Cognitive effects of 1-and 20-Hertz repetitive transcranial magnetic stimulation in depression: Preliminary report

Objective: To determine the cognitive effects of daily repetitive transcran ial magnetic stimulation (rTMS) administered under the conditions of a trea tment trial for major depression, Background: Although daily left dorsal pr efrontal rTMS has improved mood in some patients with treatment-refractory depression, potential cognitive side effects of extended daily treatment ha ve not been systematically studied. Method: In a randomized double-blind tr eatment study, 10 subjects (mean age, 42 +/- 15 years) with an episode of m ajor depression received either 2 weeks of low-frequency (1 Hz) or high-fre quency (20 Hz) rTMS (800 pulses, 20 trains over 20 minutes, 80% of motor th reshold, 5 days per week) to the left dorsolateral prefrontal cortex and th en were crossed over to the other treatment condition. Patients received co gnitive testing at baseline and after the first and second weeks of low- or high-frequency rTMS, which was examined by repeated-measures ANOVA. Result s: Of 16 cognitive measures tested after 1 or 2 weeks of rTMS compared with baseline status, none showed deterioration, and the only significant main treatment effect indicated improvement on a list-recall test from pre- to p ost-rTMS after 1 week (p <0.05). Conclusions: These preliminary data sugges t no gross deleterious cognitive effects of 2 weeks of 1- or 20-Hz rTMS at 80% of motor threshold over the left prefrontal cortex. Further cognitive s tudies of the effects of rTMS at other parameters used in clinical trials f or mood disorders remain to be undertaken.