Barts-MS rose-tinted-odometer – zero stars
Someone recently asked what is advanced MS? I suspect they have been getting frustrated with our use of this adjective without a clearer understanding of what it really means. To find out if you have advanced MS you need to put yourself through a battery of stress tests to find-out much reserve you have left to deal with MS and life in the future.
What is advanced MS is a very important topic and we at Barts-MS have tried not to define it using the EDSS as it entrenches the physically-disabling, particularly lower-limb function, worldview of MS.
Advanced MS is really when someone has lost reserve in a particular neuronal system and they are noticing worsening in that system that is impacting on their ability to function at a personal, social or occupational level and by inference is affecting their quality of life.
Using this definition someone can have advanced MS with very little physical disability. As you are aware the initial impact of MS may be cognitive, which is probably the main driver of the high early unemployment rates we see in MS.
A software engineer with MS who depends on her cognitive skills for writing code, concentrating for prolonged periods of time and multitasking may find it very difficult-staying at the top of her game. She will notice much earlier her progressive cognitive loss based on her performance or lack of performance in her work. In comparison, a professional athlete may not necessarily notice early cognitive impairment but will be more susceptible to the effects of MS on their coordination and endurance, for example, the marathon runner with a dropped foot.
These examples are the two extremes, but they illustrate why we need stress tests of the nervous system to be able to ascertain how much reserve there is which will give us some idea how advanced MS is in a particular domain. One thing that is not done very well in MS clinics is cognition. Most MS centres don’t have the resources to monitor cognition properly. This needs to change (#ThinkCognition).
In almost every MS clinic I do I see patients who complain of cognitive symptoms; increasing forgetfulness, difficulty multi-tasking, the inability to learn and use a new technology or cognitive fatigue.
One of my high functioning patients, who worked in a large City law firm, simply could not keep up and was forced to take early retirement because of her MS. She had been interferon-beta-1b for 12 years but had stopped treatment about 7 years ago when she had moved to London. Her MRI showed a highish lesion load and severe brain atrophy. She had had a few relapses on interferon-beta in the early years, but her neurologist decided to leave her on interferon-beta. Back then this was normal practice; we didn’t expect interferon-beta to render you relapse-free. Interferons were only meant to reduced attack rates by about a third and severe attacks, i.e. those requiring steroids and/or hospital admission, by about a half. The only alternative when this patient was having relapses on interferon-beta was glatiramer acetate; this was in the pre-natalizumab era.
Apart from her cognitive problems, this patient had mild unsteadiness of gait, but this had not affected her walking distance and she was still able to do yoga several times per week. To help with her unemployment insurance claim I requested a formal neuropsychological assessment and she was documented to have profound cognitive deficits across multiple domains. The conclusion based on these tests was that she would never be able to have meaningful employment again; at least not in the knowledge economy When I took a detailed history it was clear that she had had progressive cognitive impairment over at least 7-10 years. In other words, she had advanced (secondary progressive) MS manifesting as progressive dementia.
You must not underestimate the impact MS has on cognition. Cognitive problems can be there from the start; approximately a quarter of people with a radiologically isolated syndrome (RIS) or asymptomatic MS already have cognitive impairment. The proportion with cognitive impairment gets higher the longer you have the disease. What is driving cognitive impairment is almost certainly grey matter pathology, both in the cortex and deep grey matter, which is not detected with our current monitoring tools.
Until recently we the MS community used the Paced Auditory Serial Addition Test (PASAT) for monitoring cognition in clinical trials. The PASAT is a measure of cognitive function that assesses auditory information processing speed and flexibility, as well as calculation ability. The PASAT is presented using audiotape or disk to ensure standardization in the rate of stimulus presentation. Single digits are presented every 3 seconds and you have to add each new digit to the one immediately prior to it. Shorter inter-stimulus intervals, e.g., 2 seconds or less have also been used with the PASAT but tend to increase the difficulty of the task. The PASAT is very difficult and requires multitasking; it is a very good cognitive stress test.
One of the reasons we dropped the PASAT test is because of its learning effect, when you do the PASAT test your scores improve because of so-called ‘learning’ or ‘practice’ effects. In reality this is a general phenomenon of most neurological stress tests; our nervous systems are wired for learning.
