Lack of adverse cognitive effects of 1 Hz and 20 Hz repetitive transcranial magnetic stimulation at 100% of motor threshold over left prefrontal cortex in depression

Objective: The potential therapeutic effects of repetative transcranial magnetic stimulation (rTMS) are being examined in various neuropsychiatric illnesses. This study assesses the Cognitive performance of depressed patients receiving high or ow frequency rTMS for 10 days. Methods: 18 depressed patients participated in a randomized double-blind cross-over study exploring the antidepressant effects of 2 weeks (10 daily) of sham, 1 Hz, or 20 Hz rTMS administered over the left dorsolateral prefrontal cortex at 100% of motor threshold (MT). A subgroup completed a battery of cognitive tests at baseline and following each 2-week phase of treatment, and differences in performance were assessed using paired t-tests and were correlated with the degree of clinical improvement using Hamilton Depression Rating Scale scores. Results: There were no major changes in cognitive test scores as a result of 10 days of either 1 Hz or 20 Hz rTMS. Moreover, any minor attenuations in cognition were not related to the degree of clinical improvement. Conclusions: Cognitive functioning in many domains following 2 weeks of 1 Hz or 20 Hz rTMS at 100% MT over the left dorsolateral prefrontal cortex in depressed patients is not disrupted.