Increased age leads to decreased dexterity: is it really that simple?

It is commonly believed that with increased age, movement dexterity becomes slower and increasingly clumsy when performing simple every day tasks. In the General Introduction of this PhD thesis (Chapter 1), literature that supports evidence for this relationship was reviewed. In addition, literature that has attempted to understand co-variance factors that may influence the age and dexterity relationship were also presented. From this, the general thesis hypothesis raised was that other factors such as sense of touch, attention ability or strength might also correlate with age and so possibly could also explain the reduced dexterity variable. Five empirical chapters present the experiments conducted to address the hypothesis, and the data from these are discussed in the General Discussion (Chapter 7). The empirical chapters consisted of three main areas of experimentation. That is, Chapter 2 ran preliminary screening data, Chapters 3 and 4 tested the effects of selective attention ability on the age - dexterity relationship and Chapters 5 and 6 tested the effects of strength on the age - dexterity relationship. In more detail, Chapter 2 used standard clinical measurements to assess the effects of age on fine and gross movement dexterity, sense of touch, selective attention and strength. The data showed that all factors declined with increased age, but that strength and selective attention seemed particular relevant to general upper limb dexterity. In Chapter 3, the impact of selective attention ability was assessed using a modified and motion tracked dexterity task. This demonstrated that the age and dexterity relationship was not generalised across all movements, but instead was specific for phases of action that contained a selective attention component. Chapter 4 followed up these data by showing evidence of impaired selective attention and inhibition with increased age. Chapter 5 sought to clarify the impact that strength had on the age and dexterity relationship. The findings showed that while age and strength were related, age explained more of thedata’s variance for steadiness and movement tracking dexterity, whereas strength explained more of the data’s variance for aiming and tapping dexterity. In Chapter 6, the findings of Chapter 5 were tested by directly manipulating hand grip strength and measuring the resultant effects on tapping dexterity. The data supported Chapter 5 and confirmed that hand grip strength had a clear impact on the age and dexterity relationship. Together, the data presented in the PhD thesis suggest that other factors contribute to the effects of age on dexterity, and support the idea that better management of these confounding factors may allow for a better understanding of the age and dexterity relationship and furthermore, help older adults enjoy better movement dexterity