Transcranial Alternating Current Stimulation on Patients with Delirium and Critical Illness: a Randomized, Controlled, Double Blind, Proof-of-concept Pilot Study

Delirium is an acute-onset brain dysfunction related to extensive surgery or critical illness that leads to altered mental status and cognitive deficits. Delirium is associated with an increased length of stay in the ICU, cost of care, excessive mortality, and long-term cognitive and functional impairment. Although numerous prophylactic methods have been proposed, currently, no pharmacological or non-pharmacological methods are clinically effective. Patients with delirium have altered electroencephalography (EEG) findings among which most important are general slowing of EEG frequencies and dysconnectivity. Faster EEG frequencies, especially alpha-, beta-, and gamma-bands, are correlated with higher cognitive functions, such as memory and orientation. Transcranial alternating current stimulation (TACS) is a novel, noninvasive brain stimulation technology that cab modulate EEG frequencies by entraining of endogenous brain oscillations in response to exogenous stimuli. TACS has been shown to improve episodic memory, orientation, and cholinergic dysfunction in patients with Alzheimer's disease. TACS also increases alpha and gamma frequencies in EEG, and an increase in these frequencies is associated with the improvement of clinical symptoms. TACS has been shown to target key components of delirium pathophysiology, such as slowing of EEG frequencies and cholinergic dysfunction. Thus, we hypothesized that TACS could shorten the duration of delirium and decrease cognitive decline. We aim to test this hypothesis in a double-blind randomized trial and assess the effect of TACS on duration of delirium, EEG, biomarkers and long-term cognition.