Exercise as it relates to Disease/The effects of moderate to high intensity exercise on Dementia

This is an analysis of the journal article “Dementia And Physical Activity(DAPA) trial of moderate to high intensity exercise training for people with dementia: randomised controlled trial” by Lamb et al. (2018).

What is the background to this research?
Dementia is a term used to describe a number of disorders resulting in the progressive loss of cognitive and motor function. There is currently no cure and the condition is most common in individuals 65 years and older. Due to the ageing population, dementia is becoming more prevalent in developed countries. Currently an estimated 46.8 million people worldwide are affected with an expected increase to 131.5 million by 2050. This places considerable pressure on public health and social services. In 2015 the estimated global cost of dementia was US$818 billion.

To date, finding a cure has proven problematic due to the number of types and causes of dementia, difficulties in diagnosing early neurodegenerative changes and the rate of cognitive impairment associated with each cause. Dementia research and development has primarily focused on drug treatments and symptom management. However the complexities of the condition have lead to numerous drug trial failures. Some pharmaceutical companies are leaving the research market due to the costs associated with the challenges of developing drugs for multifaceted conditions.

Studies indicate that exercise may slow cognitive decline in mild to moderate cases of dementia. A pharmaceutical cure is not in the foreseeable future, however, exercise could provide an affordable and accessible alternative intervention strategy to reducing neurodegenerative progression in some dementia patients. In 2012 the UK government made dementia research a national priority. The DAPA trial was commissioned for the purpose of advising the debate.

Where is the research from?
A team of UK researchers with extensive experience in clinical studies, rehabilitation and exercise testing, sought dementia patients from memory clinics across 15 English regions and conducted the study in community gym settings. In addition to the Coventry and Warwickshire Partnership Trust, research was undertaken in the following university departments:

University of Oxford
 * Centre for Rehabilitation Research and Centre for Statistics in Medicine
 * Nuffield Department of Orthopaedics Rheumatology & Musculoskeletal Sciences
 * Botnar Research Centre
 * Oxford University Hospitals NHS Foundation Trust

University of Warwick
 * Warwick Clinical Trials Unit
 * Division of Health Sciences

An independent steering committee, and a data monitoring and ethics committee oversaw the trial. Funding bodies and the study sponsor undertook no role in the research or its outcomes. Researchers stated they had no conflict of interest.

What kind of research was this?
Research was conducted as an investigator masked, random, controlled trial over 12 months and included cognitive testing and participant/carer interviews. A study protocol ensured safety of participants and data integrity.

What did the research involve?
Participants with Alzheimer's and vascular type dementia were assessed for eligibility by the following criteria:
 * Clinical diagnosis of dementia in accordance to the Diagnostic and Statistical Manual of Mental Disorders, fourth edition
 * Mini Mental State Examination score >10
 * Able to sit in a chair
 * Able to walk 10 feet without assistance
 * Live within the community alone or with others

Baseline assessments were made and 494 participants randomly allocated to two groups, intervention (aerobic and strengthening exercise program) or control (usual care) at 2:1 in favour of intervention. In addition to usual care, the intervention group undertook a supervised exercise program over four months after which participants moved to an unsupervised home based program with ongoing support.

The primary measure for this study was The Alzheimer's disease assessment scale-cognitive subscale (ADAS), the most common form of cognitive evaluation used in trial conditions allowing the data to be comparable with other research. Secondary measures included other forms of neurological assessment, fitness testing and participant/carer interviews.

The study contains several restrictions and may have benefited from a wider collection of data and a longer period of supervised exercise. The control and intervention groups were assessed at six and 12 months from baseline assessment. These results may be immature as supervised exercise was only undertaken for four months. Some studies suggest 6–12 months of regular exercise is required for demonstrated cognitive improvement. Also, full compliance during the unsupervised exercise period cannot be guaranteed. Symptoms of dementia include confusion, memory loss and lack of motivation, therefore self-reports are unreliable and carer observations may contain bias.

Physical fitness data was not collected from the control group or during the intervention group's unsupervised exercise period. Adverse event data was only recorded for the intervention group. Given the physical fitness data is incomplete and may contain participant/carer bias, comparisons and conclusions drawn from the study regarding physical fitness of participants are not definitive.

What were the basic results?
ADAS applies a scale of 0–70 with higher scores demonstrating higher degrees of cognitive impairment. A person free of dementia could expect to score five. The mean baseline assessment ADAS scores of the primary sample were 21.4 (SD 7.8) for the control group and 21.2 (SD 9.5) for the intervention group. At the six-month assessment both groups demonstrated increases in cognitive impairment with mean ADAS scores of 22.4 (SD 9.4) and 22.9 (SD 11.6) respectively. Testing at 12 months indicated further cognitive decline in both groups with mean ADAS scores of 23.8 (SD 10.4) and 25.2 (SD12.3) respectively. The greatest cognitive decline occurred in the intervention group with a 4-point increase in mean ADAS. Almost double that of the control group.

Evaluation of secondary measures demonstrated quality of daily living, behavioural symptoms and carer stress deteriorated for both groups during the study. Overall quality of life decreased with only very minimal increases in some subsets. However, physical fitness did improve.

Lamb et al. concluded there was no positive correlation between moderate to high intensity aerobic and strengthening exercise programs and slowing cognitive decline in mild to moderate dementia patients. The ADAS scores indicate it is possible intervention may have intensified cognitive degeneration. The study also concluded that any improvements in physical fitness did not transfer to improved quality of living for participant or carer.

What conclusions can we take from this research?
The research concludes exercise cannot be recommended as a treatment for cognitive decline in dementia patients. This topic has been the subject of numerous studies, however the research has culminated in mixed results. While this study concluded a negative response, there have been sufficient positive responses    to suggest further research. Given this study's inferences regarding the effects of short-term aerobic and strengthening exercise on cognitive decline in dementia patients, investigation into types, duration and intensity of exercise seems warranted.

Practical advice
While the effect of exercise on slowing cognitive decline in mild to moderate dementia patients remains unclear, regular physical activity has overall health benefits that can enhance wellbeing, improve social engagement and induce positive emotional responses. Prior to undertaking exercise individuals should seek medical advice from a licensed practitioner to determine risk factors.