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Modulating Cognition Using Transcranial Direct Current Stimulation of the Cerebellum
Published on: February 15, 2015
High definition transcranial direct current stimulation as an intervention for cognitive deficits in Alzheimer's
Christian LoBue1, Hsueh-Sheng Chiang2, Amber Salter2
1Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Neurological Surgery, University of Texas Southwestern Medical Center, Dallas, TX, USA.
Background:
Recent disease-modifying treatments for Alzheimer's disease show promise to slow cognitive decline, but show no efficacy towards reducing symptoms already manifested.
Objectives:
To investigate the efficacy of a novel noninvasive brain stimulation technique in modulating cognitive functioning in Alzheimer's dementia (AD).
Design:
Pilot, randomized, double-blind, parallel, sham-controlled study SETTING: Clinical research site at UT Southwestern Medical Center PARTICIPANTS: Twenty-five participants with clinical diagnoses of AD were enrolled from cognition specialty clinics.
Intervention:
Treatment consisted of high definition transcranial direct current stimulation (HD-tDCS) delivered for 20 min over the medial prefrontal cortex. Ten sessions of sham, 1 mA, or 2 mA stimulation were received.
Measurements:
Cognitive outcomes were measured at baseline, after the last HD-tDCS session, and 8-weeks post-treatment. The primary outcome was change in total learning and delayed recall on the Rey Auditory Verbal Learning Test (RAVLT) immediately post-treatment and at 8-weeks. Secondary outcomes included measures of language, processing speed, and executive functioning. A multi-stage approach was used to examine cognitive outcomes, which included evaluation of effect sizes, statistical effects, and rate of clinically meaningful responses.
Results:
In this pilot trial, no statistically significant differences on cognitive outcomes were found between sham and active HD-tDCS immediately post-treatment (p's > 0.05). However, moderate-to-large effect sizes were identified for enhanced RAVLT total learning (Cohen's d = 0.69-0.93) and phonemic fluency (d = 1.08-1.49) for both active HD-tDCS conditions compared to sham, with rates of clinically relevant improvement between 25 and 33%. Meaningful enhancement persisted to 8 weeks only for the 1 mA condition.
Conclusions:
Multiple sessions of HD-tDCS over the medial prefrontal cortex appears to have potential to produce meaningful cognitive enhancements in a proportion of patients having AD with improvements maintained for at least 8 weeks in some.
Trial Registration Information:
ClinicalTrials.gov (NCT05270408). Registered December 30, 2021.
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