Drug exposure and the risk of multiple sclerosis: A systematic review

Abstract

The suggestion that some drugs may prevent MS is intriguing and warrants further study. In addition, further pharmacovigilance is needed to assess the safety of anti-TNFα drugs in specific populations in the context of MS risk.

Five years before multiple sclerosis onset: Phenotyping the prodrome

“…While we were unable to find other studies comprehensively investigating all prescriptions filled before MS symptom onset, prior studies have examined specific drugs. 22 Concurring with our observations, a higher use of antidepressants 27 and antibiotics 29 has been reported in people who developed MS compared to controls. Some authors have interpreted changes in drug use in the few years before MS onset or diagnosis as suggestive of these medications altering MS risk.…”

“…Although it remains inconclusive if there is a relationship between antibiotic use and MS risk, it is possible that antibiotic use could change MS risk by altering the gut microbiota. 22 While we cannot exclude the possibility of a causal association between drug exposure and MS risk, we suggest that the prodromal phase must be considered when determining the temporality of an association between any exposure and MS onset.…”

“…Some authors have interpreted changes in drug use in the few years before MS onset or diagnosis as suggestive of these medications altering MS risk. 22 One example is antibiotic use. Although it remains inconclusive if there is a relationship between antibiotic use and MS risk, it is possible that antibiotic use could change MS risk by altering the gut microbiota.…”

“…Previous studies have interpreted such associations as indicating a beneficial effect of pregnancy on MS risk 20,21 or that oral contraceptives may increase MS risk. 22 An alternative explanation is that women who experience a range of unexplained symptoms before MS onset or diagnosis may delay or avoid pregnancy.…”

The Multiple Sclerosis Prodrome: Evidence to Action

“…Studies of other risk factors that have been measured within the presumed prodromal phase, i.e., within 5-10 years of MS symptom onset, include migraines, lower levels of physical activity, diet quality, pregnancy and oral contraceptive use (70-73). Pregnancy, for example, has been associated with a decreased MS risk, while oral contraceptive use associated with an increased risk in some studies (73), but studies of the MS prodromal phase suggest that women who develop MS may choose birth control or delay pregnancy simply because they are experiencing signs and symptoms of the prodromal phase (14). Similarly with diet quality before MS symptom onset, no association with MS risk was found, but if individuals make dietary improvements in response to prodromal sign and symptoms, reverse causation may be one explanation (70).…”