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IC–P–046: Magnetoencephalography (MEG) parietal delta dipole density in mild cognitive impairment: Preliminary results of a method to estimate the risk of developing Alzheimer's disease
Author(s) -
Fernández Alberto,
Turrero Agustı́n,
Zuluaga Pilar,
Gil-Gregorio Pedro,
Maestu Fernando,
Campo Pablo,
Ortiz Tomas
Publication year - 2006
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.2006.05.2251
Subject(s) - magnetoencephalography , cognitive impairment , psychology , audiology , alzheimer's disease , cognition , cohort , disease , posterior parietal cortex , medicine , electroencephalography , cardiology , neuroscience
Background: Subjects with mild cognitive impairment (MCI) are at higher risk of suffering from Alzheimer’s disease (AD). Previous investigation (Fernández et al, 2002; 2003; 2005) demonstrated that MEG temporoparietal dipole densities of low-frequency activity are good predictors of individuals’ cognitive status, and might be a useful tool to investigate the conversion from MCI to AD. Objective(s): We investigated the role of low-frequency dipole densities as predictors of risk of developing AD. Methods: Whole-head magnetoencephalographic recordings were obtained from 19 probable AD patients, 17 MCI patients, and 17 healthy control subjects. The generators of focal magnetic slow waves were located employing a single moving dipole model. Results: Left parietal delta dipole density (LPD) permitted a reliable classification of AD and MCI patients (sensitivity was 0.737, specificity 0.765, and total classification accuracy was 75.0%), while right occipital dipole density permitted a reliable classification of MCI patients and controls (sensitivity was 0.706, specificity 0.882, and total classification accuracy was 79.4%). Once LPD was confirmed as a reliable variable for the classification of AD and MCI patients a follow-up study was performed. The 17 MCI patients were followed for two years, with a clinical evaluation every 6 months; no loss to follow-up occurred. The cohort was divided into two groups based on a median split of the LPD measure: MCI-High, and MCI-Low. The two groups of MCI patients did not differ in terms of age or MMS score at baseline. After two years 5/17 patients (29.41%) met criteria for Probable AD. MMSE scores were significantly (p 0.042) reduced (8.8 7.01 points) in the converter group from baseline. Four of the 8 (50%) MCIHigh patients developed AD, while only 1 out of 9 (11%) MCI-Low patients converted to dementia (RR 4.5, 95% CI .86 28.3). The estimated relative risk of conversion to AD was increased by 350% in those MCI patients with high LPD scores (MCI-High group). Conclusions: Results confirmed the important role of parietal delta dipole density in the evaluation of AD and MCI. A MEG-based assessment of AD and MCI patients might be considered a useful clinical test in the near future.