We know without doubt that physical activity is good for the brain and has the potential to reduce the risk and onset of dementia. The key questions now are what sort of physical activity, how often, how hard – and whose decisions are they anyway?
When we know those answers, we’ll have a better chance of developing exercise routines that people will embrace, enjoy and stick with. That’s the main driver behind a comprehensive research program currently under way in the Samson Institute.
Research Fellow Dr Ashleigh Smith and colleagues from a range of disciplines – both within and outside ARENA – are investigating the most suitable exercise interventions for slowing age-related cognitive decline. The work builds on the novel concept that individuals are often best equipped to set their own exercise intensity.
“We’ve started to move away from that medical model of exercise prescription where you go to a personal trainer or someone who is going to set out a program and they say ‘we want you to work so your heart rate is at this particular intensity’,” Dr Smith said. “That mode of prescription takes the control away from the person”.
“Previous work with young adults has found that if you ask someone to exercise at an intensity they find somewhat hard, they will choose an intensity where they’ll feel positive and good about themselves during the activity, but the intensity will also lead to improvements in cardiovascular health after an intervention. They choose an intensity that will actually work and can be maintained.
“What we didn’t know until recently is if older adults, and potentially older adults with cognitive impairment, are able to regulate their exercise in the same way.”
The initial findings indicate that older adults choose an intensity around what is known as the ventilatory threshold, where they move from using a primarily aerobic energy source to an anaerobic source. They get results, enjoy the experience, and don’t risk over-exercising or withdrawing from the program by aiming too high because someone prescribed the wrong intensity.
For Dr Smith, whose research is funded by Alzheimer’s Australia, the important next stage is to determine to what extent we should cater for cognitive factors during exercise prescription when working with people who have mild cognitive impairment and thus are at risk of dementia, in part because of sedentary lifestyles.
“In our current work we are looking at older adults with and without cognitive impairment and also at two different modes of exercise: a standard exercise bike and one with a computer interface, which means they have to steer and change gears and interact with other road users,” she said.
“When you increase the cognitive load do people choose the same activity level? Are they distracted by having to think and to steer rather than just pedal? Do they pick a higher level, to try to catch up with other road users, or do they pick a lower level because of the additional cognitive challenge? Does increasing cognitive load during exercise lead to even greater brain health benefits then standard exercise?”
At the same time, other researchers are looking at other barriers to people with cognitive impairment taking on an exercise program, including, for example, that they are no longer able to drive to get to a gym or don’t feel comfortable walking around in their neighbourhood. “There are a lot of interesting pieces to the puzzle,” Dr Smith said.
Two figures underpin the importance of this work. Worldwide, 30% of cases of Alzheimer’s disease are attributed to increased modifiable risk factors, including low physical activity and heightened cardiovascular risk. In Australia, as many as 50% of people drop out of a moderately prescribed exercise intervention model prepared for them.