Treatment emergent affective switch: a controlled study.

OBJECTIVE: To study the clinical features of treatment emergent affective switch (TEAS) in comparison with spontaneous mania.
METHODS: Twelve patients with TEAS within a 12-week period (average) of starting standard antidepressant medication were compared with 12 patients with spontaneous mania.
RESULTS: Patients with TEAS were older, had longer duration of illness, more previous episodes, higher prevalence of subclinical hypothyroidism, and reported more previous episodes of mania associated with antidepressant use. TEAS was less severe, with a lower incidence of psychotic symptoms, lower Young Mania Rating Scale index score and rarely required hospitalization. The interval from intervention to response and remission was similar in both groups.
CONCLUSION: TEAS was less severe, but had similar duration when compared with spontaneous mania. These results cannot directly answer the question of whether there is a causal relationship between antidepressant use and TEAS. While it is also possible that patients with longer duration of illness and higher cycle frequencies are more likely to experience episodes, it is difficult to attribute lesser severity of TEAS episodes to these clinical factors. Our observations are consistent with the suggestion that patients with longer duration of illness and previous history of TEAS may be at a greater risk of switching to mania during the use of antidepressants.