Home-Based Closed-Loop Auditory Stimulation to Enhance Slow-Wave Activity in MCI Due to Alzheimer's Disease: A Proof-of-Concept Study

This proof-of-concept study explores whether long-term home-based closed-loop auditory stimulation during sleep enhances slow-wave activity (SWA) and yields preliminary efficacy signals in patients with amnestic mild cognitive impairment due to Alzheimer's disease (MCI-AD), confirmed by cerebrospinal fluid (CSF) biomarkers or positron emission tomography (PET). The intervention is self-administered at participants' homes over an initial treatment period of 3 months, followed by a 1-month off-treatment (washout) period. Participants may then enter an optional extension phase consisting of 3 additional months of treatment followed by a second 1-month washout period, for a total study duration of up to 8 months. Participants who complete the Nana-Lab Study (NCT07402590) may be invited to provide informed consent for screening and potential enrollment in this study. All enrolled participants receive nightly active treatment during intervention periods. This study does not include randomization or a sham control group.

Inclusion criteria: * Age between 50 and 75 years (inclusive). * Spanish as native language. * Diagnosis of amnestic mild cognitive impairment due to Alzheimer's disease, confirmed by cerebrospinal fluid biomarkers or amyloid PET. * Normal or corrected-to-normal color vision (required for completion of visual-analog study assessments). * Adequate hearing to perceive the auditory stimuli used in the intervention, defined as a hearing threshold of 50 dB or below, assessed during the screening session. Exclusion criteria: * Severe systemic or complex chronic disease that, in the investigator's judgment, would compromise participant safety or data quality, including but not limited to: advanced heart disease; advanced chronic kidney disease (stage 4 or 5); severe pulmonary disease (e.g., COPD GOLD stage III-IV); metastatic or terminal cancer; severe hematological disorders; or active or uncontrolled chronic infectious disease (e.g., untreated HIV). * Evidence on neuroimaging of strategic infarcts or other findings that may account for secondary cognitive impairment. * Alcohol or psychotropic substance abuse. * Diagnosis of depression or any severe psychiatric disorder within the 5 years prior to evaluation. * Changes in benzodiazepine or antidepressant treatment within the 6 months prior to baseline evaluation. * Current treatment with neuroleptics. * Epilepsy with active treatment within the last 5 years, or any neurological comorbidity that may cause cognitive impairment or structural brain damage. * Unable to read and write in Spanish. * Inability to use the study device effectively, as determined during the screening session. This includes, but is not limited to, anatomical or dermatological factors preventing adequate electrode placement, or excessive EEG signal artifacts that prevent reliable detection of sleep oscillations.