Tele‐supervised home‐based transcranial alternating current stimulation (tACS) for Alzheimer’s disease

Abstract

AbstractBackgroundOver 55 million people worldwide are currently diagnosed with Alzheimer’s disease (AD) and live with debilitating episodic memory deficits (World Health Organization, 2022). Current pharmacological treatments have limited efficacy. Recently, transcranial alternating current stimulation (tACS) has shown memory improvement in AD by normalizing high‐frequency neuronal activity (Benussi et al., 2022). Our goal was to assess the safety, feasibility, and preliminary effects on episodic memory of a caregiver‐led home‐based tACS approach (HB‐tACS).Method8 participants diagnosed with AD (Table 1) underwent high‐definition HB‐tACS (40 Hz, 20‐minutes) targeting the left angular gyrus (AG), a key node of the memory network. The Acute Phase comprised 14‐weeks of HB‐tACS with at least five weekly sessions. Three participants underwent resting‐state electroencephalography (EEG) before and after. Subsequently, participants completed a 2–3‐month Hiatus Phase not receiving tACS. In the Taper Phase, participants received 2‐3 sessions per week over 3‐months. Primary outcomes were memory and global cognition, measured with the Memory Index Score (MIS) and Montreal Cognitive Assessment (MoCA), respectively, and EEG theta/gamma ratio. Results reported as mean±SD.ResultAll participants completed the study with, on average, 97 HB‐tACS sessions; reporting mild side effects during 25% of sessions, moderate during 5%, and severe during 1%. Acute Phase adherence was 98±6.8% and Taper Phase was 125±22.3% (from minimum of 2/week). After the Acute Phase, all participants showed memory improvement, MIS of 7.25±3.77, sustained during Hiatus 7.00±4.90 and Taper 4.63±2.39 Phases (Table 2), and decreased theta/gamma ratio in AG (Figure 1A). Conversely, participants did not show improvement in the MoCA, 1.13±3.80 after the Acute Phase, and there was modest decrease during the Hiatus ‐0.64± 3.28 and Taper ‐2.56±5.03 phases. These results suggest the specificity of the intervention for memory functioning (Figure 1B) and relate improvement to decreased theta/gamma ratio.ConclusionThis pilot study shows the feasibility of a novel, remotely supervised, caregiver‐led HB‐tACS intervention for AD. Targeting the left AG, memory was noticeably improved while global cognition was relatively stable, indicating that future interventions might benefit from multifocal neuromodulation targeting multiple cognitive domains. These results are encouraging for the prospect of safe and feasible treatment within patients’ homes.