Regular Research Article
A 9-Week Aerobic and Strength Training Program Improves Cognitive and Motor Function in Patients with Dementia: A Randomized, Controlled Trial

https://doi.org/10.1016/j.jagp.2014.12.191Get rights and content

Objective

To compare training and follow-up effects of combined aerobic and strength training versus aerobic-only training on cognitive and motor function in institutionalized patients with dementia and to explore whether improved motor function mediates improved cognitive function.

Methods

Using a 9-week, parallel, three-group, single-blind, randomized, controlled trial with a follow-up assessment at week 18, we assessed 109 patients with dementia (age 85.5 ± 5.1 years) in a psycho-geriatric nursing home. Each 9-week intervention consisted of 36, 30-minute sessions. A combined group (N = 37) received and completed two strength and two walking sessions per week, an aerobic group (N = 36) completed four walking sessions, and a social group (N = 36) completed four social visits per week. Cognitive and motor functions were assessed at baseline, after the 9-week intervention, and after a consecutive 9 weeks of usual care.

Results

Baseline corrected post-test scores in the combined versus the social group were higher for global cognition, visual memory, verbal memory, executive function, walking endurance, leg muscle strength, and balance. Aerobic versus social group scores were higher for executive function. Follow-up effects reversed toward baseline values. Motor improvement did not significantly mediate cognitive improvement.

Conclusion

Compared with a nonexercise control group, a combination of aerobic and strength training is more effective than aerobic-only training in slowing cognitive and motor decline in patients with dementia. No mediating effects between improvements in cognitive function via improved motor function were found. Future research into the underlying mechanistic associations is needed.

Introduction

Dementia is associated with a decline in cognitive and motor function that in turn necessitates increasing daily assistance and care. As a care-intensive condition, dementia is expected to exact a severe social and financial impact, making it a public health priority.1

To date there is no cure for dementia. Pharmacologic treatments attempt to slow the decline in key elements of cognitive functions, including memory and executive function. However, the clinical and cost-effectiveness of these pharmacologic treatments are controversial, and the medications may cause side effects.2 Moreover, current medications fail to counteract the motor decline associated with dementia, as illustrated by the continued loss of endurance, muscle strength, mobility, and balance.3 Therefore, there is an urgent need for affordable alternative treatments to combat both the cognitive and motor decline of patients with dementia, preferably with fewer or no side effects.

In light of the recent recognition by the American College of Sports Medicine that “exercise is medicine,” exercise is suggested to be a potential treatment for slowing a dementia patient's decline in cognitive and motor function.4, 5 However, potential cognitive benefits of exercise treatment should be interpreted with caution because the results have been inconsistent.4, 6 Small to moderate improvements in mixed cognitive domains (e.g., communication, global cognition, executive function, memory) were found after mainly aerobic exercise (i.e., walking, cycling),7, 8, 9, 10 whereas similar aerobic exercise studies in patients with dementia found no effects.11, 12 In studies consisting of healthy older people, a combination of aerobic and strength training showed the strongest effects in improving cognitive function compared with single-component aerobic or strength interventions.13 Therefore, we suggest that after combined training these beneficial effects might also apply to patients with dementia. However, the effects of combined exercise training on cognition have not yet been studied in patients with dementia.

Based on previous evidence in healthy older people,13 we hypothesized that combining aerobic and strength training in patients with dementia will result in stronger effects on cognitive function than aerobic-only training. Leg muscle strength training (e.g., m. quadriceps femoris, m. gastrocnemius, m. biceps femoris) has the potential to improve motor function, such as balance and mobility.14, 15 These motor improvements may promote higher aerobic training ability, thereby eliciting higher metabolic and cardiovascular responses. With these higher exercise responses, a mediating cascade of neuromotor events may be initiated.15, 16, 17, 18, 19

A pilot study we previously conducted showed that alternating aerobic and strength training sessions is safe and feasible for patients with dementia.20 The potentially favorable motor and cognitive responses in the pilot study prompted us to launch a large-scale randomized controlled trial. The objectives of the present study compare the training and follow-up effects of a combined aerobic and strength versus an aerobic-only intervention on cognitive and motor function in patients with dementia. Furthermore, we examine whether cognitive change is mediated by a change in motor function.

Section snippets

Methods

The Medical Ethics Committee of the University Medical Center Groningen approved the research protocol. Patients orally agreed to participate and in conjunction their legal representative gave written consent.

Participant Characteristics and Compliance with the Intervention

Figure 1 shows the study design and patient flow. In total, 495 patients were screened for eligibility, and 132 were enrolled in the study. There were no significant between-group differences for descriptive characteristics, and the severity of dementia ranged between mild to severe dementia (Table 1).21 Table 2 presents the training characteristics for each group. After exercise the mean heart rate increased more in the combined and aerobic groups than in the social group (Table 2).

Intervention Effects

Results on

Discussion

This is the first study that provides evidence for the effectiveness of a combined aerobic and strength training program to improve cognitive and motor function in older patients with dementia. Cognitive and motor function improved after 9 weeks of training. Moreover, an alternating form of aerobic and strength training sessions were more effective than aerobic-only training.

Patients with dementia suffer from a continuous loss in global cognition.34 Previous studies show an average 12-month

Conclusion

We conclude that compared with a nonexercise control group, a combination of aerobic and strength training elicits stronger effects than the aerobic-only training in slowing the cognitive and motor function decline in institutionalized patients with dementia. However, we did not confirm that improved motor function mediates improved cognitive function. Future research is needed to study the underlying mechanisms that are involved in the link between exercise and the cognitive and motor

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