Effects of Step Training in Older Adults with Mild Dementia

Falls are common in older adults with mild dementia (OWMD), and they are the leading cause of functional dependence, morbidity, and mortality in this population. The ability to take rapid, accurate, and effective steps in varied environmental conditions, such as walking on a wet floor or rough terrain, is crucial to ensuring safety and avoiding falls. OWMD often have difficulties in choice stepping (i.e., stepping on a specific target, while avoiding irrelevant distractions), which requires high levels of sensorimotor and cognitive function. As impaired choice stepping has been shown to predict falls in the general older population, improving choice stepping is expected to reduce the risk of falls in OWMD.

Step training has been shown to be effective at reducing the incidence of falls and improving related risk factors, including choice stepping, in healthy older adults. However, the effects of step training have not been investigated in OWMD. The primary objective of the proposed project will be to assess the effects of a step-training program involving concurrent stepping and visuospatial tasks on choice stepping, prefrontal cortex functioning during choice stepping, and fall-related outcomes (i.e., step length, lower-limb muscle strength, balance, mobility, dual-task ability, and fear of falling) in OWMD.

The prefrontal cortex is responsible for the executive functions such as attention and inhibitory function, which are integral to choice stepping reaction time tasks. However, the effects of step training on prefrontal cortex functioning during choice stepping in OWMD remain unclear. The neural mechanisms underlying the potential effects of step training on choice stepping have never been investigated in this population. Therefore, the secondary objective of the proposed project will be to evaluate the mediating effects of changes in the prefrontal cortex functioning during choice stepping on the potential benefits of a step-training program for choice stepping in OWMD.

The proposed project will provide robust evidence to support the use of step training to improve choice stepping and reduce the risk of falls in OWMD. Disentangling the neural mechanisms underlying the effects of step training will be crucial to the development of the most effective interventions to target these mechanisms. Furthermore, the scientific evidence derived from the proposed project will motivate patients, caregivers, and clinicians to participate in such programs, and subsequently, relieve the fall-related burdens on multiple stakeholders.

Inclusion criteria

• at least 65 years old;
• have a physician's diagnosis of dementia according to the Diagnostic and Statistical Manual of Mental Disorders 5th edition;
• have mild dementia, indicated by a score of 10 or higher on the Montreal Cognitive Assessment Hong Kong version (HK-MoCA);
• able to walk 10 meters independently without a walking aid;
• receiving care by an unpaid "main caregiver" with at least 3.5 hours of face-to-face contact per week.

Exclusion criteria

• unable to perform step training due to unstable or severe musculoskeletal, cardiorespiratory, or neurological conditions;
• have severe hearing and/or visual impairments that limit their ability to communicate;
• have been hospitalized within the past 30 days.