OBJECTIVES: Repetitive transcranial magnetic stimulation (rTMS) has been shown
to improve depressive symptoms. We designed and carried out the following left
prefrontal rTMS study to determine the safety, feasibility, and potential
efficacy of using TMS to treat the depressive symptoms of bipolar affective
disorder (BPAD). METHODS: We recruited and enrolled 23 depressed BPAD patients
(12 BPI depressed state, nine BPII depressed state, two BPI mixed state).
Patients were randomly assigned to receive either daily left prefrontal rTMS (5
Hz, 110% motor threshold, 8 sec on, 22 sec off, over 20 min) or placebo each
weekday morning for 2 weeks. Motor threshold and subjective rating scales were
obtained daily, and blinded Hamilton Rating Scale for Depression (HRSD) and
Young Mania Rating Scales (YMRS) were obtained weekly. RESULTS: Stimulation was
well tolerated with no significant adverse events and with no induction of
mania. We failed to find a statistically significant difference between the two
groups in the number of antidepressant responders (>50% decline in HRSD or HRSD
<10 - 4 active and 4 sham) or the mean HRSD change from baseline over the 2
weeks (t = -0.22, p = 0.83). Active rTMS, compared with sham rTMS, produced a
trend but not statistically significant greater improvement in daily subjective
mood ratings post-treatment (t = 1.58, p = 0.13). The motor threshold did not
significantly change after 2 weeks of active treatment (t = 1.11, p = 0.28).
CONCLUSIONS: Daily left prefrontal rTMS appears safe in depressed BPAD subjects,
and the risk of inducing mania in BPAD subjects on medications is small. We
failed to find statistically significant TMS clinical antidepressant effects
greater than sham. Further studies are needed to fully investigate the potential
role, if any, of TMS in BPAD depression.