Marco Antonio Marcolin

Anodal transcranial direct current stimulation of prefrontal cortex enhances working memory

Previous studies have claimed that weak transcranial direct current stimulation (tDCS) induces persisting excitability changes in the human motor cortex that can be more pronounced than cortical modulation induced by transcranial magnetic stimulation, but there are no studies that have evaluated the effects of tDCS on working memory. Our aim was to determine whether anodal transcranial direct current stimulation, which enhances brain cortical excitability and activity, would modify performance in a sequential-letter working memory task when administered to the dorsolateral prefrontal cortex (DLPFC). Fifteen subjects underwent a three-back working memory task based on letters. This task was performed during sham and anodal stimulation applied over the left DLPFC. Moreover seven of these subjects performed the same task, but with inverse polarity (cathodal stimulation of the left DLPFC) and anodal stimulation of the primary motor cortex (M1). Our results indicate that only anodal stimulation of the left prefrontal cortex, but not cathodal stimulation of left DLPFC or anodal stimulation of M1, increases the accuracy of the task performance when compared to sham stimulation of the same area. This accuracy enhancement during active stimulation cannot be accounted for by slowed responses, as response times were not changed by stimulation. Our results indicate that left prefrontal anodal stimulation leads to an enhancement of working memory performance. Furthermore, this effect depends on the stimulation polarity and is specific to the site of stimulation. This result may be helpful to develop future interventions aiming at clinical benefits.

A sham stimulation-controlled trial of rTMS of the unaffected hemisphere in stroke patients

The authors investigated the use of slow-frequency repetitive transcranial magnetic stimulation (rTMS) to the unaffected hemisphere to decrease interhemispheric inhibition of the lesioned hemisphere and improve motor function in patients within 12 months of a stroke. Patients showed a significant decrease in simple and choice reaction time and improved performance of the Purdue Pegboard test with their affected hand after rTMS of the motor cortex in the intact hemisphere as compared with sham rTMS.

Repetitive transcranial magnetic stimulation is as effective as fluoxetine in the treatment of depression in patients with Parkinson’s disease

Objective: To study the efficacy of 15 Hz repetitive transcranial magnetic stimulation (rTMS) in treating depression in patients with Parkinson’s disease. Methods: 42 patients were enrolled into two groups: group 1, active rTMS (15 Hz rTMS for 10 days) and placebo drug treatment; group 2, sham rTMS and fluoxetine 20 mg/day. A specially designed sham coil was used for sham stimulation. The unified Parkinson’s disease rating scale (UPDRS), activities of daily living (ADL), Hamilton rating scale for depression (HRSD), Beck depression inventory (BDI), and mini-mental state examination (MMSE) were assessed by a rater blinded to treatment arm. Results: HRSD and BDI were improved to the same extent in both groups after two weeks of treatment (38% and 32% for group 1, 41% and 33% for group 2, respectively). At week 8 there was a tendency for worse motor UPDRS scores in group 2 (NS). ADL showed improvement at week 8 only in group 1. MMSE improved in both groups after treatment, but faster in group 1 than in group 2. There were fewer adverse effects in group 1 than in group 2. Conclusions: rTMS has the same antidepressant efficacy as fluoxetine and may have the additional advantage of some motor improvement and earlier cognitive improvement, with fewer adverse effects.

Transient tinnitus suppression induced by repetitive transcranial magnetic stimulation and transcranial direct current stimulation

Modulation of activity in the left temporoparietal area (LTA) by 10 Hz repetitive transcranial magnetic stimulation (rTMS) results in a transient reduction of tinnitus. We aimed to replicate these results and test whether transcranial direct current stimulation (tDCS) of LTA could yield similar effect. Patients with tinnitus underwent six different types of stimulation in a random order: 10‐Hz rTMS of LTA, 10‐Hz rTMS of mesial parietal cortex, sham rTMS, anodal tDCS of LTA, cathodal tDCS of LTA and sham tDCS. A non‐parametric analysis of variance showed a significant main effect of type of stimulation (P = 0.002) and post hoc tests showed that 10‐Hz rTMS and anodal tDCS of LTA resulted in a significant reduction of tinnitus. These effects were short lasting. These results replicate the findings of the previous study and, in addition, show preliminary evidence that anodal tDCS of LTA induces a similar transient tinnitus reduction as high‐frequency rTMS.

