The effect of anodal high definition transcranial direct current stimulation on the pain sensitivity in a healthy population: a double-blind, sham-controlled study.
ABSTRACT: High-definition transcranial direct current stimulation (HD- tDCS) of brain areas related to pain processing may provide analgesic effects evident in the sensory detection and pain thresholds. The somatosensory sensitivity was assessed following HD- tDCS targeting the primary motor cortex (M1) and/or the dorsolateral prefrontal cortex (DLPFC). Eighty-one (40 females) subjects were randomly assigned to one of four anodal HD- tDCS protocols (20 min) applied on three consecutive days: Sham- tDCS, DLPFC- tDCS, M1- tDCS, and DLPFC&M1- tDCS (simultaneous tDCS of DLPFC and M1). Subjects and experimenter were blinded to the tDCS protocols. The somatosensory sensitivity were assessed each day, before and after each tDCS by detection and pain thresholds to thermal and mechanical skin stimulation, vibration detection thresholds, and pressure pain thresholds. Subjects were effectively blinded to the protocol, with no significant difference in rates of whether they received real or placebo tDCS between the four groups. Compared with the Sham-tDCS, none of the active HD-tDCS protocols caused significant changes in detection or pain thresholds. Independent of tDCS protocols, pain and detection thresholds except vibration detection were increased immediately after the first tDCS protocol compared with baseline (P <0.05). Overall, the active stimulation protocols were not able to induce significant modulation of the somatosensory thresholds in this healthy population compared to sham-tDCS. Unrelated to the HD-tDCS protocol a decreased sensitivity was found after the first intervention, indicating a placebo effect or possibly habituation to the QST assessments. These findings add to the increasing literature of null-findings in the modulatory effects of HD-tDCS on the healthy somatosensory system.
PMID: 33449508 [PubMed – as supplied by publisher]
Pain. 2021 Jan 11;:
Authors: Kold S, Graven-Nielsen T