Transcranial Alternating Current Stimulation (tACS) Combined With Cognitive Training in Alzheimer's Disease

The aim of the study is to evaluate the clinical and biological efficacy, as well as predictors of efficacy, of a home-based intervention combining transcranial alternating current stimulation (tACS) with individualized computerized cognitive training in patients with mild Alzheimer's disease (AD).

In neurodegenerative diseases, including AD, neurodegeneration is accompanied by alterations in brain oscillatory activity. Restoration of these oscillations through neuronal entrainment has shown beneficial effects in animal models, while previous studies in patients with AD have demonstrated that gamma-frequency tACS applied over the precuneus is safe and well tolerated and is associated with improvements in cognitive performance and cholinergic function, as well as modulation of brain oscillatory activity. Cognitive rehabilitation may also improve memory performance in patients with mild AD. Based on this evidence, the present study investigates a multimodal approach combining gamma-tACS with individualized computerized memory training.

The study is a multicenter, randomized, placebo-controlled, double-blind trial involving 30 participants with mild AD. Participants will be randomly assigned to one of two groups: Group 1 will receive real gamma-tACS for 8 weeks (5 sessions/week, 60 minutes/session) combined with cognitive training (2 sessions/week, 30 minutes/session); Group 2 will receive sham tACS according to the same schedule, combined with the same cognitive training. tACS will be applied over the precuneus. Treatment will initially be performed in the hospital and will subsequently be administered at home under remote supervision by the study team.

Assessments will be performed at baseline (T00), after 8 weeks of treatment (T08), and at follow-up visits at 16 weeks (T16) and 24 weeks (T24) from baseline. At each time point, participants will undergo clinical and neuropsychological assessment, blood sampling, and transcranial magnetic stimulation (TMS). The occurrence of adverse events will be monitored throughout the duration of the study.

The main objectives of the study are: 1) to evaluate the short- and long-term effects of the combined intervention on cognitive performance; 2) to investigate intervention-induced changes in biological markers of neurodegeneration, inflammation, and synaptic function; 3) to evaluate the effects of the intervention on cholinergic transmission through the TMS short-latency afferent inhibition (SAI) measure; and 4) to investigate potential predictors of treatment efficacy.