For a study, researchers sought to determine whether non-invasive brain stimulation with transcranial alternating current stimulation at gamma-frequency (γ-tACS) applied over the precuneus can enhance episodic memory and regulate cholinergic transmission by altering cerebral rhythms in early Alzheimer’s disease (AD); this study set out to examine these effects. In this randomized, double-blind, sham-controlled, crossover study, 60 AD patients underwent a clinical and neurophysiological evaluation, including an assessment of episodic memory and cholinergic transmission before and after receiving either a sham tACS or a 60-minute treatment with γ-tACS targeting the precuneus. EEG analysis and customized electric field distribution modeling were done on a subset of 10 patients. Evaluation of predictors for γ-tACS efficacy. They noticed a huge improvement in the Rey Auditory Verbal Learning (RAVL) test quick review (P<0.001) and deferred review scores (P<0.001) later γ-tACS, however not after hoax tACS. Face-name affiliations scores improved with γ-tACS (P<0.001) yet not after joke tACS. Short dormancy afferent restraint, a backhanded proportion of cholinergic transmission, expanded solely after γ-tACS (P<0.001). ApoE genotype and benchmark mental hindrance were the best reaction indicators to γ-tACS. Clinical improvement was connected with the expansion in gamma frequencies in back locales and with how much anticipated electric field dissemination in the precuneus. Precuneus γ-tACS, ready to increment γ-power action on the back cerebrum districts, showed a critical improvement of verbose memory exhibitions, alongside reclamation of intracortical sensitivity proportions of cholinergic transmission. Reaction to γ-tACS was subject to genetic elements and illness stage. 

Source: onlinelibrary.wiley.com/doi/10.1002/ana.26411