Transcranial magnetic stimulation accelerates the antidepressant effect of amitriptyline in severe depression: A double-blind placebo-controlled study

BACKGROUND Transcranial magnetic stimulation (TMS) is a noninvasive method to stimulate the cortex, and the treatment of depression is one of its potential therapeutic applications. Three recent meta analyses strongly suggest its benefits in the treatment of depression. The present study investigates whether repetitive TMS (rTMS) accelerates the onset of action and increases the therapeutic effects of amitriptyline. METHODS Forty-six outpatients meeting DSM-IV criteria for nonpsychotic depressive episode were randomly assigned to receive rTMS (n = 22) or sham repetitive TMS (sham) (n = 24) during 4 weeks over dorsolateral prefrontal cortex (DLPFC) in this double-blind controlled trial. All patients were concomitantly taking amitriptyline (mean dose 110 mg/d). The rTMS group received 20 sessions (5 sections per week) of 5 Hz rTMS (120% of motor threshold and 1250 pulses per session). Sham stimulation followed the same schedule, however, using a sham coil. The efficacy variables were the Hamilton Depression Rating Scale-17 items (HAM-D/17), the Montgomery-Asberg Depression Rating Scale (MADRS), a Visual Analogue Scale (VAS), and the Clinical Global Impression (CGI). Tolerability was assessed by clinical examination and a safety screening of TMS side effects. RESULTS Repetitive TMS had a significantly faster response to amitriptyline. There was a significant decrease in HAM-D/17 scores, already after the first week of treatment (p < .001 compared with baseline and p < .001 compared with sham). The decrease in HAM-D/17 scores in the rTMS group was significantly superior compared with the sham group throughout the study (p < .001 at fourth week). CONCLUSIONS Repetitive TMS at 5 Hz accelerated the onset of action and augmented the response to amitriptyline.

Effect of repetitive TMS and fluoxetine on cognitive function in patients with parkinson's disease and concurrent depression

Previous studies show that cognitive functions are more impaired in patients with Parkinsons disease (PD) and depression than in nondepressed PD patients. We compared the cognitive effects of two types of antidepressant treatments in PD patients: fluoxetine (20 mg/day) versus repetitive transcranial magnetic stimulation (rTMS, 15 Hz, 110% above motor threshold, 10 daily sessions) of the left dorsolateral prefrontal cortex. Twenty‐five patients with PD and depression were randomly assigned either to Group 1 (active rTMS and placebo medication) or to Group 2 (sham rTMS and fluoxetine). A neuropsychological battery was assessed by a rater blind to treatment arm at baseline and 2 and 8 weeks after treatment. Patients in both groups had a significant improvement of Stroop (colored words and interference card) and Hooper and Wisconsin (perseverative errors) test performances after both treatments. Furthermore, there were no adverse effects after either rTMS or fluoxetine in any neuropsychological test of the cognitive test battery. The results show that rTMS could improve some aspects of cognition in PD patients similar to that of fluoxetine. The mechanisms for this cognitive improvement are unclear, but it is in the context of mood improvement.

Repetitive transcranial magnetic stimulation improve tinnitus in normal hearing patients: a double‐blind controlled, clinical and neuroimaging outcome study

Background and purpose:  Tinnitus is a frequent disorder which is very difficult to treat and there is compelling evidence that tinnitus is associated with functional alterations in the central nervous system. Targeted modulation of tinnitus‐related cortical activity has been proposed as a promising new treatment approach. We aimed to investigate both immediate and long‐term effects of low frequency (1 Hz) repetitive transcranial magnetic stimulation (rTMS) in patients with tinnitus and normal hearing.

