Short communication The electroencephalogram in dementia with Lewy bodies Barber PA, Varma AR, Lloyd JJ, Haworth B, Snowden JS, Neary D. The electroencephalogram in dementia with Lewy bodies. Acta Neurol Scand 2000: 101: 53±56. # Munksgaard 2000. Objectives ± Dementia with Lewy bodies (DLB) is the second commonest neurodegenerative cause of dementia. While there is consensus on the clinical diagnostic criteria for DLB, the use of EEG to increase the diagnostic sensitivity has not been substantiated. Material and methods ± We studied the resting EEG ®ndings in 18 consecutive patients with DLB and compared them with a control group of 20 patients with ``probable'' Alzheimer's disease (AD). We aimed to evaluate the use of EEG in a representative sample of patients with DLB. Results ± All patients with DLB ful®lled accepted clinical criteria for DLB. The DLB group had a more severe dementia than the AD group, as measured by the Mini- Mental State Examination (MMSE) test (DLB mean MMSE 9.4 and AD mean MMSE 17.2) despite a similar duration of overall severity of illness. The EEG was slow in both groups, predominantly in the 4±7 Hz range. Although there was no statistically signi®cant difference in the EEG ®ndings between the DLB and AD groups, there was a correlation between the EEG score and MMSE score (Spearman Rank correlation rs=x0.61, P<0.001). Conclusion ± These ®ndings suggest that although patients with DLB have a more aggressive course than AD, EEG abnormalities do not differ in the 2 groups. However, we believe the EEG provides important supporting diagnostic information in DLB. P. A. Barber, A. R. Varma, J. J. Lloyd, B. Haworth, J. S. Snowden, D. Neary Cerebral Function Unit, Manchester Royal In®rmary, Oxford Road, Manchester M13 9WL, United Kingdom Key words: electroencephalogram; dementia; Lewy body Dr J. S. Snowden, Cerebral Function Unit, Manchester Royal In®rmary, Oxford Road, Manchester, M13 9WL, United Kingdom Accepted for publication June 29, 1999 Alzheimer's disease (AD) and Dementia with Lewy bodies (DLB) are the two most common causes of dementia in the elderly (1, 2). A correct diagnosis of DLB has important management implications. Neuroimaging (structural and functional) has not been shown to have any convincing differential diagnostic value between these two disorders (3, 4). The EEG is commonly used as an aid in the diagnosis of DLB and AD, and there is anecdotal evidence that suggests EEG may be helpful in the diagnosis of DLB (2, 3). More information is required regarding the use of EEG as a possible adjunct to already accepted clinical criteria. We, therefore, investigated the use of EEG in a more representative sample of individuals ful®lling currently accepted clinical criteria for DLB and compared the ®ndings with a group of patients with a clinical diagnosis of AD to ascertain whether EEG can be useful in improving the diagnostic sensitivity of DLB. Materials and methods Dementia with Lewy bodies The DLB study group consisted of 18 patients drawn from a larger group of 31 consecutive referrals to the Cerebral Function Unit, Department of Neurology at Manchester Royal In®rmary diagnosed as having DLB on clinical grounds (5), between 1991 and 1996. Nine patients were excluded from the study on the grounds that there was insuf®cient EEG data. Three patients were excluded because they were considered to have Acta Neurol Scand 2000: 101: 53±56 Printed in UK. All rights reserved Copyright # Munksgaard 2000 ACTA NEUROLOGICA SCANDINAVICA ISSN 0001-6314 53