Transcranial direct current stimulation (TdCS) clinical trials have exploded in recent years. This intervention was once reserved to the laboratory setting, or perhaps for military training purposes. Now it is widely available to the consumer and can even be made DIY with a quick trip to the hardware store.
The weak electrical currents from the equivalent of a 9V battery are administered to the scalp in various regions. They exert local effects on the underlying cortex, but also on functionally connected remote regions. Certain areas have been implicated for neuro-stimulation of learning, pain control, and anxiety, among others (1).
First developed for stroke rehabilitation and other types of brain trauma, recent TdCS studies have examined its effect on chronic pain, treatment resistant depression, cerebral palsy, schizophrenia, and eating disorders (1).
Research in Fibromyalgia
Transcranial direct current stimulation (TdCS) has been shown to improve pain symptoms in fibromyalgia in various blinded, clinical trials. The exact mechanisms are still unknown but it is believed to stimulate the release of the inhibitory neurotransmitter GABA and influence other neurotransmitters. Other studies have shown sleep improvements following TdCS, including more frequent REM cycles and longer duration of sleep (2).
Risk vs Benefits
The exact mechanisms in which TdCS effects the brain is mostly unknown. The research is mixed as to whether it increases neuronal plasticity through growth factors such as BDNF. There is also little known about the “proper” application and duration of treatment (3).
Some studies have shown positive effects on learning and memory only when the stimulation occurs while doing a task. No follow-up studies are available to determine the long term or lasting effects of TdCS. Some TdCS users experience mild side effects such as headache, skin irritation under the electrodes, or over stimulation (3). However, it has been noted that TdCS use gives considerably fewer side effects compared to FDA approved fibromyalgia drugs (4).
How about TdCS for the ME/CFS Brain?
Studies using fMRI and other advanced brain imaging techniques demonstrated increased cerebral blood flow during TdCS. This is thought to be due to stimulation of glial cells in the brain—specifically astrocytes which regulate much of cerebral blood flow (5). Similar advanced imaging studies have demonstrated widespread hypoperfusion (decreased blood flow) to the brain in ME/CFS patients (6). Neuro-stimulation with TdCS may be a viable intervention to improve cerebral blood flow in some patients, with the potential to reduce cognitive symptoms.
1 Foerster BR, et al (2014) Excitatory and Inhibitory Brain Metabolites as Targets and Predictors of Effective Motor Cortex tDCS Therapy in Fibromyalgia. Arthritis Rheumatol. http://www.ncbi.nlm.nih.gov/pubmed/25371383
2 Roizenblatt S, et al. (2007) Site-specific effects of transcranial direct current stimulation on sleep and pain in fibromyalgia: a randomized, sham-controlled study. Pain Pract. 7(4):297-306. Epub 2007 Nov 6. http://www.ncbi.nlm.nih.gov/pubmed/17986164
3 Berryhill ME, etl al (2014) Hits and misses: leveraging tDCS to advance cognitive research. Front Psychol. 5:800. http://www.ncbi.nlm.nih.gov/pubmed/25120513
4 Marlow NM, Bonilha HS, Short EB. (2013) Efficacy of transcranial direct current stimulation and repetitive transcranial magnetic stimulation for treating fibromyalgia syndrome: a systematic review. Pain Pract. 13(2):131-45. http://www.ncbi.nlm.nih.gov/pubmed/22631436
5 Nord CL, Lally N, Charpentier CJ (2013) Harnessing electric potential: DLPFC tDCS induces widespread brain perfusion changes. Front Syst Neurosci. 7:99. http://www.ncbi.nlm.nih.gov/pubmed/24348348
6 Yoshiuchi K, Farkas J, Natelson BH. (2006) Patients with chronic fatigue syndrome have reduced absolute cortical blood flow. Clin Physiol Funct Imaging. 26(2):83-6. http://www.ncbi.nlm.nih.gov/pubmed/16494597