MS results from the immune system mistakenly attacking the brain and spinal cord and most medications currently available for MS aim to reduce these attacks to prevent further damage. But there is also another component of MS, the loss of brain tissue over time. Brain volume loss or brain atrophy occurs in everyone as we age, but it happens at a faster rate in people with MS. Previous research has also shown that in MS this brain volume loss can be an early feature of the disease and seems to be linked to the accumulation of disability over time, more so than the number of relapses or lesions in the brain.
Due to this link with disability, there is a great deal of interest in this process of brain volume loss. It seems that certain parts of the brain are more susceptible to atrophy than others. And now in new research, led by Dr Arman Eshagi, at the Queen Square MS research group in London, it has been shown that atrophy occurs in a particular sequence.
Dr Eshagi is from Iran and is currently undertaking a McDonald Fellowship from the MS International Federation. These fellowships enable young researchers from emerging countries to work in a research institution outside of their own country. At the conclusion of the fellowship, the researchers return home to use their new skills and networks to enhance research and MS care in their own countries.
Dr Eshagi looked at brain volume loss in people with different types of MS, people with clinically isolated syndrome (a potential precursor of MS) and people without MS. 1424 people took part in the study, which looked at areas of brain volume loss using magnetic resonance imaging (MRI). By looking at the population as a whole, Dr Eshagi was able to determine the areas affected by brain volume loss and for the first time identify the order in which the regions were affected.
Dr Eshagi suspected that the pattern of brain tissue loss would be different for those people who started out with relapsing MS compared with people with primary progressive MS. In fact, the sequence of brain volume loss was reasonably consistent across the different types of MS. Areas of the brain known as the posterior cingulate cortex, precuneus, thalamus and brainstem were affected in early stages of MS irrespective of the type of MS that a person had. The common theme between all these areas is that they are parts of the brain with many nerve connections, perhaps suggesting that these areas that consume a lot of energy and are connected to multiple other areas of the brain may be more vulnerable in MS.
Further analysis of all the people with MS in the study showed that other regions known as insula, accumbens and caudate were also likely to suffer tissue loss early in the disease. This is very interesting as these regions may be part of the brain pathways involved in fatigue and cognition – often the earliest symptoms people report of their MS.
Dr Eshagi also looked at changes to brain volume over time in individuals. He found that the rate of brain volume loss was related to the length of time the person had MS, regardless of the type of MS that they had. In people with relapsing remitting MS, the brain volume loss was independently related to their level of their disability.
This research is a great advance for the understanding of MS. While this research study represents only the first step, future research into this area may create the possibility categorising an individual’s “stage” of brain volume loss. This could help identify groups of people that may benefit from particular types of therapies based on their stage of disease or identify people for clinical trials. This would lead to better and more meaningful clinical trial results and eventually could be used to identify windows of opportunity for treatment decisions for people with MS in the clinic.