- This study looked at data from an online MS registry (MSBase); 9811 patients at 55 centers had relapses within the start of the observation period
- There was an annual pattern to relapse onset: they were most common in spring, and least common in fall. Less time elapsed between the winter nadir of solar radiation and the spring peak of relapses at higher latitudes
- The article speculates this is because residents of more northern latitudes have lower reserves of vitamin D, but it also points out that some respiratory viruses follow this pattern as well
Still unclear, I guess, but this is good support there is a seasonal effect.