Multiple sclerosis (MS) is a chronic disease of the central nervous system, affecting the brain, spinal cord, and optic nerves. The immune system mistakenly attacks myelin, the protective covering around nerve fibers, disrupting communication throughout the body. The age when MS first manifests varies widely, spanning from early childhood into late adulthood.
The Typical Age Range for MS Onset
The majority of people diagnosed with MS experience symptom onset during young and middle adulthood, typically between 20 and 50 years old. MS is the most common non-traumatic neurological disorder causing disability in young adults, with the median age for diagnosis clustering around 34 years. Approximately 85% of individuals in this age group initially present with Relapsing-Remitting MS (RRMS), characterized by distinct attacks of neurological symptoms followed by periods of recovery.
Pediatric MS: Diagnosis in Childhood
Multiple sclerosis is rare in individuals under the age of 18, a presentation referred to as pediatric MS (POMS). Only 3% to 5% of all MS cases begin before age 16. Diagnosis requires evidence of damage in multiple central nervous system areas occurring at different times, often needing specialized pediatric neurology expertise. Children with MS almost exclusively present with the relapsing-remitting course. They often experience more frequent relapses than adults during the initial years, but tend to recover more completely and quickly between attacks.
Late-Onset MS: Diagnosis After Age 50
Diagnosis of MS after age 50 is classified as late-onset MS (LOMS), with the average age of onset ranging between 53 and 67 years, and is associated with a different disease course than that seen in younger adults. Individuals with LOMS are more likely to be diagnosed with Primary Progressive MS (PPMS), a form characterized by a steady accumulation of disability from the onset, without clear relapses and remissions. Diagnosis can be challenging because symptoms like fatigue, balance problems, and cognitive changes may be mistaken for normal aging or other neurological conditions. LOMS tends to progress more quickly, with individuals reaching disability milestones faster than those diagnosed earlier.
Risk Factors Influencing Timing
Several factors influence the specific age when MS symptoms first appear. Gender plays a role, as women are diagnosed two to three times more frequently than men overall. However, men who develop MS often experience a later age of onset and are more likely to be in the late-onset group.
While a family history of MS increases genetic risk, it does not dictate the precise age of symptom onset. Environmental factors are also implicated, including low levels of Vitamin D, especially during childhood and adolescence, which are associated with an increased risk of developing MS later in life. Infection with the Epstein-Barr Virus (EBV) appears to be a necessary preceding event, and contracting EBV later in adolescence or adulthood may heighten the risk compared to infection in early childhood.