Age distribution of progressive multifocal leukoencephalopathy

Area of Science:

• Neuroscience
• Virology
• Epidemiology

Background:

• Progressive multifocal leukoencephalopathy (PML) is a rare, demyelinating disease of the central nervous system.
• PML is caused by the JC virus, a ubiquitous virus that typically infects individuals in childhood.
• The age distribution of PML cases is not well-characterized, particularly in comparison to other neurological diseases.

Purpose of the Study:

• To determine the age distribution of progressive multifocal leukoencephalopathy (PML) cases.
• To compare the age distribution of PML with multiple sclerosis (MS) and viral encephalitis.
• To explore potential reasons for the late onset of PML despite childhood JC virus infection.

Main Methods:

• Analysis of age distribution data from 79 confirmed PML cases.
• Comparison with published age distribution data for MS onset in Norway.
• Comparison with published age distribution data for viral encephalitis in Rochester, Minnesota.

Main Results:

• PML predominantly affects adults, with a peak incidence in the sixth decade of life.
• In contrast to viral encephalitis (61% in children <10 years), PML was identified only once in this age group.
• PML exhibits an adult onset pattern similar to multiple sclerosis.

Conclusions:

• PML is a disease of adult onset, distinct from viral encephalitis which commonly affects children.
• The late onset of PML, despite ubiquitous childhood JC virus infection, remains uncertain.
• Potential factors for late onset include brain cell maturation and age-related or chronic disease-associated immune decline.