Aims: Low-frequency right prefrontal repetitive transcranial magnetic stimulation (rTMS) is effective in treating depression, and its antidepressant effects have proven to correlate with decreases in cerebral blood flow (CBF) in the orbitofrontal cortex and subgenual cingulate cortex. However, a predictor of treatment response to low-frequency right prefrontal rTMS in depression has not been identified yet. The aim of this study was to estimate regional CBF in the frontal regions and investigate the correlation with treatment response to low-frequency right prefrontal rTMS in depression.
Methods: We examined 26 depressed patients for the correlation between treatment response to rTMS and regional CBF in the frontal regions, by analyzing their brain scans with 99mTc-ethyl cysteinate dimer before rTMS treatment. CBF in 16 brain regions was estimated using fully automated region of interest analysis software. Two principal components were extracted from CBF in 16 brain regions by factor analysis with maximum likelihood method and Promax rotation with Kaiser normalization.
Results: Sixteen brain regions were divided into two groups: dorsolateral prefrontal cortex (superior frontal, medial frontal, middle frontal, and inferior frontal regions) and ventromedial prefrontal cortex (anterior cingulate, subcallosal, orbital, and rectal regions). Treatment response to rTMS was not correlated with CBF in the dorsolateral prefrontal cortex, but it was correlated with CBF in the ventromedial prefrontal cortex.
Conclusion: These findings suggest that CBF in the ventromedial prefrontal cortex may be a potential predictor of low-frequency right prefrontal rTMS, and depressed patients with increased CBF in the ventromedial prefrontal cortex may show a better response.