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Frontal asymmetry plays a major role in depression. However, patients with treatment-resistant depression (TRD) have widespread hypofrontality. We investigated whether patients with TRD have a characteristic frontal activation pattern in functional near-infrared spectroscopy (fNIRS) findings and how the frontal cortex responds to different levels of cognitive tasks.We enrolled 27 right-handed patients with TRD, 27 patients without TRD and 27 healthy controls. We used multichannel fNIRS to evaluate activation of the bilateral dorsolateral prefrontal cortex (DLPFC), ventrolateral prefrontal cortex (VLPFC) and left motor area in response to 3 tasks: finger tapping, a low cognitive-load motor task; verbal fluency, a moderate cognitive-load task; and a dual task involving simultaneous finger tapping and verbal fluency, a high cognitive-load task.We found significant between-group differences in left DLPFC activation for all 3 tasks. The healthy controls had cortical activation in the left motor area during finger tapping and the bilateral frontal cortex during the dual task. However, patients without TRD had right VLPFC activation during finger tapping and left DLPFC activation during the dual task. Patients with TRD had bilateral DLPFC activation during finger tapping but exhibited increased bilateral VLPFC and left motor area activation during verbal fluency and increased left motor area activation during the dual task. In healthy controls and patients without TRD, we found that the right VLPFC was positively correlated with depression severity.Our cohort included only patients with late-onset depression.We found different patterns of abnormal frontal activation between patients with and without TRD. In patients without TRD, the right prefrontal cortex (PFC) was recruited during simple motor tasks. However, in patients with TRD, the bilateral PFC was recruited during simple tasks and motor cortical resources were used compensatorily during PFC-demanding complex cognitive tasks.

Prolonged intermittent theta burst stimulation (piTBS) with triple doses of the standard protocol is an updated form of repetitive transcranial magnetic stimulation, and it is an effective add-on intervention for major depressive disorder. In the present study, our objective was to investigate the antidepressant efficacy of piTBS monotherapy. Efficacy between the standard 5-cm method and magnetic resonance imaging (MRI)-guided coil positioning to the left dorsolateral prefrontal cortex method was also compared.In the present double-blind, randomized, sham-controlled trial, 105 patients with recurrent depression who exhibited no responses to at least one adequate antidepressant treatment for the prevailing episode were assigned randomly to one of three groups: piTBS monotherapy (n = 35), repetitive transcranial magnetic stimulation monotherapy (n = 35), or sham stimulation (n = 35). The acute treatment period was 2 weeks. Half of the patients were randomized to MRI navigation in each group.No serious adverse events were observed. The piTBS group exhibited significantly greater decreases in depression scores than the sham group at week 2 (-40.0% vs. -13.9%; p.001 after correcting for multiple comparisons by Bonferroni [effect size (Cohen's d) = 1.12]), and the odds ratio for responses was high. The MRI navigation method (-32.4%) did not yield better antidepressant effects than the standard method (-40.6%). Brain stimulation and 17-item Hamilton Depression Rating Scale changes in the first week were the most important variables for predicting antidepressant responses.Left prefrontal piTBS monotherapy is effective for the treatment of recurrent depression, and the MRI-guided method of coil targeting is not better than the standard method.

Background Repetitive transcranial magnetic stimulation (rTMS) is the current treatment option for major depression (MD). Theta-burst stimulation (TBS), a variation of rTMS, affords a short stimulation duration, low stimulation pulse intensity, and possibility to improve rTMS efficiency. This systematic review and meta-analysis examined the studies on efficacy and tolerability of TBS in patients with MD. Methods This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched the literature from 1990 until May 24, 2020, and performed a random-effects meta-analysis by including response and remission rates of depression and dropout rates as main outcome measures. Results In total, 10 studies including 6 randomized controlled trials (RCTs; n = 294) and 4 uncontrolled clinical trials (non-RCTs; n = 297) were included. The overall effect size of response rate and remission rates were 0.38 (95% confidence interval [CI]: 0.29–0.48) and 0.20 (95% CI: 0.13–0.29), respectively. Notably, the TBS group showed favorable efficacy without major adverse events. Conclusions TBS treatment was more efficient in terms of time and energy than the standard rTMS was. Our meta-analysis provided evidence that the application of TBS to the dorsolateral prefrontal cortex is associated with significant antidepressant effects along with favorable tolerability.

BACKGROUND The relationship between severe inflammation and clinical depression in the context of major medical illnesses has been addressed, but the relationship between inflammation caused by mild infections and clinical depression is unclear. We aimed to examine whether a history of repeated low-grade infections (RLGI) in medically healthy subjects (MHS) could increase their vulnerability to major depressive disorder (MDD) (ICD-9-CM) and whether RLGI could be associated with higher resistance to antidepressants in those developing MDD. METHOD A nationwide, population-based cohort study (January 1996 to December 2011) was conducted for MHS with and without a history of RLGI. The rates of MDD during an up to 8-year follow-up period were compared between the 2 groups in 2 independent cohorts. The stratified responses to adequate antidepressant trials, including easy-to-treat (ETT) and difficult-to-treat (DTT) responses, were also compared in the MDD patients. RESULTS During the follow-up, the 2 cohorts consistently revealed that the RLGI(+) (ie, high-inflammation; n = 727) group had a significantly higher chance of developing MDD over time than the RLGI(-) (ie, low-inflammation; n = 443) group: Cox proportional hazards regression models showed that the hazard ratio associated with a history of RLGI was 1.369 to 1.911 (P < .001), after adjusting for confounding factors. The RLGI(+) group was consistently associated with a higher likelihood of DTT responses than was the RLGI(-) group (Cohort-2002: 11.5% vs 7.6%; Cohort-2004: 11.8% vs 4.3%; P < .05 by Wald χ² tests in both cohorts). CONCLUSIONS This is the first large-scale retrospective cohort study to report a reliable temporal association between a history of RLGI and subsequent diagnosis of MDD and poor responses to antidepressants in 2 independent cohorts. Our data support the view that repeated mild infections play a role in the pathophysiology of MDD and antidepressant-resistant depression.