Background. Though previous studies have clearly
shown that lithium affords prophylaxis in bipolar affective disorder,
these studies have not demonstrated the persistence of this
prophylactic effect beyond the first year of recovery.
Methods. One hundred and eighty-one patients with bipolar
affective disorder recovered during 5 years of semi-annual follow-up.
After 8 weeks of recovery, 139 were taking lithium prophylaxis and 42
were not. Analyses used drug status (lithium v. no-lithium)
as a censoring variable to compare these two groups by
interval-specific probabilities of recurrence.
Results. Recurrence was initially less likely in the
lithium group but interval-specific probabilities of recurrence did
not consistently favour either group after the first 32 weeks of
Conclusions. Biases in treatment decisions may have both
reduced the size and altered the specificity of the lithium effects
seen here. Nevertheless, the apparent transience of lithium
prophylactic effects is unexplained and may reflect important,
physiological differences between relapse and recurrence. This
possibility invites a controlled lithium discontinuation study, with
gradual taper, of patients who have had at least 8 months of sustained