This is potentially consistent with NfL levels peaking prior to the onset of appreciable clinical features.35 Our observation of higher baseline NfL levels predicting more rapid motor and functional progression as well as the development of postural instability mirrors several other studies.14–17 36 Despite only noting a trend towards baseline NfL levels being associated with cognitive progression as determined by changes in the MOCA, we noted a significant predictive capacity for earlier development of dementia. This evidence concerns the gene NEFL and dementia.