Exercise as it relates to Disease/Can physical activity improve cognitive and motor function in patients with Dementia?

This is a critique of a 2015 article A 9-Week Aerobic and Strength Training Program Improves Cognitive and Motor Function in Patients with Dementia: A Randomized, Controlled Trial, published in the American Journal of Geriatric Psychiatry.

What is the background to this research?
Dementia is associated with a decline in cognitive and motor function, which results in the need for daily assistance and care. Dementia is on the rise, and is expected to elicit an ever increasing burden on social and fiscal systems, making it a public health priority.

Currently, there is no cure for dementia. Medications exist to slow the key elements of cognitive decline. The cost-effective nature of these medicines however, is highly controversial, as are the associated side effects. Moreover, these medications fail to combat the decline in motor skills associated with dementia, including the continued loss of endurance, muscle strength, mobility and balance. Therefore, there is an urgent need for affordable alternative treatments to counteract the cognitive and motor decline of patients suffering from dementia.

Previous studies have provided results which are highly inconsistent. Some studies have found a moderate association between aerobic exercise and cognitive improvements, whilst others have found there to be no significant effect. Of these studies, those which investigated the effects of both aerobic and strength training on cognitive function in healthy, older adults found the strongest benefits. Therefore, the study in question hypothesised a combination of aerobic and strength training would elict greater benefits than single-compartment exercise (aerobic only) vis-à-vis cognitive and motor function in patients with dementia.

Where is the research from?
This study was conducted in the Netherlands, and published in The American Journal of Geriatric Psychiatry. The paper was attributed to a collaboration of several reputable authors. The majority of these authors are based at the Center for Human Movement Sciences at the University of Groningen. Others were based in areas such as rehabilitation, elderly care medicine and neuropsychology. Many of these authors have published articles investigating the relationship between exercise, cognitive function and dementia- both before and after publishing this article. The research was financially supported by Fonds NutsOhra (FNO), a Netherlands based health and disability research fund. The authors state FNO had no role in study design, data collection, analysis, decision to publish, or manuscript preparation. In addition, the authors declared no conflicts of interest.

What kind of research was this?
This research was a randomised control trial with three intervention groups. Randomised control trials are highly effective in evaluating the effectiveness of interventions and are considered the gold standard in data collection.

What did the research involve?
The research compared the effects of a 9-week intervention on cognitive and motor functions in institutionalised patients with dementia over the age of 70. Participants were assigned to one of three intervention groups: combined aerobic and strength exercise (combined group) (n = 37), aerobic-only exercise (aerobic group) (n = 36), and social support visits (social groups) (n = 36). The sample size of 109 participants is sufficient to generate meaningful data. Post tests were conducted after the 9-week intervention and follow-up tests 9 weeks thereafter. Participants also had to meet various eligibility criteria.

Each group participated in 36 individualised, 30 minute sessions. The combined group participated in two strength sessions and two walking sessions per week. These sessions were alternated. The aerobic group participated in four walking sessions per week and the social group participated in four social visits per week.

Strength exercises for the combined group focused on lower-limb strengthening and consisted of seated knee extension, plantar flexion through toe raises while holding both hands of the trainer, hip abduction by moving the straight leg sideways while holding onto a surface and hip extension by moving the straight leg backwards while holding onto a surface. The combined and aerobic group performed moderate to high intensity walking sessions.

As a follow-up assessment of cognitive function, a neurophysiological battery test was conducted. Both short and long term visual and verbal memory were assessed, as were executive function. To assess motor function, a physical battery test was conducted focusing on walking endurance, leg strength, mobility and balance.

There are several limitations which this study has. Primarily, the sample of dementia patients is limited to those who are able and willing, hence there would be less or no severe cases. This is problematic because, when determining the effectiveness of the intervention, it does not account for cases which are more severe. Hence, it is difficult to know if the intervention would improve patients symptoms, slow down the decline of their illness, or do nothing at all for patients with more severe symptoms. Finally, while 9 weeks may be sufficient to comment on the shorter term effects, it by no means provides the scope or scale to comment on the medium to longer term effects of a degenerative condition such as dementia.

What were the basic results?
Relative to the social group, the combined group improved on cognitive function, visual memory, verbal memory and executive function. The aerobic group varied only from the social group in relation to improved executive function. In the motor domain, intervention showed significant effects in the walking endurance, leg muscle strength and balance of participants. The combined group improved relative to the social group on walking endurance, leg muscle strength and balance. Moreover, comparisons revealed that the combined group scored higher than the aerobic group in walking endurance and leg muscle strength. After the 9-week follow up test no significant improvements in cognitive or motor function remained.

What conclusions can we take from this research?
The study provides evidence which suggests the effectiveness of a combined aerobic and strength training program to improve cognitive and motor function in patients with dementia. Furthermore, a combination of aerobic and strength training is more effective than aerobic only training.

Dementia is associated with global cognitive decline and is assessed using a Mini-Mental State Exam (MMSE). Compared with the aerobic only and social groups, the combined group significantly improved their MMSE scores, indicating a combination of aerobic and strength training reduces global cognitive decline in patients with dementia.

In addition, a combination of aerobic and strength training can improve verbal memory, visual memory and executive function. These conclusions are consistent with those of a 6-week pilot study investigating the effects of exercise on cognitive function. The study found only a moderately significant intervention effect on visual memory, whereas the current study found greater improvements in all domains of cognitive function. These more meaningful findings can be explained by the longer training period, indicating the importance of ongoing engagement in exercise in improving cognitive function.

Practical advice
Older adults suffering from dementia are likely to experience cognitive and motor benefits from engaging in a combination aerobic and strength training.

Two 30 minute aerobic and two 30 minute strength sessions per week is a strong starting position. Aerobic activities should be physically undemanding and may include walking or stationary cycling. Strength training exercises should focus primarily on lower limb strengthening. Progression and monitoring of exercise engagement among this population should be managed by health professionals.

A well structured and ongoing training plan is an important consideration when seeking to slow disease progression, as well as maintain the positive effects of exercise in patients with dementia.

Further information/resources
Dementia Australia

The Dementia Centre

Clearing house for Sport: Sport and Mature Age Physical Activity

[https://www.healthdirect.gov.au/physical-activity-guidelines-for-older-adults#:~:text=It's%20recommended%20that%20adults%20aged,weight%2C%20health%20problems%20or%20abilities. Physical activity guidelines for older adults]