AAN 2013 Highlight: Research Suggests Benefits of Exercise and Cognitive Leisure Activities in Improving Cognitive Function in Patients with MS
A series of abstracts were presented by scientists from the Kessler Foundation Institute for Stroke Rehabilitation at this year’s American Academy of Neurology meeting examining brain function and structure in patients with MS and the effects of exercise and cognitive leisure activities in protecting against cognitive decline associated with MS.1
Cognitive leisure activities provide protection against MS-related cognitive decline independent of genetically determined factors
Sumowski and colleagues reported results from a study examining two different factors and their ability to protect against MS-related cognitive decline.2 These factors include brain reserve (BR), defined as greater lifetime brain growth/size, and cognitive reserve (CR), defined as lifetime enrichment through cognitive leisure. The research were trying to determine whether BR and CR may provide protection against cognitive decline that occurs in MS.
Previous research has shown that BR protects against cognitive decline related to aging and Alzheimer’s disease, however there is no research supporting a similar role for BR in MS. By contrast, CR has been shown to protect against cognitive decline in both MS and Alzheimer’s disease. However, it is not clear whether CR provides protection on its own, independently of BR.
The study was conducted in 62 patients with MS and used MRI scans to measure MS-related damage to brain tissue and BR (intracranial volume). CR was measured using a survey of early life cognitive leisure and education. Additionally, standardized tests were used to measure cognitive efficiency (how well patients did with certain basic tasks involving thinking and decision-making) and memory. The study found that both BR and CR independently protected against cognitive decline. However, each of these factors appeared to work differently. Greater intracranial volume was associated with decreased impact of existing brain tissue damage on cognition. In other words, the greater the size of the brain, the less MS-related damage impacted thinking and decision-making ability. However, while BR appeared to protect against loss of cognitive efficiency, it did not protect against memory decline. On the other hand, CR (greater history of cognitive leisure activities) appeared to decrease the impact of MS-related brain tissue damage on cognitive status independent of BR. In other words, in terms of protection against cognitive decline, it didn’t matter so much how large your brain was, as long as you stayed active in terms of engaging in leisure activities that involved thinking. In contrast to the findings for BR, CR provided more protection against memory decline than cognitive inefficiency. These results suggest that for MS patients, lifestyle choices, such as engagement in cognitive leisure activities (eg, hobbies, education) appear to provide protection against MS-related cognitive decline independent of the genetically determined factor lifetime brain growth/size.2
Aerobic exercise shown to improvement memory and promote growth of brain tissue
The hippocampus is a part of the brain that is thought to be the center memory and emotion. In fact, in patients with Alzheimer’s disease, a condition associated with a loss of memory, the hippocampus is one of the first regions of the brain to be affected.
MS is often associated with damage to the hippocampus and this damage may occur as soon as 5 years after the disease is first diagnosed. In fact, patients with relapse-remitting MS may have as much as a 10% reduction in the volume of the hippocampus. That means that this crucial part of the brain actually shrinks and loses volume due to the disease process involved in MS. Additionally, half of MS patients suffer from memory impairment, presumably resulting from damage to the hippocampus.
While aerobic exercise has been shown to improve memory and promote the development of nerve tissues in studies conducted in animals, these benefits have not been verified in human patients with impaired brain function.
In an important study presented at this year’s AAN meeting, Leavitt and colleagues conducted a randomized, controlled pilot study (a pilot study is a small test study conducted in a limited number of patients to see if a larger study is warranted) to examine the effect of aerobic exercise on the volume (size) of the hippocampus and memory function in patients with MS who were memory-impaired.3 The study was conducted in two MS patients with memory problems. One patient was randomly assigned to a schedule of non-aerobic exercise involving stretching and the other patient to a schedule of aerobic exercise (stationary bicycling).3
The study showed that aerobic exercise was associated with a 17% increase in the volume of the hippocampus as revealed by MRI compared with little change (3%) for non-aerobic exercise. Additionally, aerobic exercise resulted in a sizable increase in signs of hippocampus functioning while the patient was resting. There was a 54% improvement in memory in the aerobic exercise patient compared with no improvement in the non-aerobic exercise patient. Results from this pilot study provide the first evidence that aerobic exercise results in increases in hippocampus volume and improved hippocampus function. In the study, these increases appeared to result in improvements in memory in the MS patient with memory impairment.3