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Trial finds exercise not slowing cognitive impairment in dementia

Moderate to high intensity exercise does not slow cognitive impairment in older people with dementia, finds a University of Oxford trial. Although the exercise programme improved physical fitness, it cannot be recommended as a treatment option for cognitive impairment in dementia, say the researchers.

Nearly 47.5m people worldwide have dementia and the view that exercise might slow cognitive decline has gained widespread popularity. But recent reviews of trials of exercise training in people with dementia have shown conflicting results.

To try and resolve this uncertainty, a team led by researchers at the Centre for Rehabilitation Research and Centre for Statistics in Medicine, Nuffield department of orthopaedics rheumatology & musculoskeletal sciences, Botnar Research Centre, University of Oxford, decided to estimate the effect of a moderate to high intensity aerobic and strength exercise training programme on cognitive impairment and other outcomes in people with dementia.

The trial involved 494 people with mild to moderate dementia (average age 77 years) living in the community across 15 regions of England. General health and fitness was assessed at the start of the study and participants were randomly assigned to either a supervised exercise and support programme (329 patients) or to usual care (165 patients).

The programme consisted of 60 min-90 min group sessions in a gym twice a week for four months, plus home exercises for one additional hour each week with ongoing support.

The main (primary) outcome was an Alzheimer’s disease assessment score (ADAS-cog) at 12 months. Other (secondary) outcomes included activities of daily living, number of falls, and quality of life. Compliance with exercise was good and participants were assessed again at six and 12 months.

After taking account of potentially influential factors, the researchers found that cognitive impairment declined over the 12-month follow-up in both groups. The exercise group showed improved physical fitness in the short term, but higher ADAS-cog scores at 12 months (25.2 v 23.8) compared with the usual care group, indicating worse cognitive impairment. However, the average difference was small and clinical relevance was uncertain.

No differences were found in secondary outcomes, including number of falls and quality of life, or after further analyses to test the strength of the results.

The researchers point to some trial limitations. For example, participants and carers knew which group they were in, and the period of structured exercise may have been too short to produce positive benefits. However, strengths over previous trials included a substantially larger sample size and high levels of follow-up.

“This trial suggests that people with mild to moderate dementia can engage and comply with moderate to high intensity aerobic and strengthening exercise and improve physical fitness,” say the authors.

“These benefits do not, however, translate into improvements in cognitive impairment, activities in daily living, behaviour, or health related quality of life,” they add. They suggest that future trials should explore other forms of exercise, and that investigators “should consider the possibility that some types of exercise intervention might worsen cognitive impairment.”

Abstract
Objective: To estimate the effect of a moderate to high intensity aerobic and strength exercise training programme on cognitive impairment and other outcomes in people with mild to moderate dementia.
Design: Multicentre, pragmatic, investigator masked, randomised controlled trial.
Setting: National Health Service primary care, community and memory services, dementia research registers, and voluntary sector providers in 15 English regions.
Participants: 494 people with dementia: 329 were assigned to an aerobic and strength exercise programme and 165 were assigned to usual care. Random allocation was 2:1 in favour of the exercise arm.
Interventions: Usual care plus four months of supervised exercise and support for ongoing physical activity, or usual care only. Interventions were delivered in community gym facilities and NHS premises.
Main outcome measures: The primary outcome was score on the Alzheimer’s disease assessment scale-cognitive subscale (ADAS-cog) at 12 months. Secondary outcomes included activities of daily living, neuropsychiatric symptoms, health related quality of life, and carer quality of life and burden. Physical fitness (including the six minute walk test) was measured in the exercise arm during the intervention.
Results: The average age of participants was 77 (SD 7.9) years and 301/494 (61%) were men. By 12 months the mean ADAS-cog score had increased to 25.2 (SD 12.3) in the exercise arm and 23.8 (SD 10.4) in the usual care arm (adjusted between group difference −1.4, 95% confidence interval −2.6 to −0.2, P=0.03). This indicates greater cognitive impairment in the exercise group, although the average difference is small and clinical relevance uncertain. No differences were found in secondary outcomes or preplanned subgroup analyses by dementia type (Alzheimer’s disease or other), severity of cognitive impairment, sex, and mobility. Compliance with exercise was good. Over 65% of participants (214/329) attended more than three quarters of scheduled sessions. Six minute walking distance improved over six weeks (mean change 18.1 m, 95% confidence interval 11.6 m to 24.6 m).
Conclusion: A moderate to high intensity aerobic and strength exercise training programme does not slow cognitive impairment in people with mild to moderate dementia. The exercise training programme improved physical fitness, but there were no noticeable improvements in other clinical outcomes.

Authors
Sarah E Lamb, Bart Sheehan, Nicky Atherton, Vivien Nichols, Helen Collins, Dipesh Mistry, Sukhdeep Dosanjh, Anne Marie Slowther, Iftekhar Khan, Stavros Petrou, Ranjit Lall

[link url="https://www.bmj.com/company/newsroom/moderate-to-high-intensity-exercise-does-not-slow-cognitive-decline-in-people-with-dementia/"]BMJ material[/link]
[link url="https://www.bmj.com/content/361/bmj.k1675"]BMJ abstract[/link]

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