Late-onset multiple sclerosis

OBJECTIVE: The onset of multiple sclerosis (MS) after age 50 is infrequent and presents a diagnostic challenge. The purpose of the present study was to review the prevalence, presentation, and clinical characteristics of late-onset MS. DESIGN: A retrospective chart review. SETTING: The Multiple Sclerosis Center at Sheba Medical Center, Israel. PARTICIPANTS: 640 patients with a definite diagnosis of MS. MEASUREMENTS: Diagnosis of MS was established according to Poser criteria and confirmed by brain magnetic resonance imaging (MRI) using our unit's computerized database. Late-onset MS was defined as the first presentation of clinical symptoms after the age of 50 years. For each patient, age, gender, clinical presentation, disease course, neurological involvement, disease duration, neurological disability assessed, and Progression Index (PI) were analyzed. All patients were interviewed using the structured clinical interview for DSM-IV, SCID-lifetime Hebrew version. RESULTS: Of 640 MS patients, 30 (4.6%) were diagnosed as suffering from late-onset MS. Mean age at onset was 53.5 +/- 3.1, range 50 to 62 years. Female to male ratio was 1.73:1. Mean disease duration was 7.6 years, range 2 to 11 years. In 50% of patients the disease course was relapsing-remitting. Motor symptoms were the most common neurological presentation at onset (63.3%). Major depressive episode was diagnosed in 6 out of 30 patients (20%) in the two years prior to the diagnosis of MS. After a mean disease duration of 7.6 years there was a marked increase in sphincteric and cerebellar involvement. In addition 7 out of 30 patients had suffered a major depressive episode within 4 years of diagnosis. Mean PI was 0.81, suggesting rapid neurological deterioration. CONCLUSIONS: Late-onset MS is not rare and may present as major depression and, although neurological presentation at onset is similar to that of young adults, progression to disability is more rapid and a primary progressive course is more prevalent.