In this study of cognitive-behavioral therapy for depression, many patients
experienced large symptom improvements in a single between sessions. These
sudden gains' average magnitude was 11 Beck Depression Inventory points, a
ccounting for 50% of these patients' total improvement. Patients who experi
enced sudden gains were: less depressed than the other patients at posttrea
tment, and they remained so IB months later. Substantial cognitive changes
were observed in the therapy sessions preceding sudden gains, but few cogni
tive! changes were observed in control sessions, suggesting that cognitive
change in the pregain sessions triggered the sudden gains, improved therape
utic alliances were also observed in the therapy sessions immediately after
the sudden gains, as were additional cognitive changes, suggesting a three
-stage model for these patients' recovery: preparation --> critical session
/sudden gain --> upward spiral.