The controversial diagnosis of benign MS (BMS) has been further confounded by evidence that cognitive impairment, fatigue and depression are common yet currently not considered in an EDSS-based definition.
An Australian-led study comprised 786 consecutive US patients with MS – 141 people with BMS defined as an EDSS score of 3 or lower combined with a disease duration 10 years or longer, 158 people with a comparable disease duration but not classified as BMS and 487 people with a shorter duration of MS.
A comprehensive neuropsychological assessment found the rate of cognitive impairment was 43% overall – 37.6% in people with BMS compared to 65.3% in people with non-BMS (p< 0.001) and 37.5% in the shorter duration of MS subgroup (p-0.998).
The study, published in Multiple Sclerosis and Related Disorders [link here], found no significant difference in scores between people with BMS and people with non-BMS on the subtests of Visual Spatial and Verbal Function.
However in five of the seven subtests (Memory, Executive Function, Attention, Information Processing and Motor Skills), people with non-BMS scored significantly lower than the people with BMS.
The study found fatigue (77.7%) on the Fatigue Severity Scale and depression (55%) on Beck’s Depression Inventory were common and clinically relevant findings in people with BMS.
Fatigue was lower in people with BMS than those with similar duration of non-BMS disease while other comparisons showed no significant differences.
The investigators, led by Dr Hans Bogaardt from the University of Adelaide, said the ‘invisible’ symptoms of cognitive impairment, fatigue and depression were clearly common in people with BMS.
“The unrecognised impact is even more concerning considering the lack of routine multi-domain cognitive monitoring in the management of people with MS and the sub-optimal clinical validity of current screening tools for cognitive function, like the SDMT [Symbol Digit Modalities Test].”
They said their findings “contribute further evidence to the discussion surrounding the classification of this condition as “benign”.
“The high rate of cognitive impairment, depression and fatigue in people with BMS found in this study raises the question how people with BMS are coping in everyday life, and how the rate of 38% of cognitive impairment in this group would reflect on their employability, their social life and their partners.”
They said multi-domain cognitive testing in routine MS care would be helpful.
“Further research is also needed into how people with ‘benign’ MS have currently access to health services and how their needs are supported.”