Mild Cognitive Impairment. Exercise Physiology Protects Patients for 1-3 Years

However, experts estimate that 30% to 40% of dementia is attributable to modifiable risk factors such as physical and cognitive inactivity.1 This suggests opportunities to prevent or at least delay the onset of dementia. At the population level, delay equals prevention because of lifespan. For instance, Zissimopoulos et al. predict that an intervention delaying dementia onset by one year could prevent 12% of dementia cases.

Fortunately, a first-of-its-kind study out of Sydney Medical School and universities across Australia suggests a dementia-delaying intervention may be readily available.3 It is well established that, for the elderly, various exercise and lifestyle changes can create improvements in cognition, but how long those improvements last is not well documented. Kathryn M Broadhouse (lead author / University of Sydney) and colleagues recently published the first study to follow patients with mild cognitive impairment (MCI) one year after cognitive interventions, measuring both cognition and hippocampal subregions.

The COGPACK multidomain, computer-based neurorehabilitation package had no effect at 18 months. However, highintensity, progressive resistance training resulted in global, long-term cognitive improvements. The improvements equated to reversing 0.7 years to 2.0 years of cognitive decline. Additionally, the supervised exercise intervention eliminated or mediated atrophy in hippocampal subfields related to Alzheimer’s disease. Extrapolating the linear trends evident at one year,

Broadhouse et al. estimate that this exercise intervention could preserve hippocampal substructures for roughly three years. While one might assume that the effects of an exercise intervention would gradually or quickly dissipate at the end of an exercise intervention, researchers found the opposite. Their MRI data suggests that distinct mechanisms emerge during and after training to create a cascading therapeutic mechanism that supports cognition.

While various exercise interventions may reverse cognitive decline long-term, researchers in this first-of-its-kind study demonstrated the efficacy of one specific intervention and may have disproved the value of other activity-related factors. The successful intervention involved resistance exercise at 80% of peak capacity, continuously progressed. This required the supervision of an exercise physiologist or physiotherapist. Supervised exercise intervention lasted six months, and final measures were taken one year after the cessation of the six-month intervention.

The exercises involved three sets of eight repetitions in resistance machines, targeting five or six body regions: chest press, leg press, seated row, standing hip abduction, and knee extension. On the other hand, neither general physical activity nor change in fitness over the 18 months affected the trajectory of hippocampal atrophy. This demonstrates that the protective effects observed for the hippocampus were not simply the results of activity or fitness, but were more likely related to specific effects of a specific exercise intervention. The lack of association between general physical activity and hippocampal protection also suggests that some exercise interventions may not work as well as others for reversing cognitive decline.

Research is ongoing. We are likely to see improved understanding regarding the types of exercise, length of intervention, and how often interventions need to be repeated. Healthcare now has good evidence supporting the practice of prescribing supervised exercise to reverse cognitive decline. The intervention needs to be properly supervised to ensure progressive, high-intensity levels as well as patient safety. The interventions also need to be research-based, as it seems not all physical activity creates these effects. 

References

1. Livingston G, Sommerlad A, Orgeta V, Costafreda SG, Huntley J, Ames D, Ballard C, Banerjee S, Burns A, Cohen-Mansfield J, Cooper C. Dementia prevention, intervention, and care. The Lancet. 2017 Dec 16;390 (10113):2673-734.

2. Zissimopoulos J, Crimmins E, St. Clair P. The value of delaying Alzheimer’s disease onset. InForum for Health Economics and Policy 2015 Jan 1 (Vol. 18, No. 1, pp. 25-39). De Gruyter.

3. Broadhouse KM, Singh MF, Suo C, Gates N, Wen W, Brodaty H, Jain N, Wilson GC, Meiklejohn J, Singh N, Baune BT. Hippocampal plasticity underpins long-term cognitive gains from resistance exercise in MCI. N