive functions and causes altered motor function. Fine motor deficits during object manipulation are evident in other neurological conditions, but have not been assessed in dementia patients yet. Objective:Investigate reactive and anticipatory grip force control in response to unexpected and expected load force perturbation in AD. Methods:Reactive and anticipatory grip force was investigated using a grip-device with force sensors. In this pilot study, fifteen AD patients and fourteen healthy controls performed a catching task. They held the device with one hand while a sandbag was dropped into an attached receptacle either by the experimenter or by the participant. Results:In contrast to studies of other neurological conditions, the majority of AD patients exerted lower static grip force levels than controls. Interestingly, patients who were slow in the Luria’s three-step test produced normal grip forces. The timing and magnitude of reactive grip force control were largely preserved in patients. In contrast, timing and extent of anticipatory grip forces were impaired in patients, although anticipatory control was generally preserved. These deficits were correlated with decreasing Mini-Mental State Examination scores. Apraxia scores, assessed by pantomime of tool-use, did not correlate with performance in the catching task. Conclusion:We interpreted the decreased grip force in AD in the context of loss of strength and lethargy, typical for patients with AD. The lower static grip force during object manipulation may emerge as a potential biomarker for early stages of AD, but more studies with larger sample sizes are necessary.
Keywords: Alzheimer’s disease, dementia, early diagnosis, fine motor control, hand strength
