Psychiatric symptoms such as mood and anxiety disorders are common in the years leading up to multiple sclerosis (MS) onset and could be a feature of the MS prodrome, a case–control study from British Columbia, Canada reveals. In the 5 years before the index event, defined as the first demyelinating disease-related claim or MS symptom onset, patients with MS showed a higher prevalence of psychiatric symptoms than did matched control individuals, and the difference between these two groups widened as the index event approached.