Figure 2: Correlations in activity fluctuations at baseline and during the follow-up assessments.

(A) Correlations at time scales <2 hours, as characterized by the DFA exponent α1, decreased gradually over time. (B) Correlations at time scales >2 hours, as characterized by the DFA exponent α2, remained virtually unchanged over the period of the study. For better visualization, data during the follow-up assessments were divided into three bins (<6 months, 6–12 months, and >12 months). P values for the influences of time on the exponents were obtained using mixed models in which time into the study was included as a continuous variable (i.e., not binned categorized variable). Mean values were obtained from all individuals in all groups and error bars indicate standard errors (between individuals).