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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recently, repetitive TMS (rTMS) has been used as a potential treatment for depression. Several studies have shown antidepressant effects of rapid rTMS over the left dorsolateral prefrontal cortex (DLPFC), whereas some studies suggested the effectiveness of slow rTMS over the right DLPFC. Despite the growing interest in therapeutic application of rTMS, the precise mechanisms for rTMS over the DLPFC are still unknown. To clarify these mechanisms for slow rTMS over the right prefrontal cortex, we measured regional cerebral blood flow (rCBF) during real or sham rTMS and after stimulation using repeated l5O-labeled H2O PET scanning in seven healthy subjects. We found that slow rTMS over the right DLPFC could produce significant rCBF increase in the ipsilateral anterior cingulate cortex (ACC) during stimulation as compared with sham stimulation. The lasting activation occurred in the ipsilateral medial prefrontal cortex, contralateral ventrolateral PFC, and the contralateral ventral striatum. These data indicate that slow rTMS is able to produce rCBF changes in the paralimbic system and frontal cortex. We conclude that the lasting effect on the ventral striatum should reflect modulatory effects of rTMS over the DLPFC on the meso-limbic dopaminergic system that must play critical roles in antidepressant effects.
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PMID:rCBF changes elicited by rTMS over DLPFC in humans. 1610 74

Repetitive transcranial magnetic stimulation (rTMS) holds promise as a therapeutic tool in major depression. However, a means to assess the effects of a single rTMS session on mood to guide subsequent sessions would be desirable. The present study examined the effects of a single rTMS session on an affective go/no-go task known to measure emotional-cognitive deficits associated with major depression. Ten patients with an acute episode of unipolar major depression and eight partially or completely remitted (improved) patients underwent 1 Hz rTMS over the left and right dorsolateral prefrontal cortex prior to task performance. TMS over the mesial occipital cortex was used as a control. We observed significantly improved performance in depressed patients following right prefrontal rTMS. This beneficial effect declined with decreasing depression severity and tended to reverse in the improved group. Left prefrontal rTMS had no significant effect in the depressed group, but it resulted in impaired task performance in the improved group. Our findings indicate that the acute response of depressed patients to rTMS varies with the stimulation site and depression severity. Further studies are needed to determine whether the present paradigm could be used to predict antidepressant treatment success or to individualize stimulation parameters according to specific pathology.
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PMID:Effect of low-frequency transcranial magnetic stimulation on an affective go/no-go task in patients with major depression: role of stimulation site and depression severity. 1635 48

Repetitive transcranial magnetic stimulation (rTMS) is an experimental technology that involves a powerful magnetic pulse applied to the scalp, which is sufficient to cause neuronal depolarization. Transcranial magnetic stimulation has been used in treatment studies for psychiatric disorders, primarily unipolar depression, and as a tool to map brain function. Although thousands of rTMS sessions have been given with few side effects, rTMS can produce serious adverse effects such as an unintended seizure. Safety guidelines for frequency, duration, and intensity of rTMS have aided in the prevention of such adverse side effects. However, the total dose (number of stimuli) able to be delivered safely to human subjects within a day or within a week has not been established. For example, previous rTMS studies as a treatment for depression consisted of delivering 800 to 3,000 magnetic pulses per day, with 8000 to 30,000 magnetic pulses over 2 to 3 weeks. This study examined whether high doses of rTMS within a day or over a week would produce significant side effects. As part of a study to examine rTMS effects in sleep deprivation, we exposed healthy men to 12,960 magnetic pulses a day for up to 3 days in 1 week. This equals 38,880 magnetic pulses over 1 week, which is likely one of the largest exposures of TMS to date. Despite this intense treatment regimen, we failed to produce significant side effects. Doses of up to 12,960 pulses per day appear safe and tolerable in healthy young men.
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PMID:Tolerability and safety of high daily doses of repetitive transcranial magnetic stimulation in healthy young men. 1663 8

