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

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

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.

Study Overview

• Status: Completed
• Conditions: Alzheimer Disease, Early Onset
• Intervention / Treatment: Diagnostic test: CSF

Detailed Description

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.

• Study Type: Observational
• Enrollment (Actual): 51

Contacts and Locations

Study Locations

• Turkey
  • İzmir, Turkey
    • Izmir University of Economics

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

The present study included a retrospective investigation of EEG and MRI data. The total sample for the study consisted of 24 early-onset Alzheimer's disease patients and 24 healthy controls.

Description

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)

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Healthy controls; Age-and gender-matched healthy volunteers were recruited via advertisements and word-of-mouth.
Early-onset Alzheimer's disease; 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; Early-onset Alzheimer's disease patients underwent routine laboratory tests to obtain CSF samples. Also, all participants underwent structural MRI examinations and neuropsychological tests.; Other Names: MRI; Neuropsychological tests

What is the study measuring?

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
Discriminant Analysis	The discriminative power of gamma measures (power and coherence) was investigated with discriminant analysis (DA).	3 months
Correlation Analysis	Correlations between CSF, neuropsychological tests (NPT), EEG, and MRI measures were investigated.	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

Collaborators and Investigators

• Sponsor: Görsev Yener, MD, PhD

Study record dates

Study Major Dates

• Study Start (Actual): November 7, 2012
• Primary Completion (Actual): January 2, 2016
• Study Completion (Actual): April 5, 2019

Study Registration Dates

• First Submitted: July 25, 2023
• First Submitted That Met QC Criteria: August 2, 2023
• First Posted (Actual): August 14, 2023

Study Record Updates

• Last Update Posted (Actual): August 22, 2023
• Last Update Submitted That Met QC Criteria: August 17, 2023
• Last Verified: August 1, 2023

More Information

Terms related to this study

• Keywords: MRI; Alzheimer's disease; Gamma activity; Resting-state EEG; Discriminative power
• Additional Relevant MeSH Terms: Mental Disorders; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Neurocognitive Disorders; Neurodegenerative Diseases; Dementia; Tauopathies; Alzheimer Disease
• Other Study ID Numbers: DokuzEU EEG

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: The data that support the findings of this study are available from the contact person, upon reasonable request.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No