13 msfocusmagazine.org on the prior 12 months). A major pointofthenewwayofclassifying the disease is to distinguish worsening because of relapses from worsening because of progressive disease. The term “progression” is now to be used only in context of worsening disability in progressive MS (independent from relapses). Is PPMS worse than RRMS? While MS is different for every person, there are several factors that may give some insight into how it is likely to progress. These prognostic factors have been examined in several studies, providing two key insights: • Your first symptoms may indicate how rapidlyyour disease progresses. The London Ontario cohort study suggested that patients whose disease manifests with multiple problems simultaneously (such as visual symptoms, balance, weakness, etc.) at the onset might develop a more rapid disease progression. The British Columbia study reported that sensory symptoms alone at onset were associated with a slower time to progression of disability. • Yourage at onset might influence progression as well. Younger age at onset was associated with a slowertime to reach disability.Another study has examined prognostic factors over a wider time interval, and found that age at onset was the only factor consistently associatedwith time to disabilityprogression. However, sex and cerebellar symptoms (balance, coordination) at disease onset wereassociatedwithtimetoselecteddisability milestones, suggesting that even if age is a key factor, some other factors may exert a variable influence over specific periods of the disease course. These factors have important implications as they might influence therapeutic strategies. But regardless of the symptoms at onset and age at presentations, it seems that people with PPMS might accumulate disabilityfasterthan RRMS. There have only been a small number of studies following patients from diagnosis onward. But the mean times to reach disability milestones have been similar across these studies, and the finding of PPMS patients accumulating disease more rapidly than relapsing onset patients has been universally replicated in all studies. Is primary progressive MS a different disease than relapsing MS? This is perhaps the most challenging question to answer. It has been a subject of speculation and debate for many years. Despite early uncertainty about this topic, recent evidence points towards all forms of MS sharing common disease mechanisms. ThevarioustypesofMSmightsimplyrepresent a spectrum of clinical manifestations ranging from relapsing disease with little accumulated disability in the interim, to PPMS where disability accumulates irrespective of relapses, which are relatively unusual. A recent international genome-wide association study found no genetic difference between PPMS and relapsing-onset disease. Pathological studies have also shown no differences between the lesions seen in different clinical With the new designations, all MS types are now classified as either “active” or “inactive”, and “progressive” or “non-progressive.”