Completing activities of daily life relies on using both cognitive and physical resourcesefficiently, but these are affected by age. This may be due either to an age-related reductionin the resources we have available for carrying out tasks or to a reduction in our ability to usethese resources efficiently. These resources comprise a set of processes called executivefunctions (EF), which collectively allow us to plan, initiate and monitor our performance ofactivities. Control and allocation of these resources is attributed to a central mechanism,sometimes called the central executive or executive attention, but the parameters thatdetermine how resources are allocated are not well understood. Even simple or apparentlyautomatic activities, such as walking, require attention, meaning that when task demandsincrease, for example when walking and speaking on the phone, there is a loss of efficiencyin both tasks. The dual-task (DT) paradigm is an empirical means of examining the wayattentional resources are allocated between two tasks by comparing their performancetogether in relation to how well they are carried out singly. Asking people to perform acognitive task, such as counting backwards or spelling, while walking provides a reasonablynaturalistic way to examine how flexibly older adults can divide their attention between thetwo tasks. Manipulating the demands of the task, either by increasing the difficulty of thecognitive task or instructing the participants to focus on one task or the other (prioritisation)should illuminate the strategies they use to allocate their available attention between the twotasks ask task demands vary. To explore this hypothesis a cohort of physically andcognitively healthy community-dwelling older adults (mean age = 72.3 years) took part inthree studies. In the first experiment, 72 participants completed 8 single and dual-taskconditions with varying cognitive load (counting back in 3s and 7s) and attentionprioritisation (no prioritisation, prioritising walking and prioritising counting). Instructing theparticipants to prioritise walking in the DT when counting back in 7s produced the bestwalking and counting performance and this was predicted their score on a standardisedmeasure of cognitive flexibility. In second part of the study, 68 of the participants were tested12 months later when there was improvement in both their single and dual-task performances.There was also decline in concurrent walking and counting performance, but only whenattention was allocated to walking in preference to the cognitive task. Both the improvementsand the decline in performance after the 12-month period were predicted by a standardisedtest for EF at T1. In the third study a separate group of older adults (73.2 years) was trainedto walk rhythmically to music, to further investigate the external manipulation of resource-allocation during concurrent walking and counting. Their performances were compared to 2control groups who did not receive the same intervention procedures. Overall findings fromthis doctoral research demonstrate that explicitly manipulating attention-allocation duringconcurrent walking and cognitive activity improved healthy older adults’ walking andcounting performance and this was strongly associated with better cognitive flexibility. After12 months, subtle decline in ability to allocate attention to walking during the DT, whenattentional-demands were high, was also predicted by cognitive flexibility in an EF task.Together, these findings illuminated the role of executive attention in a rapidly-changingcomplex task when the ‘wrong’ prioritisation could result in a fall. Observing healthy olderadults’ cognitive flexibility in allocating attention to walking, when required, revealed thatexecutive attention was key to the future maintenance of their current functional well-being.
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The role of executive attention in healthy older adults' concurrent walking and counting
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