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P2–069: Index of alpha/theta ratio of the electroencephalogram: A new marker for Alzheimer's disease
Author(s) -
Schmidt Magali,
Kanda Paulo,
Oliveira Helder,
Baratho Regina,
Jorge Mario,
Nitrini Ricardo,
Anghinah Renato
Publication year - 2013
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2013.05.712
Subject(s) - neurology , electroencephalography , logistic regression , alzheimer's disease , outpatient clinic , alpha (finance) , medicine , psychology , disease , audiology , neuroscience , psychometrics , clinical psychology , construct validity
Background: The inclusion of electroencephalography in diagnostic research protocols for AD is fully justified given EEG’s wide availability, low cost and high sensitivity, allowing serial exams and neurological evolution follow-ups. Objective: To determine a screening index for use in routine clinical practice to aid the diagnosis of Alzheimer’s disease (AD).Methods: Two groups of individuals older than 50 years, comprising a control group of 57 normal volunteers and a study group of 50 patients with probable AD, were compared. All were recruited from Outpatient Clinic of the Cognitive and Behavioral Neurology Group (GNCC) of the Division of Clinical Neurology of the HCFMUSP(Clinics Hospital of Medicine School of University of S~ao Paulo) and/or from the CEREDIC (Referral Center for CognitiveDisorders) of the HCFMUSP, who were submitted to routine outpatient assessment for diagnosing Alzheimer disease. EEG recordings were performed of subjects in a wake state with eyes closed at rest for 30 mins. Spectral potentials of the alpha and theta bands were computed separately for all electrodes and all electroencephalograms. Subsequently, the alpha/theta ratio between these spectral potentials was calculated. Thus, a total of 20 electrodes common to the whole sample were analyzed. Correlation analysis and crossing of the alpha/theta ratio of the Mean Potential with the Alzheimer disease variable was carried out, followed by logistic regression analysis and obtention of the ROC curve. Results: Spectral potentials of the alpha and theta bands were computed and the alpha/theta ratio calculated. Logistic regression of the variables alpha/theta of the mean potential of the C3 and O1 electrodes was carried out. A formula was calculated to aid the diagnosis of AD yielding 76.4 % sensitivity and 84,6 specificity for AD with an area under the ROC curve of 0.92. Multiply alpha/theta of mean potential of C3 electrode by 18 Multiply alpha/theta of mean potential of O1 electrode by 12 Sum the two values A result of less than 33 indicates dementia else no dementia.Conclusions: Logistic regression of the alpha/theta of the Spectrum of the mean potential of EEG represents a good marker for discriminating between AD patients and normal controls.