This important finding suggests that simple lifestyle modifications, such as diet and exercise, may slow the rate of disability progression in MS because these changes will help to reduce the levels of ‘bad’ fats that are circulating in the body.
The researchers, led by Dr Ingrid van der Mei at the Menzies Institute for Medical Research, have published their findings in two papers published in the Multiple Sclerosis Journal and the Journal of the Neurological Sciences.
Dr van der Mei received an MS Research Australia project grant in 2012 to investigate whether fats play a role in the risk of relapses in MS and disability progression.
Fats are an essential component of the brain and contribute to its repair and maintenance. There is now international evidence suggesting that some fats, such as particular types of cholesterol and triglycerides, usually associated with poor cardiovascular health, are associated with the onset and progression of MS.
In the current project, PhD student Mr Prudence Tettey, working with Dr van der Mei, has examined the fat profiles of 141 people with relapsing remitting MS, in blood samples that were collected every six months over a two and a half year period. This work is part of the National Health and Medical Research Council-funded Tasmanian MS Longitudinal Study. This study is a highly valuable long-term data resource with detailed information on relapses, disability, MRI scans, lifestyle, immune function, virology and genetics.
They found that the amounts of a number of different fats in the blood, including the high and low density lipoproteins (HDL and LDL), and triglycerides, were closely associated with disability level as measured by the Expanded Disability Status Score (EDSS). This association remained strong even when other potentially confounding factors such as smoking, exercise, age and sex were taken into account.
The yearly change in the disability level of each patient was also assessed in relation to fat levels over the period of the study. This indicated that a higher rate of disability progression was also associated with higher levels of total cholesterol (TC) relative to HDL levels (that is a higher TC/HDL ratio).
However, fat levels did not have any influence on the risk of experiencing a relapse for the people in the study and body mass index (a measure calculated from weight and height to determine obesity levels) was also not related to relapses.
This suggests that rather than influencing the inflammatory processes that underlie relapses in MS, the profile of fats in the blood may instead influence the ongoing degeneration of brain tissue that drives the progressive phase of the disease.
The researchers looked at the levels of physical activity and used time-lag modelling of the data, but could find no evidence for ‘reverse causality’ i.e. that a faster progression in disability leads to a higher body mass index (BMI) and higher fat levels in the blood.
The authors suggest that reducing fat levels in the blood, decreasing BMI into the healthy range, and increasing physical activity may significantly reduce the accumulation of disability for people with MS. They recommend that clinical studies are required to confirm the benefits of these types of interventions for slowing disability progression over time.