Much of the dual-task literature to date concentrates on unobstructed walking at self-selected gait speeds. This does not sufficiently assess the skills needed for functional mobility. A novel dual-tasking Functional Gait Assessment (FGA), which includes various tasks representative of everyday community ambulation, may give a better indication of functional ability and falls risk among community-dwelling older adults. Furthermore, executive function is considered most relevant during complex gait situations. However, previous studies used neuropsychological tests which typically only assess one feature of executive function. Further investigation of this relationship using a neuropsychological battery of tests is warranted.
Objectives:
The purpose of this study was to investigate age-related differences in dual-tasking ability on a novel dual-tasking FGA tool. A secondary aim was to assess whether a relationship exists between executive function and dual-tasking ability. It was hypothesised that dual-tasking would interfere with postural stability, presenting a greater challenge to healthy older adults, and that these dual-tasking effects would be related to executive function. This research could provide valuable information for future dual-task assessment and intervention protocols.
Methods:
A convenience sample of independently mobile, community-dwelling younger and older adults were recruited from King´s College London and the community, via flyers and word of mouth. Dual-tasking ability was assessed using a novel dual-tasking assessment in which concurrent tasks were incorporated into the Functional Gait Assessment (FGA). The manual dual-task involved carrying a glass of water (FGA-M). The cognitive dual-tasks involved numeracy (FGA-N) and literacy (FGA-L) related tasks. FGA scores under single and dual-task conditions together with associated dual-task costs and response accuracy were determined. Executive function was assessed using The Behavioural Assessment of the Dysexecutive Syndrome. A priori sample size calculation suggested that a minimum of 32 subjects per group was needed to achieve 80% power. The Mann Whitney U test and Spearman´s rank correlation was utilised to analyse the data obtained using SPSS version 22.
Results:
Forty-one community-dwelling healthy older (mean age = 68.3, male = 18) and younger adults (mean age = 37, male = 19) were recruited. The performance of cognitively demanding tasks while walking had a destabilising effect on dynamic balance for both younger and older adults (p ≤ 0.001). The resultant postural instability was however, more pronounced in the older participants (p ≤ 0.05), with performance under numeracy dual-task conditions significantly associated with falls risk (p ≤ 0.05). Executive function did not appear to be related to dual-tasking ability.
Conclusion(s):
This study utilised a novel dual-tasking FGA tool with findings providing additional evidence that attentional processes are involved in walking. The performance of attention-demanding cognitive tasks while walking had a negative effect on dynamic balance and could place older adults at a greater falls risk.
Implications:
Given the observed association between falls risk and dual-task interference, this standardised, quick to administer dual-task protocol, may have future application for multi-task training and falls risk assessment. However, future prospective research is warranted to investigate the effectiveness of this test at predicting falls.
The study was approved by the ethics committee at the National Hospital for Neurology and Neurosurgery, London.