Although previous clinical trials have suggested that repetitive transcranial magnetic stimulation (rTMS) has a significant antidepressant effect, the results of these trials are heterogeneous. We hypothesized that individual patients' characteristics might contribute to such heterogeneity. Our aim was to identify predictors of antidepressant response to rTMS. We pooled data from six separate clinical trials conducted independently, which evaluated the effects of rapid rTMS of the left dorsolateral prefrontal cortex in patients with major depression. We investigated 195 patients with regard to demographic, depression and treatment characteristics, psychiatric and drug history. Results showed that age and treatment refractoriness were significant negative predictors of depression improvement when adjusting these variables to other significant predictors and confounders. These findings were not confounded by methodological differences from the six studies, as the results were adjusted for the study site. In conclusion TMS antidepressant therapy in younger and less treatment-resistant patients is associated with better outcome.
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PMID:Predictors of antidepressant response in clinical trials of transcranial magnetic stimulation. 1713 79

This paper reviews the status of some physical therapies for depression. Light is the treatment of choice for seasonal affective disorder. Light is also effective in non-seasonal depression as mono-therapy and as add-on to drug therapy. Exercise is effective in moderate depression, but onset of action, duration and compliance need to be examined. TMS treatment has a moderate, albeit transient effect on depression, but further development is needed before it can be used as a standard treatment. Sleep deprivation has the fastest known antidepressant effect, but the risk of relapse limits its use. New regimens including drugs and light may sustain the response.
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PMID:[Physical therapies for depression--light, exercise, TMS and sleep deprivation]. 1748 44

The study aimed to explore the biological effects of low-frequency repetitive transcranial magnetic stimulation (LFR-TMS) treatment applied to the right prefrontal cortex, comparing this with the effects of high-frequency left-sided (HFL-TMS) in patients with treatment-resistant depression. Twenty-six patients with treatment-resistant depression were randomized to receive either daily LFR-TMS or HFL-TMS treatment for 3 weeks and underwent functional magnetic resonance imaging during a planning task before and after treatment. Patients responded clinically to both forms of treatment with no difference in the degree of response (F1,24 = 0.65;P > 0.05). Low-frequency repetitive transcranial magnetic stimulation resulted in no overall change in task-related activation. However, responders to LFR-TMS demonstrated a bilateral decrease in activity in middle frontal gyrus. In contrast, HFL-TMS produced an increase in activation in left precuneus with responders showing increased activation in several additional regions. Response to LFR-TMS is associated with a bilateral reduction in frontal activation that does not seem to be a nonspecific effect of treatment and differs from the response to HFL-TMS.
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PMID:A functional magnetic resonance imaging study of the effects of low frequency right prefrontal transcranial magnetic stimulation in depression. 1787 82

Short interval intracortical inhibition (SICI) and intracortical facilitation (ICF) were evaluated in the masseter muscles of 12 subjects and the cortical silent period (SP) in nine subjects. Motor evoked potentials (MEPs) were recorded from contralateral (cMM) and ipsilateral (iMM) masseters, activated at 10% of maximal voluntary contraction (MVC). Interstimulus intervals (ISIs) were 2 and 3 ms for SICI, 10 and 15 ms for ICF. TMS of the left masseteric cortex induced MEPs that were larger in the cMM than the iMM; stimulation of right masseteric cortex produced a similar asymmetry in response amplitude. SICI was only observed using a CS intensity of 70% AMT and was equal in both cMM and iMM. SICI was stronger at higher TS intensities, was abolished by muscle activation greater than 10% MVC, and was unaffected by coil orientation changes. Control experiments confirmed that SICI was not contaminated by any inhibitory peripheral reflexes. However, ICF could not be obtained because it was masked by bilateral reflex depression of masseter EMG caused by auditory input from the coil discharge. The SP was bilateral and symmetric; its duration ranged from 35 to 70 ms depending on TS intensity and coil orientation. We conclude that SICI is present in the cortical representation of masseter muscles. The similarity of SICI in cMM and iMM suggests either that a single pool of inhibitory interneurons controls ipsi- and contralateral corticotrigeminal projections or that inhibition is directed to bilaterally projecting corticotrigeminal fibres. Finally, the corticotrigeminal projection seems to be weakly influenced by inhibitory interneurons mediating the cortical SP.
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PMID:Intracortical modulation of cortical-bulbar responses for the masseter muscle. 1849 27

