Late-onset multiple sclerosis (LOMS) is defined as symptoms initiating at an age above 50.
This study aims to determine the clinical and epidemiological aspects of LOMS in East-Azerbaijan province, Iran.
This population-based study recruited nearly all MS patients to the end of 2020, who were diagnosed at age≥50, by referring to the only local MS registry center. We investigated prevalence, sex, age-of-onset, first clinical presentation, family history, and gap of diagnosis. Also, we compared the disease characteristics between male and female cases.
Out of 4905 total cases of MS, 217 cases (4.42%) were LOMS. The mean age of onset was 53.80±3.41 years with a maximum age of 68 years. The most common age group of the patients was 50 to 55 years (69.1%). The frequency by sex of LOMS in females (150) was greater than males (67). Positive family history was seen in 6.17%, and in 41% of the patients, the disease was diagnosed in a timely manner. Early symptoms were motor (31.3%), sensory (24.8%), optic neuritis (23%), cerebellar symptoms (13.8%), and brainstem symptoms (6.9%). The first presentation of the disease was different between male and female cases (-value<0.01). Motor symptoms were the most prevalent first clinical presentation in female cases (37.6%), while in male cases, cerebellar symptoms (25.8%) were the most common.
LOMS is not a rare condition. Increasing knowledge in the diagnosis, as well as increasing awareness of the disease in the general population, leads to early diagnosis of LOMS and prevention of consequences.

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