Progression independent of relapse activity (PIRA) has been recently proposed in multiple sclerosis (MS) as a model identifying a continuous silent progression of disability without the manifestation of new clinical and magnetic resonance imaging (MRI) events that contribute to MS worsening. Despite evidence suggesting that clinical MS manifestations often affect cognitive functioning and the importance of neuropsychological monitoring over time, attention to silent cognitive progression is lacking, and the PIRA concept does not include a measure of cognitive function. In this personal viewpoint, we highlight the need to include cognition in the PIRA model to have a more comprehensive understanding of clinical progression in patients with MS.
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