Safety – Transcranial direct current stimulation tDCS

Excellent overview article on tDCS from University of Munich who have a research group devoted to Transcranial brain stimulation and neuroplasticity.

Safety of the method
Several studies have been performed on the safety of tDCS and on side effects and have resulted in clear recommendations on its safe use. There is general agreement that if attention is paid to recommendations concerning contraindications and stimulation parameters, tDCS is a well tolerated method with minimal side effects Nitsche et al. 2003, Fregni et al. 2006, Iyer et al. 2005.
The physiological changes involve the modulation of spontaneous neuronal activity through polarity-specific shifts of the resting membrane potential in the direction of de- or hyperpolarisation. The direction of the change is governed by the direction of current flow, the spatial orientation of the neuron, the type of neuron and the total charge. This underlies the possible complication of inducing an epileptic seizure. In accordance with the safety protocol from Nitsche and Paulus 2000, the stimulation charges used here lie far below the charges necessary to trigger a seizure. Even a continuous stimulation just below the energy threshold for triggering a seizure was associated with only a 40% increased cortical excitability compared with baseline. Studies on the question of whether neuronal damage can be observed after tDCS and whether structural changes occur in the brain revealed no indications of damaging effects of tDCS. Thus, levels of neuron-specific enolase NSE, a marker for neuronal destruction, were not increased after tDCS Nitsche et al. 2003 and pathological changes could not be found in either contrast-enhanced MRT or in EEG Nitsche 2003.
Persistent disorders of motor and cognitive abilities have not been found. Electrically induced local muscle contractions during the stimulation can be unpleasant for the person undergoing tDCS. The electrical stimulation causes irritation of the scalp lasting just a few seconds, which has been described as more or less painful tingling and pulling Fregni et al. 2006. Cortical tissue damage has not been found, even after high stimulation intensities and frequencies. Stimulation with electrodes on the scalp could indeed result in a chemical reaction and in burning of the skin tissue. However, the risk of a skin burn is minimised if sponge electrodes soaked in salt water are used, in accordance with the safety protocol of Nitsche and Paulus 2000.
Fregni et al. did not describe any side effects in their studies Bip Disorders 2006, Clin Neurophysiol 2006, Depr and Anx 2006; the treatment was well tolerated by all the patients.

via Transcranial direct current stimulation tDCS.


Most of us are attracted to the idea of DIY tDCS because of the low entry barrier – a nine volt battery and a simple circuit (at least in theroy). But also because so much of the science literature coming out around tDCS hints at exciting possibilities for enhancing our cognitive abilities. The thought of DIY TMS, with it’s high voltages never occurred to me. I was shocked! to find these videos of DIYer Ben Krasnow on Youtube.
HatTip to Marom Bikson, this came to me by way of his Twitter @MaromBikson


Transcranial Direct Current Stimulation Intensity and Duration Effects on Tinnitus Suppression

Tinnitus has been a part of my life for so long I can’t remember not having it. While it doesn’t seem to bother me the way it does others, it can be very annoying, especially when I’m in a very quiet environment, camping for instance. So it would be incredible if a breakthrough in tinnitus treatment were to come along.

Background. Perception of sound in the absence of an external auditory source is called tinnitus, which may negatively affect quality of life. Anodal transcranial direct current stimulation tDCS of the left temporoparietal area LTA was explored for tinnitus relief. Objective. This pilot study examined tDCS dose current intensity and duration and response effects for tinnitus suppression. Methods. Twenty-five participants with chronic tinnitus and a mean age of 54 years took part. Anodal tDCS of LTA was carried out. Current intensity 1 mA and 2 mA and duration 10 minutes, 15 minutes, and 20 minutes were varied and their impact on tinnitus measured. Results. tDCS was well tolerated. Fifty-six percent of participants 14 experienced transient suppression of tinnitus, and 44% of participants 11 experienced long-term improvement of symptoms overnight—less annoyance, more relaxed, and better sleep. There was an interaction between duration and intensity of the stimulus on the change in rated loudness of tinnitus, F2, 48 = 4.355, P = .018, and clinical global improvement score, F2, 48 = 3.193, P = .050, after stimulation. Conclusions. Current intensity of 2 mA for 20 minutes was the more effective stimulus parameter for anodal tDCS of LTA. tDCS can be a potential clinical tool for reduction of tinnitus, although longer term trials are needed.

Again, this study begs the question: If 2 mA was more effective than 1 mA, why not 3?
P.S. Thanks you know who you are!

via Transcranial Direct Current Stimulation Intensity and Duration Effects on Tinnitus Suppression.