The Resting-state EEG Gamma Oscillations in Alzheimer's Disease

Study Overview
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Brief Summary
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The literature suggests a strong association between amyloid accumulation and gamma alterations, emerging gamma activity as a biomarker candidate for Alzheimer's pathology. The present study aims to investigate resting-state gamma activity changes in Cerebrospinal fluid (CSF)-proven early-onset Alzheimer's disease (EOAD) patients with a holistic approach that employs structural and functional brain neuroimaging techniques, and neuropsychological aspects.

Detailed Description
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This cross-sectional study included 24 drug-naive CSF-proven EOAD patients and age-, sex, and education-matched healthy controls. All participants underwent a detailed neuropsychological evaluation, resting-state electroencephalography (EEG) recording, and Magnetic Resonance Imaging (MRI). Gamma power and coherence were measured in total gamma (30-48 Hz), gamma-1 (30-35 Hz), gamma-2 (35-40 Hz), and gamma-3 (40-48 Hz) frequency bands. Gray matter volumes were extracted for 54 regions of interest (ROIs) and compared between groups. Discriminant analysis was performed to determine the classification accuracy of gamma activity for EOAD. Finally, correlations between CSF, neuropsychological tests, EEG, and MRI measures were explored.

Official Title
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The Underestimated Utility of Resting-state Gamma Oscillations: Both Increase and Decrease of Gamma Discriminates Early-onset Alzheimer's Disease Patients From Healthy Individuals

Conditions
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Alzheimer Disease, Early Onset

Intervention / Treatment
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* Diagnostic Test: CSF


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: For all participants: Age < 65 For EOAD patients: Meeting National Institute on Aging-Alzheimer's Association diagnostic criteria. For healthy controls: Mini-Mental State Examination (MMSE) >25 Instrumental Activities of Daily Living Scale (IADL) = 8 Exclusion Criteria: For EOAD patients: MMSE > 24 Geriatric depression scale (GDS) > 14 Having treatment with antipsychotics and comorbidities that may affect cognitive abilities. For healthy controls: Having neurological and/or cognitive abnormalities Having a history of neurological, psychiatric, or systemic disorders, and alcohol/drug abuse. GDS > 14 For all participants: Having neurological (other than AD) or any other serious disease (cancer, systemic disease)

Ages Eligible for Study
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Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Early-onset Alzheimer's disease<br>Patients were recruited from the outpatient memory clinics of the Department of Neurology, Dokuz Eylül University Hospital. The patient group was diagnosed by an expert neurologist, according to the National Institute on Aging-Alzheimer's Association diagnostic criteria for Alzheimer's disease | Diagnostic Test: CSF<br>* Early-onset Alzheimer's disease patients underwent routine laboratory tests to obtain CSF samples. Also, all participants underwent structural MRI examinations and neuropsychological tests.<br>* Other names: Neuropsychological tests;|
| Healthy controls<br>Age-and gender-matched healthy volunteers were recruited via advertisements and word-of-mouth. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| EEG | The resting state EEG recordings were acquired using Easy-Cap comprising 30 Ag/AgCl electrodes placed according to the international 10-20 system. Coherence and maximum peak power of the total gamma (30-48 Hz) and sub-gamma bands [gamma-1 (30-35 Hz), gamma-2 (35-40 Hz), and gamma-3 (40-48 Hz)] were measured for each participant. | Day 2 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Correlation Analysis | Correlations between CSF, neuropsychological tests (NPT), EEG, and MRI measures were investigated. | 3 months | 
| Discriminant Analysis | The discriminative power of gamma measures (power and coherence) was investigated with discriminant analysis (DA). | 3 months | 
| MRI | Participants underwent structural magnetic resonance imaging on a Philips Achieva 1.5 Tesla scanner. The gray matter volumes were obtained from the 3D-T1 weighted Turbo field echo (TFE) sequence (TR: 9ms, Time to Echo (TE): 4ms, Field-of-view (FOV): 240mm, matrix: 256, slice thickness: 1mm, numbers of signal averages (NSA): 1). The images were segmented into gray matter, white matter, and CSF with the default parameters of the CAT12 segmentation function. Only the gray matter calculations were compared between groups. | Day 1 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Alzheimer's disease, Gamma activity, Resting-state EEG, Discriminative power, MRI