Repetitive Transcranial Magnetic Stimulation Is Efficacious as an Add-On to Pharmacological Therapy in Complex Regional Pain Syndrome (CRPS) Type I

UNLABELLED Single-session repetitive transcranial magnetic stimulation (rTMS) of the motor cortex (M1) is effective in the treatment of chronic pain patients, but the analgesic effect of repeated sessions is still unknown. We evaluated the effects of rTMS in patients with refractory pain due to complex regional pain syndrome (CRPS) type I. Twenty-three patients presenting CRPS type I of 1 upper limb were treated with the best medical treatment (analgesics and adjuvant medications, physical therapy) plus 10 daily sessions of either real (r-) or sham (s-) 10 Hz rTMS to the motor cortex (M1). Patients were assessed daily and after 1 week and 3 months after the last session using the Visual Analogical Scale (VAS), the McGill Pain Questionnaire (MPQ), the Health Survey-36 (SF-36), and the Hamilton Depression (HDRS). During treatment there was a significant reduction in the VAS scores favoring the r-rTMS group, mean reduction of 4.65 cm (50.9%) against 2.18 cm (24.7%) in the s-rTMS group. The highest reduction occurred at the tenth session and correlated to improvement in the affective and emotional subscores of the MPQ and SF-36. Real rTMS to the M1 produced analgesic effects and positive changes in affective aspects of pain in CRPS patients during the period of stimulation. PERSPECTIVE This study shows an efficacy of repetitive sessions of high-frequency rTMS as an add-on therapy to refractory CRPS type I patients. It had a positive effect in different aspects of pain (sensory-discriminative and emotional-affective). It opens the perspective for the clinical use of this technique.

Depression in Parkinson's disease: Convergence from voxel-based morphometry and functional magnetic resonance imaging in the limbic thalamus

Depression is the most frequent psychiatric disorder in Parkinsons disease (PD). Although evidence suggests that depression in PD is related to the degenerative process that underlies the disease, further studies are necessary to better understand the neural basis of depression in this population of patients. In order to investigate neuronal alterations underlying the depression in PD, we studied thirty-six patients with idiopathic PD. Twenty of these patients had the diagnosis of major depression disorder and sixteen did not. The two groups were matched for PD motor severity according to Unified Parkinson Disease Rating Scale (UPDRS). First we conducted a functional magnetic resonance imaging (fMRI) using an event-related parametric emotional perception paradigm with test retest design. Our results showed decreased activation in the left mediodorsal (MD) thalamus and in medial prefrontal cortex in PD patients with depression compared to those without depression. Based upon these results and the increased neuron count in MD thalamus found in previous studies, we conducted a region of interest (ROI) guided voxel-based morphometry (VBM) study comparing the thalamic volume. Our results showed an increased volume in mediodorsal thalamic nuclei bilaterally. Converging morphological changes and functional emotional processing in mediodorsal thalamus highlight the importance of limbic thalamus in PD depression. In addition this data supports the link between neurodegenerative alterations and mood regulation.

Antiepileptic effects of repetitive transcranial magnetic stimulation in patients with cortical malformations: an EEG and clinical study.

Objective: To study the effects of repetitive transcranial magnetic stimulation (rTMS) on epileptic EEG discharges in patients with refractory epilepsy and malformations of cortical development (MCDs). Methods: Eight patients with MCD and refractory epilepsy underwent 1 session of low-frequency rTMS (0.5 Hz, 600 pulses) focally targeting the MCD. The number of epileptiform discharges (EDs) in the EEG and seizures were measured before (baseline), immediately after as well as 15 and 30 days after rTMS treatment. Results: Stimulation significantly decreased the number of EDs 15 and 30 days after rTMS treatment (mean reduction of 46.4%, 95% CI 12.7–80.2%, and mean reduction of 42.1%, 95% CI 8.2–75.7%, respectively). This was associated with a significant reduction in the number of seizures reported as compared with the 4-week period preceding rTMS (mean reduction of 57.3%, 95% CI 33.1–80.3%, and mean reduction of 51.2%, 95% CI 27.9–74.9%, respectively). Conclusion: This open study shows a significant antiepileptic effect of rTMS based on clinical and electrophysiological criteria and supports the therapeutic utility of rTMS for patients with well-localized epileptogenic cortical malformations.