Multiple System Atrophy

Epidemiology and Etiology

MSA occurs more commonly in men than women (approximately 1.3:1). Onset is typically in the 6th decade, and survival is approximately 6-9 years after diagnosis.

A study of incidence MSA indicated there are 3 new cases per 100,000 person-years in those between ages 50 and 99. There were no cases with onset younger than age 50 in this study. Prevalence studies suggest there are 2 to 5 cases per 100,000 people.

There are no known genetic causes of MSA, and no familial pattern suggesting a strong genetic contribution to the disease. Inherited cerebellar degenerations are sometimes mistaken for MSA, but genetic investigations can often differentiate the two.

Environmental factors have been implicated in MSA. Specifically, risk is increased from occupational history of farming, and decreased with smoking.