Sudden gains in day-to-day change: Revealing nonlinear patterns of individual improvement in depression.

At the day-level, patterns of improvement are nonlinear for most patients. Sudden gains occur within various forms of overall change and are associated with treatment response. Clinically relevant improvements in depression occur both gradually and abruptly, and this finding allows for the possibility that the remission process functions according to dynamical systems principles. (PsycINFO Database Record (c) 2020 APA, all rights reserved).