Major depressive disorder (MDD) is amongst the most prevalent of psychiatric disorders. Unfortunately, a third of patients will not respond to conventional treatments and suffer from treatment-resistant depression (TRD). Repetitive transcranial magnetic stimulation (rTMS) has been proven effective in treating TRD. The research suggests that rTMS acts via neuroplastic effects on the brain, which can be measured by changes in hippocampal and amygdala volume as well as cortical thickness. This sham-controlled study investigates longitudinal effects of rTMS on the volumes of the hippocampus and amygdala and cortical thickness in patients with chronic TRD. 31 patients received 20 sessions of high-frequency rTMS (N = 15) or sham treatment (N = 16) over the left dorsolateral prefrontal cortex during 4 consecutive weeks. Using structural magnetic resonance imaging, we investigated longitudinal treatment effects on hippocampus and amygdala volume as well as thickness of the paralimbic cortex. We found no clinical differences between the active and sham rTMS group. Longitudinal changes in hippocampal and amygdala volume did not differ significantly, although males showed a significant decrease in left amygdala volume, irrespective of treatment group. Changes in cortical thickness of the paralimbic cortex differed significantly between the active and sham groups. Most notably, the increase in cortical thickness of the isthmus of the left cingulate gyrus was greater in the active as compared to the sham rTMS group. Our data suggest that rTMS can induce neuroplastic changes, particularly in cortical thickness, independent of treatment response. We also found longitudinal changes in amygdala volume in males. For clinical effects to follow these neuroplastic effects, more intensive rTMS treatment might be needed in chronically depressed patients.Trial registration number: ISRCTN 15535800, registered on 29-06-2017.

中文翻译：

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rTMS 对慢性难治性抑郁症神经可塑性的纵向影响。

重度抑郁症（MDD）是最普遍的精神疾病之一。不幸的是，三分之一的患者对常规治疗没有反应，并患有难治性抑郁症 (TRD)。重复经颅磁刺激 (rTMS) 已被证明可有效治疗 TRD。研究表明，rTMS 通过对大脑的神经可塑性效应起作用，这可以通过海马和杏仁核体积以及皮质厚度的变化来测量。这项假对照研究调查了 rTMS 对慢性 TRD 患者海马和杏仁核体积以及皮质厚度的纵向影响。31 名患者在连续 4 周内接受了 20 次高频 rTMS（N = 15）或假治疗（N = 16）在左背外侧前额叶皮层。使用结构磁共振成像，我们研究了纵向治疗对海马和杏仁核体积以及旁边缘皮层厚度的影响。我们发现活动和假 rTMS 组之间没有临床差异。海马和杏仁核体积的纵向变化没有显着差异，尽管男性的左侧杏仁核体积显着减少，与治疗组无关。活动组和假手术组的副边缘皮质厚度变化显着不同。最值得注意的是，与假 rTMS 组相比，活动组左扣带回峡部皮质厚度的增加更大。我们的数据表明，rTMS 可以诱导神经可塑性变化，特别是皮质厚度，与治疗反应无​​关。我们还发现男性杏仁核体积的纵向变化。对于跟随这些神经可塑性效应的临床效果，慢性抑郁症患者可能需要更密集的 rTMS 治疗。试验注册号：ISRCTN 15535800，注册于 2017 年 6 月 29 日。