Low-Frequency rTMS over Right Dorsolateral Prefrontal Cortex in the Treatment of Resistant Depression: Cognitive Improvement Is Independent from Clinical Response, Resting Motor Threshold Is Related to Clinical Response

Abstract

Background: Clinical studies have shown that repetitive transcranial magnetic stimulation (rTMS) is effective in a certain percentage of treatment-resistant depression (TRD). The left dorsolateral prefrontal cortex (DLPFC) 10 Hz rTMS stimulation received FDA approval in 2008, although different rTMS protocols have also shown their effectiveness in reducing depressive symptoms. We investigated the clinical, cognitive and neurophysiologic effects of a 3 weeks’ protocol of low-frequency rTMS applied over the right DLPFC in resistant depression. Methods: Twenty-eight patients with TRD (age range 28–55) received low-frequency rTMS (1 Hz) over the right DLPFC in a 3-week open trial. Hamilton scales for depression and anxiety, Corsi block-tapping test, phonemic verbal fluency, right and left resting motor thresholds were evaluated in each subject over the trial period. Results: At the end of the trial 42.9% of the subjects were considered as responders. A significant reduction of both HAMD (p < 0.001) and HAMA (p < 0.01) total scores was observed. At the 3rd week, the performances in Corsi test (p < 0.02) and phonemic verbal fluency (p = 0.065) were improved independently from depressive symptoms variation. At the end of the rTMS protocol, a significantly decreased left hemisphere resting motor threshold was registered (p < 0.01), while right hemisphere resting motor threshold did not show significant variation. Conclusion: Low-frequency rTMS over the right DLPFC appeared effective in 42.9% of depressive resistant subjects in this sample. A significant decrease in left hemisphere resting motor threshold was observed only in responders, while a trend for improvement in cognitive function has been found and appeared independent from clinical response.

The Effects of Repetitive Transcranial Magnetic Stimulation on Cognitive Performance in Treatment-Resistant Depression. A Systematic Review

“…Based on the main studies included in the present review, 7 studies [45,46,47,48,49,50,51]reported positive findings supporting the association between rTMS treatment and neurocognition, whereas one study [52] suggested the existence of only a trend towards improvements in the neurocognitive profile using rTMS, and another study [53] found no difference in the neurocognitive profiles of those who were treatment responders and those who were nonresponders to rTMS treatment.…”

“…The first is the study of Pallanti et al [52] who found that low-frequency rTMS appeared effective in 42.9% of depressive resistant subjects, but the performances regarding the Corsi test and phonemic verbal fluency were improved independently from depressive symptoms variation. A significantly reduced left hemisphere resting motor threshold was registered at the end of the rTMS protocol.…”

“…Based on the main findings, most (16) of the selected studies [23,25,28,37,38,39,40,43,45,46,47,48,49,50,51,54] supported the association between rTMS and neurocognitive effects; only two studies [52,53] suggested the existence of a trend towards improvements in neurocognitive profile using rTMS, and some (4) studies [36,41,42,44] did not confirm this association (tables 1, 2, 3). …”

No Change in Neuropsychological Functioning After Receiving Repetitive Transcranial Magnetic Stimulation Treatment for Major Depression

“…Interestingly, one session of 10 Hz TMS to the left dorsolateral prefrontal cortex (LDLPFC) improved selective attention in non-depressed individuals without inducing a change in mood 36 . In a clinical trial, Pallanti and colleagues found that improvements in depression were independent of improvements in the Corsi Block Tapping test and verbal fluency 37 . Similarly, Kedzior and colleagues found that neuropsychological variables did not correlate with depression scores after 20 sessions of TMS 31 .…”

Effects of repetitive transcranial magnetic stimulation on non-veridical decision making

“…High frequency stimulation is often applied in sequences, where rapid bursts of stimulation are repeated at certain intervals. 10 Hz left DLPFC stimulation is a standard protocol for treatment of major depression (Pallanti et al 2012).…”