The results of new research investigating a link between physical activity and MND was presented by the University of Sheffield research group in the late-breaking news session on the last day of the 24th International Symposium on ALS/MND. Under the leadership of Prof Pam Shaw, along with Dr Chris McDermott, MND Association-funded researcher Dr Ceryl Harwood presented her findings.
The background of MND and physical activity
Physical activity and the link between MND has long been debated amongst researchers.
There are a number of different types of physical activity; from leisure time (for example an evening walk) to more vigorous physical activity and athleticism (marathon runners and professional sportsmen).
Previous research back in 2008 found that Italians playing professional football had an increased risk of developing MND. However, this research is yet to be confirmed in other countries. Director of Research, Dr Brian Dickie said: “The Italian researchers also looked at professional cyclists and basketball players, but no association was found, so basically the jury has been out on whether athleticism is a risk factor for MND.”
In collaboration with the Medical Research Council (MRC) Epidemiology Unit at Cambridge University Dr Harwood’s project, unlike the previous Italian study, is addressing the question of whether physical activity in adult life in general is a risk factor for MND, extending beyond the focus on professional sportsmen.
Physical activity alone, however, does not cause MND. We already know that MND is an incredibly complex disease, with many factors ‘tipping the balance’ as to whether someone develops it or not. One of these factors alone is therefore not enough to cause MND.
It is likely that physical activity may contribute to a complex interplay between biological and genetic processes, which already predispose an individual to develop MND therefore ‘tipping the balance’
Asking the questions
Gathering the evidence for past physical activity is no easy matter, but Dr Harwood has developed and validated a novel (new) questionnaire to measure physical history in adulthood, using data from a diabetes study in the 1990s where over 1,000 people had detailed measures taken of their actual energy expenditure.
The breaking news!
Dr Harwood made careful measurements of the levels and types of physical activity during adult life in 175 people with MND and 317 control subjects who were matched for age, gender and place of residence. Both during the whole of adult life and in the most recent 15 years, the MND patients had significantly higher levels of total physical activity, vigorous (“working up a sweat”) physical activity and leisure related physical activity compared to the matched control subjects.
This means that this type of physical activity may be a risk factor for MND in these individuals, however further research in other countries is needed to confirm these findings.
This research adds evidence to support the link between MND and leisure time physical activity, however a questionnaire looking at past physical activity will not be 100% accurate. This is because recollections of past physical activity may be limited, hence why further research is needed to support these findings.
Dr Harwood highlighted that she aims to investigate this potential link further by examining gene-environment interactions, identifying susceptibility genes in these individuals. Due to Sheffield’s genetic expertise, Dr Harwood is perfectly placed to delve into the genetic factors that underpin the selective vulnerability of motor neurones.
What this means for people living with MND
Prof Pam Shaw commented on their research: “Many neurologists have long suspected that MND tends to happen to people who fire their motor neurons more than the average person, with high levels of physical activity.
“Clearly most people who are athletic or physically active do not develop damage to the motor system. So we believe that “gene-environment” interaction is at play and that physical activity is only a risk factor in the presence of a certain genetic profile which in turn controls the chemistry within the nervous system.
“The University of Sheffield team are very excited about the results of this study as it has identified, using robust methodology, what appears to be a definite environmental risk factor for the non-inherited form of MND (90-95% of total MND cases). The next steps will be to try to determine the genetic variations, which make some people more susceptible to motor system damage when the lifestyle factor of vigorous physical activity is present. This may eventually allow a preventative approach for MND.”
What other MND researchers are saying
Dr Martin Turner based at the University of Oxford will be holding a meeting in March 2014 looking at athleticism and cardiovascular fitness in MND. Commenting on Dr Harwood’s research in advance of the meeting he said:
“I am particularly looking forward to hearing the Sheffield group’s data on physical activity in MND in the late breaking session. Many MND clinicians notice that their patients tend to be very physically active, generally ‘fitter’ people, before their illness.
“Studies have shown MND patients are typically slimmer than the general population and possibly cardiovascularly fitter, with a different metabolism perhaps. A simple cause-and-effect model between exercise and MND seems too simplistic.
“To try and unravel all of this I am putting together the 1st ‘ACE’ workshop in Oxford next year to bring international experts together to discuss ‘Athleticism, Cardiovascular fitness and Energy metabolism’ in MND. I hope it will help us understand what we are seeing in our patients, with a view to finding ways to identify those at highest risk of MND, as well as novel pathways to the disease and so improved treatment strategies.”
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