Preliminary Outcomes on Depression Symptoms in a Randomized Controlled Trial of High-Definition Transcranial Direct Current Stimulation in Alzheimer's Dementia

New treatments to manage emotional and cognitive symptoms of Alzheimer's Dementia (ad) are needed. High-definition transcranial direct current stimulation (HD-tDCS) is a non-invasive neuromodulation technology with potential as a new treatment for improving neuropsychiatric symptoms. The dorsal anterior cingulate cortex (dACC) is a region found to play an important role in emotional processes and is vulnerable to degeneration in ad. As such, we conducted a pilot study investigating the effect of HD-tDCS applied over the dACC on depression symptoms in ad patients.Ten participants (M age = 71.50, SD = 9.80) with clinically diagnosed mild-to-moderate ad were randomized to receive sham (0 milliamps [mA]; n = 2), 1 mA (n = 5), or 2 mA (n = 3) HD-tDCS for ten daily 20-minute sessions across two weeks. The Beck Depression Inventory-2 (BDI-2) was administered before and after ten treatments. A one-tailed analysis of covariance (ANCOVA) was conducted to examine differences in post-treatment scores between HD-tDCS groups, adjusting for pre-treatment scores.Baseline BDI-2 scores were similar for the groups receiving 1 mA (M = 7.00; SD = 3.10), 2 mA (M = 4.70; SD = 8.10), and sham (M = 9.00; SD = 7.10) Statistically significant differences were found between groups on depression scores after HD-tDCS, F(2) = 3.55, p = 0.048, ηp2 = 0.54), driven by the depression scores in the 1 mA group being lower than the sham group.Our pilot results suggest that HD-tDCS may be associated with a reduction in depression symptoms in ad, though determining the minimum clinically important difference for a decrease needs further evaluation. Future research having larger samples with ad and long-term follow up is also warranted to examine clinical efficacy.