Shift work at young age is associated with increased risk for multiple sclerosis.

Area of Science:

• Neuroepidemiology
• Environmental Health
• Chronobiology

Background:

• Environmental factors are significant in multiple sclerosis (MS) etiology.
• The link between shift work and MS risk has not been previously explored.

Purpose of the Study:

• To investigate the potential association between shift work and the risk of developing multiple sclerosis (MS).

Main Methods:

• Two population-based case-control studies were utilized, one with incident cases (1,343 cases, 2,900 controls) and one with prevalent cases (5,129 cases, 4,509 controls).
• Logistic regression analysis was employed to compare MS occurrence in subjects exposed to shift work versus those never exposed, calculating odds ratios (OR) with 95% confidence intervals (CI).

Main Results:

• A significant association was found between early-life shift work and MS occurrence in both studies (OR 1.6; 95% CI 1.2-2.1 and OR 1.3; 95% CI 1.0-1.6).
• Individuals working shifts for ≥3 years before age 20 showed a doubled risk of MS (OR 2.0-2.1; 95% CI 1.2-3.6 and 1.3-3.4).

Conclusions:

• The consistent association in two independent studies supports a true relationship between early shift work and MS.
• Potential mechanisms include circadian disruption and sleep restriction, leading to altered melatonin secretion and inflammation.