The association between dexterity and cognitive functioning in healthy elderly: A kinematic analysis

Abstract

Aging has a degenerative effect on hand function and cognition. After the age of 65, most healthy elders experience sensorimotor changes and cognitive declines of various kinds which can make activities of everyday life a challenge. To our knowledge, few studies have investigated the possible interplay between cognitive function and dexterity in the elderly. The purpose of the present study was to assess age-related differences in hand dexterity with the use of kinematic measures on performance of the Purdue Pegboard test. Also, we wanted to evaluate whether executive functions and attention would be associated to the kinematic outcomes in dexterity tasks among elderly adults. Fifteen elderly and fifteen younger adults participated in the study. All participants were tested with a battery of cognitive tests including: Digits Span (Forwards and Backwards), the Stroop test, MMSE, Trail Making Test, BDI, Hand Dynamometer and the Handedness Inventory. Two subtests of the Purdue Pegboard were used to evaluate dexterity. Performance on these two tests was analyzed with a motion capture system (Vicon Motus System) in order to obtain kinematic measurements. The employed kinematic parameters were angular displacement and angular velocities of the angle located between the thumb and index finger of the right hand. Results showed that healthy elderly subjects were slower on dexterity tasks and less performing in the majority of the cognitive tests than younger adults. Correlational analyses for the elderly group showed that tasks measuring attentional mechanisms and executive functioning were significantly associated to kinematic parameters on the easiest dexterity task. While for a more complex dexterity task, the older group showed significant correlations between kinematic parameters and tests of psychomotor control and general mental status. The elderly subjects' performance were slower and presented less variability in movements to complete the dexterity tasks than younger participants. These results tells us that elders execute slower the same dexterity task as compared to younger adults with different movement patters, and the age-related declines in cognitive domains can to a certain degree explain these findings.