In the FREEDOMS 1 and 2 pivotal phase 3 fingolimod trials, we showed that not being able to improve on the PASAT at baseline predicted a worse outcome. We hypothesised that pwMS who couldn’t learn, i.e. were unable to improve their PASAT scores at baseline, would do worse and this is exactly what we found and we noted it regardless of treatment allocation; i.e. whether you were on fingolimod or placebo.
Not surprisingly, the poor learners were older, had a higher disability score at baseline, smaller brains and higher lesions volumes on MRI; i.e. they had reduced cognitive reserve or resilience. In other words, they had more advanced MS. The depressing point about this analysis was that even the poor learners on fingolimod did badly; it was if they were already primed to do badly and that starting a DMT had a limited impact on the outcome. In reality, their MS disease activity in the past had primed their brains to continue to deteriorate despite being on a DMT; previous damage or smouldering MS was now driving their disease worsening. This is why the treatment response on DMTs drop off with ageing and disease duration. Please note this applies to all DMTs, including HSCT.
It is important to prevent the ravages of MS by treating as early and effectively as possible. Some pwMS are luckier than others; i.e. you may present very early in the course of your MS before too much end-organ damage has accrued. In others, the asymptomatic period of the disease may be longer, during which time you acquire a lot of end-organ damage. Regardless of what group you are in, you still need to seriously consider getting on top of your MS disease activity as soon as possible to prevent any further damage.
It is clear from several data sources that on average pwMS do best on DMTs that have the greatest impact on inflammatory activity (new MRI lesions and relapses) and those that reduce brain volume loss. In reality, these are the high and very high efficacy DMTs. This is why flipping the pyramid and going for the most effective DMTs first-line is a very appealing treatment strategy; particularly the DMTs that ‘normalise’ brain volume loss.
This post illustrates why we should be monitoring cognition in routine MS clinical practice. Although this topic gets discussed and debated all the time most neurologists don’t agree with doing routine cognitive testing, because of the lack of evidence in terms of treatments that impact on cognition. This, however, will change as data emerges that DMTs have positive effects on cognitive function, even in advanced MS. For example, siponimod has been shown to delay cognitive worsening compared to placebo in people with SPMS.
At Barts-MS we will continue to run our #ThinkCogniton campaign. By shifting the MS worldview from a physical one to a cognitive one we will hopefully get the MS community to manage MS more actively.
Maria Pia Sormani et al. Learning Ability Correlates With Brain Atrophy and Disability Progression in RRMS. J Neurol Neurosurg Psychiatry, 90 (1), 38-43 Jan 2019.
Objective: To assess the prognostic value of practice effect on Paced Auditory Serial Addition Test (PASAT) in multiple sclerosis.
Methods: We compared screening (day -14) and baseline (day 0) PASAT scores of 1009 patients from the FTY720 Research Evaluating Effects of Daily Oral therapy in Multiple Sclerosis (FREEDOMS) trial. We grouped patients into high and low learners if their PASAT score change was above or below the median change in their screening PASAT quartile group. We used Wilcoxon test to compare baseline disease characteristics between high and low learners, and multiple regression models to assess the respective impact of learning ability, baseline normalised brain volume and treatment on brain volume loss and 6-month confirmed disability progression over 2 years.
Results: The mean PASAT score at screening was 45.38, increasing on average by 3.18 from day -14 to day 0. High learners were younger (p=0.003), had lower Expanded Disability Status Scale score (p=0.031), higher brain volume (p<0.001) and lower T2 lesion volume (p=0.009) at baseline. Learning status was not significantly associated with disability progression (HR=0.953, p=0.779), when adjusting for baseline normalised brain volume, screening PASAT score and treatment arm. However, the effect of fingolimod on disability progression was more pronounced in high learners (HR=0.396, p<0.001) than in low learners (HR=0.798, p=0.351; p for interaction=0.05). Brain volume loss at month 24 tended to be higher in low learners (0.17%, p=0.058), after adjusting for the same covariates.
Conclusions: Short-term practice effects on PASAT are related to brain volume, disease severity and age and have clinically meaningful prognostic implications. High learners benefited more from fingolimod treatment.