Upper limb movements in dementia with Lewy body: a quantitative analysis

Dementia with Lewy body is a neurodegenerative disorder affecting both cognitive and motor domains. Motor impairment manifests predominantly as a symmetrical/mild asymmetrical parkinsonian syndrome that is only mildly responsive to Levodopa. To characterize motor dysfunction in dementia with Lewy body, we quantitatively assessed upper limb movements using a motion-capture system. Ten patients and ten healthy controls were tested while performing the hand-to-mouth movement of which speed, smoothness and accuracy features were measured. The results showed that individuals with dementia with Lewy body required a longer time to complete the task, particularly due to a prolonged duration of the adjusting phase (i.e., when approaching the target/mouth). The overall motor performance of dementia with Lewy body patients closely resembled what previously observed in patients affected by both Parkinson's disease and ataxia while performing the same task. Moreover, the severity of parkinsonian symptoms as assessed by the UPDRS-III scale impacted on the velocity of movement alone whereas impairment of executive functions correlated with variables related to the phase of targeting the mouth. This study provides new information about upper limb motor dysfunction in dementia with Lewy body.