Mechanisms of Transcranial Magnetic Stimulation Treating on Post-stroke Depression

Why would you want to use this for depression when you get two-for-one on SSRIs? Don't listen to me, I'm not medically trained.

Common antidepressant can help stroke patients improve movement and coordination Sept. 2015 

Antidepressants may help people recover from stroke even if they are not depressed Jan. 2013

Mechanisms of Transcranial Magnetic Stimulation Treating on Post-stroke Depression

Xiaoqin Duan, Gang Yao, Zhongliang Liu, Ranji Cui and Wei Yang^*

• Jilin Provincial Key Laboratory on Molecular and Chemical Genetics, The Second Hospital of Jilin University, Changchun, China

Post-stroke depression (PSD) is a neuropsychiatric affective disorder that can develop after stroke. Patients with PSD show poorer functional and recovery outcomes than patients with stroke who do not suffer from depression. The risk of suicide is also higher in patients with PSD. PSD appears to be associated with complex pathophysiological mechanisms involving both psychological and psychiatric problems that are associated with functional deficits and neurochemical changes secondary to brain damage. Transcranial magnetic stimulation (TMS) is a non-invasive way to investigate cortical excitability via magnetic stimulation of the brain. TMS is currently a valuable tool that can help us understand the pathophysiology of PSD. Although repetitive TMS (rTMS) is an effective treatment for patients with PSD, its mechanism of action remains unknown. Here, we review the known mechanisms underlying rTMS as a tool for better understanding PSD pathophysiology. It should be helpful when considering using rTMS as a therapeutic strategy for PSD.

Introduction

Stroke is the most common cause of adult disability in developing countries (Kaadan and Larson, 2017) and has both physical and economic repercussions for patients. Post-stroke depression (PSD) is a severe and fearful complication that occurs in nearly one third of patients who suffer stroke and can even occur in patients who have suffered only a minor stroke or transient ischemic attack (TIA; Carnes-Vendrell et al., 2016). PSD can affect functional ability, rehabilitation outcome, and quality of life, and is related to a higher mortality rate of stroke patients (Miranda et al., 2018). Additionally, stroke severity is an important risk factor for PSD, as is the mental history of the patient. Preventing PSD requires participation from family members and society (Shi et al., 2017). It appears to be associated with complex pathophysiological mechanisms involving both psychological and psychiatric problems that are associated with functional deficits and neurochemical changes secondary to brain damage. Although antidepressants are considered the treatment of choice for PSD, the benefits are not perfect. Indeed, whether pharmacological treatment is needed to prevent PSD or improve neurological outcomes after stroke is uncertain (Kim, 2016; Xu et al., 2016). Fortunately, studies suggest that transcranial magnetic stimulation (TMS) is beneficial for patients with PSD (Gu and Chang, 2017; Shen et al., 2017).

TMS is an important technique for noninvasive brain stimulation (NIBS; Edwards et al., 2017). NIBS, using electromagnetic waves and direct electrical current, is a new frontier in treating neuropsychiatric illnesses or psychiatric maladies (Gupta and Adnan, 2018). Several types of NIBS have been developed over the years, including electroconvulsive therapy (ECT), transcranial alternating current stimulation (tACS), magnetic seizure therapy (MST), TMS and transcranial direct current stimulation (tDCS). Among them, ECT is the best at reducing depression and has unparalleled efficacy even in older populations. However, the risk of amnesia is a severely limiting factor. While tACS has several advantages including biphasic and sinusoidal currents, the ability to entrain large neuronal populations, and subtle control over somatic effects, its best practices remain unclear and further study is required (Tavakoli and Yun, 2017). MST is a proposed form of electrotherapy using magnetic brain stimulation. It preserves the efficacy of ECT while reducing the risk of amnesia through the more precise localization offered by magnetic stimulation (Luber et al., 2013). However, its clinical effects still need to be studied. The most commonly used NIBS are TMS and tDCS. tDCS modulates membrane potential via electrical currents (Rektorová and Anderková, 2017). It does not directly induce action potentials in neurons, but instead is believed to influence spontaneous activity of targeted brain networks. TMS can be directed more specifically than tDCS. Additionally, it can exert a causal influence on brain networks and its clinical efficacy has already been established in the treatment of mental disorders (Hendrikse et al., 2017). Among all the types of NIBS, TMS—especially repetitive TMS (rTMS)—is the best at controlling the frequency and the location of stimulation. This advantage, in addition to others, has opened up new possibilities for clinical exploration and treatment of neuropsychiatric conditions. Meta-analysis of the literature shows that rTMS can combat PSD and that it is actively used in therapy (Klein et al., 2015). However, its exact mechanism of action is still unknown. Here, we explore what we know about the mechanisms underlying rTMS treatment of PSD.

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