Greater disability tied to poorer cognitive function in people with RRMS

In people with relapsing-remitting multiple sclerosis (RRMS), greater physical disability is associated with poorer cognitive function, while higher levels of formal education are linked to better cognitive performance, a new study found.

The findings highlight the relationship between physical and cognitive symptoms of MS, even among people with mild to moderate physical disability, and support an association between higher education and better cognitive performance in people with RRMS.

In contrast, markers of oxidative stress, a biological process that can lead to cell damage and has been implicated in multiple sclerosis (MS), showed limited and inconsistent associations with measures of symptom severity.

The study, “Oxidative stress, depressive symptoms, disability, cognitive outcomes and hand dexterity in relapsing-remitting multiple sclerosis patients with mild/moderate disability,” was published in IBRO Neuroscience Reports.

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Cognitive problems can emerge despite mild physical disability

Cognitive problems are common in MS and can affect memory, attention, information-processing speed, and other abilities. They can occur even when physical symptoms are relatively mild, potentially affecting daily activities and quality of life.

Oxidative stress occurs when reactive molecules produced during normal cellular processes overwhelm the body’s antioxidant defenses, potentially damaging components of cells. This type of damage has been implicated in the development of MS and other neurological diseases, leading many researchers to speculate whether these diseases might be treated with antioxidants (molecules that reduce oxidative stress).

However, it hasn’t been clear whether oxidative stress markers are associated with the severity of cognitive and physical MS symptoms.

In this study, scientists in Iran analyzed data from 83 adults with RRMS, all with mild to moderate physical disability. The researchers assessed physical disability, cognitive function, depressive symptoms, and hand dexterity. They also measured six markers of oxidative stress in blood samples to determine whether these markers were associated with the severity of MS symptoms.

The analyses showed that poorer cognitive performance was associated with greater physical disability, suggesting that these symptoms of MS often go hand-in-hand.

In contrast, participants with more formal education generally had better cognitive scores, a finding the researchers said aligns with the cognitive reserve theory — the idea that greater lifelong cognitive stimulation may help some people better withstand disease-related brain changes and maintain cognitive abilities.

“Education emerged as a strong protective factors for cognitive dysfunction, consistent with cognitive reserve theory, the capacity to maintain cognitive performance through compensatory neural mechanisms,” the researchers wrote.

Meanwhile, the oxidative stress markers showed limited and inconsistent associations with cognitive outcomes and measures of physical disability.

“The absence of independent associations between peripheral oxidative stress markers and cognitive or disability outcomes in the present study suggests that circulating oxidative stress biomarkers should not be considered reliable surrogate markers for selecting patients or monitoring the response to antioxidant-based interventions, particularly in early-stage of RRMS,” the researchers concluded.

A notable limitation of this study is that patients were assessed at a single point in time. The researchers called for further work to evaluate how oxidative stress markers and cognitive function change over time and whether those changes are related.