One diagnosis, two paths
Multiple sclerosis (MS) is recognized as both an autoimmune and neurodegenerative disorder. In this condition, the immune system mistakenly attacks the myelin sheath surrounding neurons, disrupting nerve signals and leading to a sequence of damaging events. Ultimately, this can result in the loss of axons and neurons, contributing to lasting disabilities.
Healthcare professionals have long noted that MS presents a vast range of symptoms, even among those with the same diagnosis. Some individuals endure frequent inflammatory relapses, while others may experience a more gradual but consistent decline in function. Recent findings imply that these variations reveal two separate trajectories, masked by a singular diagnosis.
Insights from recent research
By utilizing advanced brain MRI techniques alongside a blood marker known as serum neurofilament light chain (sNfL), researchers tracked how damage accumulates in the nervous system. An AI model helped to uncover two distinct patterns that align with clinical and biological data: one characterized by inflammation occurring first, and the other by neurodegeneration taking the lead, each with its own pace of progression.
In the inflammation-first trajectory, inflammatory activity is significant from the outset, with rising sNfL levels accompanying active lesions. Conversely, in the neurodegeneration-first path, the decline in brain volume happens prior to any significant rise in blood biomarkers. These observations substantiate suspicions many neurologists have had, though they struggled to articulate the differences clearly.
“As one neurologist stated, this two-trajectory framework aids us in ‘anticipating the future, at least in a directional way.’”
Differences between the two forms
While these trajectories aren’t rigid categories—people can shift between them—they still provide useful insights for stratifying patients earlier and customizing their care. Differences can often be seen in symptoms, imaging outcomes, and the progression timelines.
- Inflammation-first: frequent early relapses and new lesions on MRI scans enhanced by gadolinium.
- Inflammation-first: quick spikes in sNfL that correspond to inflammatory episodes.
- Neurodegeneration-first: gradual decline in function without significant early relapses.
- Neurodegeneration-first: early brain atrophy, either global or regional, with less noticeable lesions.
- Both trajectories result in cumulative disability reflecting overall tissue loss, not just from relapses.
Importance of the split for treatment
The majority of current treatments for MS are heavily anti-inflammatory, effectively reducing the risk of relapses but falling short in stopping slow axonal loss or repairing damaged myelin. Understanding these differing trajectories earlier might help refine the timing and methods of treatment, moving away from a one-size-fits-all strategy.
For those on the inflammation-first trajectory, quickly moving to high-efficacy therapy might prevent initial damage. Meanwhile, for individuals on the neurodegeneration-first path, focusing sooner on neuroprotective means and trials aimed at remyelination may be necessary. Tailoring clinical trials to these distinct trajectories could enhance the discovery of more effective treatments rather than spreading resources too thinly across mixed populations.
This also allows for clearer guidance to patients, as the short-term risks and long-term objectives differ between the trajectories. For an inflammation-first path, blocking relapses could be the priority. In contrast, the neurodegeneration-first approach would focus more on slowing down unnoticed tissue loss. Ultimately, the goal is to ensure smarter and more durable protection of the central nervous system.
Predictions have limits
While these discoveries hold promise, they shouldn’t be viewed as definitive. sNfL isn’t yet a standard test everywhere, and accurate predictions at the individual level still require thorough validation. The biology of MS is complex; factors like other health issues or life experiences can alter a person’s disease course.
MRI protocols can differ, and the metrics obtained require systematic acquisition and careful analysis. While sNfL indicates overall injury, it doesn’t pinpoint its exact origin, and levels can vary due to infections or other stressors. Truly precise understanding will likely involve a blend of imaging, fluid biomarkers, clinical characteristics, and longitudinal patterns.
Steps for clinicians and patients
Even in the absence of universal biomarker availability, this framework advocates for actionable, evidence-informed measures. The aim is to recognize both acute inflammatory surges and the gradual tissue loss over time.
- Monitor relapse activity and MRI lesion count using consistent protocols.
- Whenever feasible, incorporate quantitative MRI to observe brain atrophy over time.
- Leverage sNfL judiciously where accessible to indicate active injury beyond just inflammation.
- Promptly escalate treatment for clear inflammation-first cases to minimize early damage.
- Consider participation in trials focused on neuroprotection and remyelination for progressive symptoms.
- Combine disease-modifying treatments with lifestyle strategies, such as exercise and good sleep hygiene.
The journey towards personalized MS care
This two-trajectory model reshapes our understanding of MS as one shared diagnosis with diverging paths. It directs research towards targeted goals and encourages earlier, more personalized clinical decisions. By leveraging extensive data from larger cohorts, advanced imaging techniques, and various biomarkers, it could transform pattern recognition into precision care for patients.
In the end, improved stratification has the potential to preserve neural function and help individuals navigate a complicated, evolving disease. By acknowledging MS as both an inflammatory and degenerative process, we can create space for interventions that address both aspects effectively. It’s one condition, indeed—but it manifests in two distinct ways, necessitating tailored, thoughtful responses.
