Fig. 1

An illustration of early warning signals in one individual (ID6) in the item “I feel extremely well”. A depicts weekly manic (Altman Self-Rating Scale, ASRM, blue) and depressive (Quick Inventory of Depressive Symptomatology, QIDS-SR, red) symptom scores. At week 8 and 15, she reports an abrupt transition to a manic and depressive episode, respectively. Figure 1B visualizes her raw ecological momentary assessment (EMA) scores on “feeling extremely well”. Higher scores indicate she is feeling more euphoric. We iteratively fitted windows containing two weeks of observations (green rectangles). These windows slided through the time series, meaning that the first window contained observations 1–70, the second window contained observations 2–71, etc. Note that the windows in the figure solely serve to illustrate the main idea behind the analyses. Within each window, we computed the autocorrelation and standard deviation as early warning signals (EWS). This yielded surrogate time series of the autocorrelation and standard deviation. As shown in Fig. 1C, significant EWS were found prior to the manic transition (Kendall’s Tau = .54, corrected p < .001) as well as the depressive transition (Kendall’s Tau = .68, corrected p < 0.001). Figure 1D shows an EWS in the standard deviation prior to the depressive transition (Kendall’s Tau = .75, corrected p < 0.001), but not prior to the manic transition (Kendall’s Tau = .50, corrected p = 0.07)