Predictors of antidepressant response in clinical trials of transcranial magnetic stimulation

Abstract

Although previous clinical trials have suggested that repetitive transcranial magnetic stimulation (rTMS) has a significant antidepressant effect, the results of these trials are heterogeneous. We hypothesized that individual patients' characteristics might contribute to such heterogeneity. Our aim was to identify predictors of antidepressant response to rTMS. We pooled data from six separate clinical trials conducted independently, which evaluated the effects of rapid rTMS of the left dorsolateral prefrontal cortex in patients with major depression. We investigated 195 patients with regard to demographic, depression and treatment characteristics, psychiatric and drug history. Results showed that age and treatment refractoriness were significant negative predictors of depression improvement when adjusting these variables to other significant predictors and confounders. These findings were not confounded by methodological differences from the six studies, as the results were adjusted for the study site. In conclusion TMS antidepressant therapy in younger and less treatment-resistant patients is associated with better outcome.

Functional connectivity between the amygdala and prefrontal cortex in medication-naive individuals with major depressive disorder

“…The decreased amygdyala-left rPFC functional connectivity in response to fearful emotion may be related to the hemispheric asymmetry, which has been demonstrated in individuals with MDD. [41][42][43][44] The balance between the right and left hemispheres is very important to adaptive emotion regulation, and hemispheric asymmetry has been observed in normal affective processing of positive and negative emotions. 45,46 Previous studies have indicated that the left PFC activates more during the regulation of negative affect 47 and approach-related positive affect.…”

Impaired interhemispheric connectivity in medicationnaive patients with major depressive disorder

“…43 Abnormalities in interhemispheric functioning have been reported previously in patients with MDD. [2][3][4][5][6][7][44][45][46] Lesions in the anterior CC have been implicated in emotional dysregu lation 47 and the hemispheric lateralization of prefrontal abnormalities associated with acute depressive episodes. 48 Mechan isms that may underlie the development of abnormalities in anterior genu CC white matter organization are suggested by recent postmortem studies.…”

“…Studies of mood and emotion processing in healthy and neuropsychiatric populations suggest processing of negative emotions relies mainly on the right cerebral hemisphere, whereas the left hemisphere is dominant for positive emotion processing. 1 Convergent evidence from investigations involving repetitive transcranial magnetic stimulation (rTMS), [2][3][4] electroenceph alography (EEG) 5,6 and functional magnetic resonance im aging (fMRI) 7 suggest that an imbalance between left and right hemispheric activity may contribute to the patho physio logy of major depressive disorder (MDD). Abnormal ities particularly in the functional balance between the left and right prefrontal cortices are implicated in the disorder.…”

Parkinson's disease treatments: focus on transcranial direct current stimulation (tDCS)

“…In support of this hypothesis, lesser effects of non-invasive brain stimulation have been observed in the elderly compared to a younger population. 74 Nevertheless, other studies 25 have shown that 1mA stimulation for 20 minutes is able to induce behavioral …”