Objective: The authors sought to determine whether the manic/mixed episode
distinction in patients with bipolar disorder runs true over time.
Method: Over an 11-year period, the observed distribution of manic and mixe
d episodes (N=1,224) for patients with three or more entries in the managem
ent information system of a community mental health center (N=241) was comp
ared to the expected distribution determined by averaging 1,000 randomly ge
nerated simulations.
Results: Episodes were consistent (all manic or all mixed) in significantly
more patients than would be expected by chance.
Conclusions: These data suggest a pattern of diagnostic stability over time
for manic and mixed episodes in patients with bipolar disorder. Careful pr
ospective studies of this issue are needed.