Have you ever forgotten where your personal belongings are placed? Have you ever been unable to recall the names of your good friends? Have you ever failed to recall any recent conversations? If it is a ‘yes’ for all these questions, you probably have mild cognitive impairment (MCI).
MCI is a kind of cognitive malfunction with a significant memory problem. However, unlike the more severe Alzheimer’s disease, it doesn’t affect your daily function yet, at this moment. It is estimated that around 14%–18% of older adults aged 70 or older have MCI. It has been found to be a transitional phase between healthy ageing and dementia, which means the chance of people with MCI developing dementia is greater than normal adults. To delay further cognitive decline, early intervention is needed before any functional impairment becomes evident.
Physical activity (PA) and exercise training have been found to be possibly effective in preventing cognitive decline in people with MCI. A number of research studies have been done to investigate what kind of PA and exercise training improves cognitive function in people with MCI. Although the evidence is not strong at the moment, we are still able to identify some studies which demonstrated positive findings.
Moderate intensity PA training has been shown to be effective in delaying cognitive decline. In one study, people with subjective memory complaints or objective diagnoses of MCI were randomised to a 24-week home-based intervention. Participants were asked to perform three 50-minute sessions of PA each week. They can choose walking or other forms of exercise, such as strength training, based on their preference and exercise levels. A newsletter was mailed to the participants periodically as a reminder of the key messages of the programme. They were also given a workbook that included information on exercise, goal setting, time management, and safety issues. Participants were found to have improved cognition at the end of the programme at six months, and the effects sustained at 18 months. The study, however, demonstrated no significant change in depressive symptoms and quality of life.
In another study, using a multi-component exercise programme as the intervention, people with MCI participated in bi-weekly 90-minute exercise for six months. The exercise intervention consisted of aerobic, muscle strengthening, postural balance, dual-task training, and outdoor walking. Participants were also instructed to perform home-based muscle strengthening and walking exercises daily. Although the study found no significant improvement in participants in general, the subgroup analysis showed that participants with amnestic MCI had improved general cognitive function and logical memory, and reduced whole-brain cortical atrophy.
The effects of resistance and aerobic exercise training on cognition have also been investigated individually in another study. Participants were randomised to resistance training, aerobic training or balance and tone training (control group). Those in resistance training performed 6–8 repetitions for two sets for each exercise using pneumatic air pressurised systems. Progression was made when the participants were able to complete two sets of exercises in great form. Those in the aerobic programme practised outdoor walking, which started at 40% of heart rate reserve and progressed to 70%–80%. Those in balance and tone training received simple stretching, balance exercise, and relaxation techniques. All participants practised exercise for 60 minutes twice per week. The results showed that the resistance group had significant improvement in attention and associative memory performance, while the aerobic group had a better general physical function, including balance control, mobility, and functional movement.
There are some studies showing that PA and exercise training has positive effects on cognition. However, the huge variation in the design of training suggested that we could not conclude which type, intensity, duration, and frequency of exercise training is the most suitable one for improving cognition. Further studies are required to make a concrete conclusion on what the most effective PA and exercise training is and how the training should be carried out. Physiotherapists, who are specialists for promoting active ageing in older adults, have a key role in applying and designing treatments for people with MCI to promote their cognition and physical capacity, and reduce related signs and symptoms. As more evidence is going to emerge, PA and exercise training can possibly become one of the key components in treating people with MCI.
Wayne Chan is a registered physiotherapist at Chi Lin Nunnery Elderly Services and a visiting lecturer at The Hong Kong Polytechnic University. He is interested in geriatric rehabilitation, dementia, and active ageing. He is on Twitter.