Repetitive transcranial magnetic stimulation (rTMS) has emerged as a promising tool to induce plastic changes that are thought in some cases to reflect N-methyl-d-aspartate-sensitive changes in synaptic efficacy. As in animal experiments, there is some evidence that the sign of rTMS-induced plasticity depends on the prior history of cortical activity, conforming to the Bienenstock-Cooper-Munro (BCM) theory. However, experiments exploring these plastic changes have only examined priming-induced effects on a limited number of rTMS protocols, often using designs in which the priming alone had a larger effect than the principle conditioning protocol. The aim of this study was to introduce a new rTMS protocol that gives a broad range of after-effects from suppression to facilitation and then test how each of these is affected by a priming protocol that on its own has no effect on motor cortical excitability, as indexed by motor-evoked potential (MEP). Repeated trains of four monophasic TMS pulses (quadripulse stimulation: QPS) separated by interstimulus intervals of 1.5-1250 ms produced a range of after-effects that were compatible with changes in synaptic plasticity. Thus, QPS at short intervals facilitated MEPs for more than 75 min, whereas QPS at long intervals suppressed MEPs for more than 75 min. Paired-pulse TMS experiments exploring intracortical inhibition and facilitation after QPS revealed effects on excitatory but not inhibitory circuits of the primary motor cortex. Finally, the effect of priming protocols on QPS-induced plasticity was consistent with a BCM-like model of priming that shifts the crossover point at which synaptic plasticity reverses from depression to potentiation. The broad range of after-effects produced by the new rTMS protocol opens up new possibilities for detailed examination of theories of metaplasticity in humans.
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PMID:Bidirectional long-term motor cortical plasticity and metaplasticity induced by quadripulse transcranial magnetic stimulation. 1870 91

We review studies that have used EEG as a response biomarker in depression, and then present preliminary EEG change data from an ongoing TMS depression treatment trial. These data in 4 depressed subjects over 3 weeks of treatment suggest but do not prove that there may be asymmetry changes that occur both within a daily TMS session and over the course of several weeks that may be associated with antidepressant response. EEG shows potential as a biomarker of response for depression treatments, particularly the brain stimulation devices, which, unlike medications, can focally interact with neural tissue in specific frequency patterns.
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PMID:Prefrontal EEG asymmetry as a potential biomarker of antidepressant treatment response with transcranial magnetic stimulation (TMS): a case series. 1875 61

Repetitive transcranial magnetic stimulation (rTMS) can be used to study metaplasticity in human motor cortex. The term metaplasticity describes a phenomenon where the prior synaptic history of a pathway can affect the subsequent induction of long-term potentiation or depression. In the current study, we investigated metaplasticity in human motor cortex with the use of inhibitory continuous theta-burst stimulation (cTBS). cTBS involves short bursts of high frequency (50 Hz) rTMS applied every 200 ms for 40 s. In the first series of experiments, cTBS was primed with 10 min of intermittent 2 or 6 Hz rTMS. Subjects (n = 20) received priming stimulation at 70% of active motor threshold or 90% of resting motor threshold. In another series of experiments, cTBS was primed with excitatory intermittent theta-burst stimulation (iTBS). iTBS involves a 2 s train of theta-burst stimulation delivered every 10 s for 190 s. Stimuli were delivered over the first dorsal interosseus motor area.. The effect of cTBS alone and primed cTBS on motor cortical excitability was investigated by recording motor-evoked potentials (MEP) in the first dorsal interosseus following single-pulse TMS. MEP area in the cTBS alone condition was not significantly different from cTBS primed with 2 or 6 Hz rTMS. However, priming cTBS with iTBS suppressed MEP area to a greater extent than in cTBS alone. Our results provide further evidence of metaplasticity in human motor cortex when appropriate priming protocols are employed.
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PMID:Priming theta-burst repetitive transcranial magnetic stimulation with low- and high-frequency stimulation. 1936 4


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