Association between antidepressant resistance in unipolar depression and subsequent bipolar disorder: cohort study.
BACKGROUND
People with major depressive disorder who fail to respond to adequate trials of antidepressant treatment may harbour hidden bipolar disorder.


OBJECTIVE
We aimed to compare the rates of a change in diagnosis to bipolar disorder among people with major depressive disorder with stratified responses to antidepressants during an 8-year follow-up period.


METHODS
Information on individuals with major depressive disorder identified during 2000 (cohort 2000, n = 1485) and 2003 (cohort 2003, n = 2459) were collected from a nationally representative cohort of 1,000,000 health service users in Taiwan. Participants responding well to antidepressants were compared with those showing poor responses to adequate trials of antidepressants.


RESULTS
In 7.6-12.1% of those with a diagnosis of unipolar major depressive disorder this diagnosis was subsequently changed to bipolar disorder, with a mean time to change of 1.89-2.98 years. Difficult-to-treat participants presented higher rates of change to a bipolar diagnosis (25.6% in cohort 2000; 26.6% in cohort 2003) than easy-to-treat participants (8.8-8.9% in cohort 2000; 6.8-8.6% in cohort 2003; P<0.0001). Regression analysis showed that the variable most strongly associated with the change in diagnosis was antidepressant use history. The difficult-to-treat participants were associated most with diagnostic changing (cohort 2000: odds ratio (OR) = 1.88 (95% CI 1.12-3.16); cohort 2003: OR = 4.94 (95% CI 2.81-8.68)).


CONCLUSIONS
This is the first large-scale study to report an association between antidepressant response history and subsequent change in diagnosis from major depressive disorder to bipolar disorder. Our findings support the view that a history of poor response to antidepressants in unipolar depression could be a useful predictor for bipolar diathesis.
Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan.
Cheng-Ta
CT
Li
Ya-Mei
YM
Bai
Yu-Lin
YL
Huang
Ying-Sheue
YS
Chen
Tzeng-Ji
TJ
Chen
Ju-Yin
JY
Cheng
Tung-Ping
TP
Su
D000328:Adult; D000928:Antidepressive Agents / Q000627:therapeutic use*; D001008:Anxiety Disorders / Q000453:epidemiology; D001714:Bipolar Disorder / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology*; D003865:Major Depressive Disorder / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology; D061218:Depressive Disorder, Treatment-Resistant / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology*; D003937:Diagnosis, Differential; D004198:Disease Susceptibility; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D038801:International Classification of Diseases; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data*; D019966:Substance-Related Disorders / Q000453:epidemiology; D013624:Taiwan / Q000453:epidemiology
D000928:Antidepressive Agents