The diagnostic value of electroencephalography in mild senile Alzheimer' sdisease

Objective: We investigated the diagnostic value of the visually assessed el ectroencephalogram (EEG) in patients with mild Alzheimer's disease (AD), us ing the grand total of EEG (GTE) score. Methods: Forty-nine non-demented control subjects with and without minimal cognitive impairment from the general population and 86 probable AD patient s (NINCDS-ADRDA criteria), consecutively referred to a memory clinic, parti cipated in this study. Results: Frequency of rhythmic background activity (P < 0.05), diffuse slow activity (P < 0.001), and reactivity of the rhythmic background activity ( P < 0.001) were statistically significant related to the diagnosis control subject or AD patient, using logistic regression analysis with adjustment f or age and sex. When these subscores were used to confirm the diagnosis of AD, thus at high specificity of 89.1% (GTE cut-off point of 3), the sensiti vity was 44.6% and positive predictive value was 88.1%. Incremental ruling- in and ruling-out curves showed a maximum diagnostic gain of 38% for a posi tive test result at a prior probability ranging from 30 to 40%. At high pre test probability levels of 80-90%, the diagnostic gain for a positive test result was low, varying from 7 to 14%. Conclusion: In conclusion, the visually assessed EEG may give a clinically meaningful contribution to the diagnostic evaluation of AD when there is di agnostic doubt. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.