USE OF ELECTROENCEPHALOGRAPHY TO DETECT ALZHEIMERS-DISEASE IN DOWNS-SYNDROME

We studied the role of electroencephalography (EEG) in the diagnosis o f Alzheimer-type dementia in patients with Down's syndrome. 197 patien ts with Down's syndrome were monitored for 5 to 8 years. Aspects of co gnitive functioning were assessed twice yearly. EEGs were scored in a blind fashion, and changes in the EEG were compared to changes in cogn itive functioning. When possible, a neuropathological post-mortem exam ination was performed. Cognitive functioning was drastically reduced i n 29 patients. The dominant occipital rhythm became slower at the onse t of the cognitive deterioration, and eventually disappeared. In 11 of these patients neuropathological examination showed a severe form of Alzheimer's disease. Changes in the frequency of the dominant occipita l rhythm could distinguish between Alzheimer's disease or other causes as underlying the cognitive decline. Slowing of the dominant occipita l rhythm seems to be related to Alzheimer's disease in patients with D own's syndrome, and the frequency of the dominant occipital activity d ecreases at the onset of cognitive deterioration. The EEG is thus an i mportant tool in the clinical diagnosis of Alzheimer-type dementia in patients with Down's syndrome.