P300 IN ALZHEIMERS-DISEASE - RELATIONSHIPS TO DEMENTIA SEVERITY AND GLUCOSE-METABOLISM

In 45 patients (aged 48-85 years) with probable Alzheimer's disease (A D) according to current research criteria (NINCDS-ADRDA) with differen t stages of dementia severity (Mini Mental Status Examination (MMSE) 7 -27) the auditory evoked P300 waves were mapped and regional cerebral metabolic rates of glucose were measured by positron emission tomograp hy of 2-[F-18]fluoro-2-deoxy-D-glucose. Age adjusted P300 latency was significantly correlated to dementia severity (r= -0.33, p = 0.028), b ut no significant relationships were found for P300 amplitudes. Depend encies existed among cortical glucose metabolic rate's and MMSE with t he highest correlation coefficient for the metabolic ratio of regions typically affected and non-affected in AD (r = 0.75, p = 0.0001). A si gnificant correlation was also calculated between P300 latency and met abolic ratio (r= -0.44, p = 0.002), but no relationships were observed among P300 amplitudes and glucose metabolic rates of individual brain regions. These results indicate that P300 latency and metabolic rates but not P300 amplitudes qualify as measures of severity in AD. The la ck of regional correlations among P300 amplitudes and glucose metaboli sm is not consistent with a cortical contribution to P300 generation.