Modality-specific changes in P300 parameters in patients with dementia of the Alzheimer type.

BACKGROUND

The relationship between the parameters of the P300 potential and the degree or profile of cognitive decline remains controversial. The aim of our study was to evaluate parameters of auditory and visual P300 in patients with mild and moderate dementia of the Alzheimer type (DAT) and to correlate these with neuropsychological test results.

MATERIAL/METHODS: The study group comprised 13 patients with DAT and 13 healthy, age-matched controls. Auditory and visual event-related potentials were evoked using a basic oddball paradigm. P300 latency and amplitude were compared in patients with DAT and controls and between subgroups of patients with mild and moderate DAT. Correlations between P300 parameters and the results of the Mini-Mental State Examination (MMSE), the Global Deterioration Score (GDS), and the Alzheimer's Disease Assessment Scale (ADAS-cog) were also analyzed.

RESULTS

The mean latency of auditory P300 was significantly prolonged, and the mean amplitude of visual P300 was significantly lower in the DAT patients. 4 patients with DAT (31%) had a prolonged latency of auditory P300. No significant differences in P300 parameters were found between mildly demented and controls or between mildly and moderately demented. A positive correlation was found between MMSE score and auditory P300 latency in Fz and visual P300 amplitude in Cz.

CONCLUSIONS

P300 parameters undergo significant, modality-specific changes in patients with DAT. However, they are not sensitive enough to differentiate early dementia from normal aging.