Twin study of multiple sclerosis: an epidemiologic inquiry

Area of Science:

• Neurology
• Epidemiology
• Twin Studies

Background:

• The National Research Council Twin Registry includes 16,000 pairs of white male twins with military service.
• Twin registries are valuable for studying genetic and environmental influences on disease.
• Multiple Sclerosis (MS) is a complex neurological disease with suspected environmental contributions.

Purpose of the Study:

• To investigate the prevalence of multiple sclerosis (MS) in a cohort of male twins.
• To explore potential environmental factors associated with MS onset in twin pairs.

Main Methods:

• Analysis of military and Veterans Administration records and questionnaire data from 16,000 twin pairs.
• Identification of MS cases and examination of environmental exposures in affected individuals and their co-twins.
• Comparison of environmental events (trauma, infection, allergy, etc.) in the 20 years preceding MS onset.

Main Results:

• An age-specific prevalence rate of 51 per 100,000 veterans aged 43-53 was observed, approximately half the expected frequency.
• Among affected twins, there was a higher incidence of trauma, operations, ether anesthesia, allergy, infection, and animal exposure compared to unaffected co-twins.
• The frequency of these environmental events increased progressively in the 20 years leading up to MS onset.

Conclusions:

• The observed MS prevalence in this twin cohort was lower than expected.
• Environmental factors, particularly infections, trauma, and allergies, appear to play a significant role in the development of MS.
• Further research into specific environmental triggers and their timing relative to MS onset is warranted.