possibly not significantp = 0.344
A statistically significant correlation of sGFAP levels and age ( Figure 5 ) was only seen in SPG4 patients (Spearman’s ρ = 0.554, p = 0.004), whereas it was absent in PPMS (possibly not significant due to the higher variability; Spearman’s ρ = 0.198, p = 0.344) and controls (Spearman’s ρ = 0.213, p = 0.103).