Age at Relapsing-Remitting Multiple Sclerosis Onset Increases in Over 50 Years

The age of disease onset for patients diagnosed with relapsing-remitting multiple sclerosis (RRMS) has increased over the past 50 years, according to study findings published in Multiple Sclerosis and Related Disorders.

Most patients with RRMS, the most common form of MS, are diagnosed between the ages of 20 or 40, but the disease can develop at any age. Previous research has provided preliminary evidence that the age of MS onset has increased over the past decades. Now, researchers of the current study sought to verify whether this trend is real.

The researchers conducted a cohort study of 1622 patients (67.6% female) experiencing their first symptoms of RRMS who were seen at the MS clinic of Bellvitge University Hospital in Spain between January 1970 and December 2019. The researchers divided patients into 5 subgroups according to the decade when their RRMS symptoms began — 1970-1979, 1980-1989, 1990-1999, 2000-2009, and 2010-2019.  

The mean age of RRMS onset for the entire cohort was 31.11±9.82 years. After analyzing the mean age of RRMS during each of the 5 decades, the researched observed the significant trend of a gradually increasing age of onset (P <.001). The mean ages at onset were:

• 23.79±10.19 years in the 1970s
• 27.86±9.22 years in the 1980s
• 30.07±9.32 years in the 1990s
• 32.12±9.47 from 2000-2009
• 34.28 ± 9.83 years from 2010-2019

Of the 1622 patients, 5.9% had early-onset MS (before age 18) and 4% had late-onset MS (after age 50). The researchers noted that the incidence of patients with early-onset MS decreased over time, while the incidence for late-onset MS continued to increase. However, differences in the ages at onset remained significant even after these 2 groups were excluded.

“Changes in diagnostic criteria may have contributed to the reported increase in the incidence of MS as well as the increase in age at disease onset,” the researchers speculated.

“Another potential reason for the higher age at onset in recent decades could be the aging of the general population in [this] area…Increase in outdoor activities over time as well as the adoption of sunbathing could potentially explain the older age at which the first symptoms manifest,” they added.

Possible follow-up, recall, and referral biases as well as delays between symptom onset and actual diagnosis may have limited or impacted study results.

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.