Comparison of pre-episode and pre-remission states using mood ratings from patients with bipolar disorder.

Daily self-reported mood ratings from patients with bipolar disorder were analyzed to see if the 60 days before an episode of hypomania or depression (pre-episode state) could be distinguished from the 60 days before a month of euthymia (pre-remission state), and if a pre-hypomanic state could be distinguished from a pre-depressed state. Data were available from 98 outpatients with bipolar disorder, who returned about one year of daily data, and received treatment as usual. The approximate entropy (ApEn), mean mood and mood variability (standard deviation) were determined for 53 pre-hypomanic states, 42 pre-depressive states, and 65 pre-remission states.There was greater serial irregularity (ApEn) and greater variability in mood in the pre-episode than the pre-remission state. There was greater serial irregularity (ApEn) but no difference in variability in mood in the pre-hypomanic state when compared to the pre-depressed state. ApEn can distinguish between the pre-episode, pre-remission, pre-hypomanic and pre-depressive states. Using daily mood ratings, pre-episode changes were detected before the episode onset. Further investigation to relate the pre-episode and pre-remission states to other clinical and biological data is indicated.