Bipolar Disorder XI: Continuous Decline of Lithium Response Inversely Correlated to Time Before Drug Administration in Relation to Onset of a Bipolar Disorder.

Background: Bipolar disorder (BD) is a severe disease affecting 1% of the general population. BD comprises recurrent depressive, hypomanic, and manic episodes. BD occurs as type I (BDI) and type II (BDII). In this study, we investigated the duration of illness before lithium treatment started in BDI and BDII. Methods: A long-term follow-up study of 192 patients with BD (diagnosed following DSM-IV criteria) were collected from lithium dispensaries. Patients with BDI and BDII were divided according to lithium response. Results: We found that patients with BD responded better to lithium if the treatment was introduced early after diagnosis compared with when treatment was started later in the course of the disease. From the diagnosis of BD, BDI was in general introduced earlier to lithium treatment compared with BDII. Logistic regression analysis showed that a continuous decline in lithium response was associated with the time lag before drug administration in relation to onset of the BD. To the best of our knowledge, we can for the first time report that lithium response is associated with a continuous decrease over time from the onset of BD until the drug treatment is started. Conclusions: A short duration of illness before introduction of lithium treatment is a predictor of better lithium response regardless of whether BDI or BDII is present. Lithium response seems to gradually decline with an increasing duration of illness before lithium treatment is started.