Multiple sclerosis (MS), the most common cause of neurologic disability in young adults, is an inflammatory disorder of the brain and spinal cord with potentially disabling symptoms that vary between MS patients. The underlying cause is demyelination, the destruction of the protective sheath that covers nerve fibers. Eventually, this can lead to damage and deterioration of the nerves with concomitant symptoms.
There are a wide spectrum of MS neurological symptoms with internal organ dysfunction, visual, motor, and sensory problems being the most common. Some severe MS patients may lose the ability to walk. The majority of people with MS experience long periods of remission without any new symptoms, however some can have a continuous, but gradual, decline in neurological function.
The exact cause of MS is unknown, however as with any disease it is likely to involve an interplay between genetic and environmental factors such as infectious agents. A new study with senior author Rune Midgard of the Norwegian University of Science and Technology, estimated the MS prevalence and incidence trends in Møre and Romsdal County, Western Norway, encompassing 70 years of surveillance. The data was obtained from the Norwegian Multiple Sclerosis Registry and Biobank and the results published in the journal Neurology Neuroimmunology & Neuroinflammation.
Adjusted MS prevalence was found to be 356.6 per 100,000 of the World Health Organization (WHO) standard population. The prevalence rate was 2.3x higher in women compared to men. Incidence has increased dramatically over time, however this could be due to greater awareness of the disease, both amongst medical doctors and the community at large. Environmental changes could also have played a role, however this remains to be investigated.
The study is limited by retrospective design, and changing diagnostic criteria over the 70 year period of analysis.
“In this study, we show a high point prevalence and increasing incidence of MS in Møre and Romsdal County in Western Norway through almost 7 decades. Improved diagnostic tools, temporal changes in diagnostic criteria, increased public awareness, access to disease-modifying therapies, and increased survival among patients due to improved symptomatic treatment and prevention of complications are likely contributing factors that in part could explain the observed incline in MS incidence and prevalence, but changes in environmental risk factors during almost 70 years might also play a role. Further studies should seek to elucidate the underlying mechanisms responsible for the observed changes,” concluded the authors.