Repetitive transcranial magnetic stimulation in trauma-related conditions

Abstract

Some of trauma-exposed individuals develop posttraumatic stress disorder (PTSD), an incapacitating psychiatric disorder that is characterized by intrusion, avoidance, negative changes in mood and cognition, and hyperarousal. A number of other trauma-related conditions are very frequently found in individuals with PTSD. Traumatic brain injury (TBI) is one of the most frequently observed trauma-related conditions that trauma-exposed individuals with PTSD may experience. TBI refers to transient or permanent brain dysfunction that results in a wide range of neurological, cognitive, and psychiatric symptoms. These trauma-related conditions significantly affect one's quality of life, leading to substantial disability and socioeconomic burden. As the prevalence of PTSD with comorbid TBI is increasing in the general population along with the rates of crimes and accidents, effective prevention and intervention strategies are necessitated. However, a definitive treatment for PTSD with comorbid TBI is still lacking, resulting in high rates of treatment resistance and chronicity. It is essential to investigate the neurobiological mechanisms and potential therapeutics of PTSD with comorbid TBI. Yet, a few repetitive transcranial magnetic stimulation (rTMS) studies have recently investigated therapeutic efficacy in treatment-resistant patients with PTSD and/or TBI. Thus, this article reviews rTMS studies in trauma-related conditions, mainly focusing on PTSD and PTSD with TBI as one of the comorbidities. The review focuses on the applications of rTMS in reducing PTSD symptoms with and without comorbidities based on differential parameters and effects of rTMS as well as concomitant clinical conditions. The section on PTSD with comorbidities focuses on TBI with neurological, cognitive, and psychiatric symptoms. Although there were some inconsistencies in the clinical outcomes and optimized parameters of rTMS applied in PTSD and TBI, low frequency stimulation over the hyperactive frontal regions and/or high frequency stimulation over the hypoactive frontal regions generally improved the clinical symptoms of PTSD and TBI. Lastly, the limitations of the rTMS studies in PTSD and TBI as well as potential directions for future research are discussed.

Keywords: brain; neuromodulation; posttraumatic stress disorder; repetitive transcranial magnetic stimulation; trauma; traumatic brain injury.

Figure 1

Schematic representation of the target brain regions according to frequency of rTMS among trauma-exposed individuals in the review: (A) PTSD patients and (B) TBI patients. Notes: The size of the nodes is proportional to the number of rTMS studies allocated to each target brain region. The color of the nodes reflects the frequency of rTMS applied to each target region: high frequency stimulation (>1 Hz) (red color) and low frequency stimulation (≤1 Hz) (blue color). Abbreviations: DLPFC, dorsolateral prefrontal cortex; HF, high frequency; L, left; LF, low frequency; PMC, primary motor cortex; PTSD, posttraumatic stress disorder; R, right; rTMS, repetitive transcranial magnetic stimulation; TBI, traumatic brain injury.