Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2015;132(199):29-36.
doi: 10.1111/ane.12428.

Time trends in the incidence and prevalence of multiple sclerosis in Norway during eight decades

N Grytten  1   2 , Ø Torkildsen  1   2 , K-M Myhr  1   3
Affiliations
Review

Time trends in the incidence and prevalence of multiple sclerosis in Norway during eight decades

N Grytten et al. Acta Neurol Scand. 2015.

Abstract

Norway has been subjected to numerous epidemiological investigations on the prevalence and incidence of multiple sclerosis (MS), dating back to 1935. The objective of this study was to review the studies on the prevalence and incidence of MS in Norway, provide an update on the prevalence of MS in Norway, and describe the time trends in the prevalence and incidence of MS in relation to risk factors, case ascertainment, and data. We performed a systematic search on PubMed and MEDLINE up to November 2014 using the search string 'multiple sclerosis prevalence in Norway' or 'multiple sclerosis incidence in Norway'. In addition, we scrutinized the reference lists of the publications identified for relevant citations. We retrieved data on the distribution of MS in Norway on December 31, 2013 from the Norwegian Multiple Sclerosis Registry and Biobank and the Norwegian Patient Registry. We identified 29 articles. From 1961 to 2014, the reported prevalence of MS increased from 20 to 203 per 100,000 inhabitants, and the incidence increased from 1.9 to 8.0 per 100,000. The nationwide crude prevalence in Norway, based on the Norwegian Patient Registry, was 208 per 100,000 on December 31, 2013. The reported prevalence of MS in Norway has increased 10-fold, with several possible causes. During eight decades, neurological health services have generally become more accessible to the population, and transforming diagnostic criteria has made the diagnosis of MS more precise and valid. There have also been changes in lifestyle behavior and known risk factors, such as vitamin D and smoking, that might have contributed to the increased incidence of MS. A possible role of increased survival in MS needs to be examined further.

Keywords: environmental risk factors; incidence; multiple sclerosis; prevalence; time trends.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Counties in Norway.
Figure 2
Figure 2
(A) Time trends in prevalence and diagnostic criteria of multiple sclerosis (MS) in Norway during 1961–2014, with 95% CI where available. The year on x-axis refers to the prevalence year and not the publication year of the study. (B) Time trends in incidence and diagnostic criteria of MS in Norway during 1961–2007, with 95% CI where available. The year on x-axis refers to the prevalence year and not the publication year of the study.
See this image and copyright information in PMC

Comment in

References

    1. Simpson S, Jr, Taylor BV. The Scandinavian paradox revisited: editorial comment on Berg-Hansen et al. ‘High prevalence and no latitude gradient of multiple sclerosis in Norway’. Mult Scler. 2014;20:1675–7. - PubMed
    1. Swank RL, Lerstad O, Strom A, Backer J. Multiple sclerosis in rural Norway its geographic and occupational incidence in relation to nutrition. N Engl J Med. 1952;246:722–8. - PubMed
    1. Westlund K. Recent statistical data on multiple sclerosis and some other diseases in Norway. Nordic Council Arctic Med Res Rep. 1982;32:19–29.
    1. Westlund K. Distribution and mortality time trend of multiple sclerosis and some other diseases in Norway. Acta Neurol Scand. 1970;46:455–83. - PubMed
    1. Berg-Hansen P, Moen S, Harbo H, Celius E. High prevalence and no latitude gradient of multiple sclerosis in Norway. Mult Scler. 2014;20:1780–2. - PubMed