Effects of Auditory Brain Stimulation by "Pink Noise" on Memory Capacities in Alzheimer's Disease: Proof of Concept Study

Alzheimer's disease (AD) is a neurodegenerative disorder affecting almost 6% of the world's population over the age of 65. This disease, in its most typical sporadic form, is characterized by an episodic memory impairment linked to a deficit in consolidation. Many studies indicate that sleep promotes this consolidation stage during the deep slow sleep stage by facilitating the transfer of information between the hippocampus and the neocortex.

A method of acoustic brain stimulation at night by pink noises has been recently developed and has shown its effectiveness in strengthening memory consolidation in healthy volunteers. Actually, there is no study observing the effect of this new stimulation method on populations with neurodegenerative pathologies, in particular in AD for which this technique could potentially become a therapeutic option.

The hypothesis is that of a strengthening of the memory consolidation capacities in subjects with AD as has been shown in healthy subjects.

Inclusion criteria

common to all participants:

• Age> 50 years at the inclusion
• Patient with regular sleep patterns
• Patient having given written consent
• Patient affiliated to a social security regimen

Inclusion criteria

for subjects with Alzheimer's disease:

• Patient with a beginning Alzheimer's disease defined according to the criteria of the National Institute on Aging-Alzheimer's Association or carriers of a prodromal Alzheimer's disease defined according to the criteria of the International Working Group IWG-2; the diagnosis must be supported by brain imaging and a blood test carried out in routine care
• MMSE score ≥ 24

Inclusion criteria

for healthy volunteers:

• Absence of neurodegenerative pathologies
• Matched in age (+/- 5 years) and in sex with a patient

Non-inclusion criteria common to all participants:

• Psychiatric pathologies (except depression or anxiety disorders stabilized for more than 3 months)
• History of pathology which may have consequences on cognitive functioning and / or sleep: brain tumor, constituted stroke, epilepsy, head trauma (with clinical or parenchymal sequelae objectified on brain imagery), brain surgery
• Any significant comorbidity likely to constitute a confounding factor according to the clinician
• Psychotropic treatments introduced or modified <3 months before inclusion
• Hypnotic and / or sedative treatments
• Chronic consumption of alcohol or drugs
• Legal incapacity and / or other circumstance rendering the patient unable to understand the nature, objective or consequences of the study
• Major under guardianship or curatorship
• Patient not French-speaking by birth or illiterate

Exclusion criteria

common to all participants:

• Sleep disorders defined by a score> 5 on the Pittsburg sleep quality index (PSQI)
• A score> 10 on the Epworth sleepiness index