Correlation of Cognitive Evoked Potentials with Memory Tests in Patients with Memory Disturbance

ABSTRACT

We performed 3 kinds of memory tests and cognitive evoked potential study, P300, in 13 patients with memory disturbance and 19 control free of neurologic symptoms or history of neurological impairment; to determine correlation of each memory test with P300 and possibility of clinical application of P300 as a quantitative test of cognitive function. Patients and control younger than 40 years of age were selected to minimize the aging effect on the cognitive function tests. Those who marked 30 points in Mini-mental state examination were chosen as control. 11 of 13 patients had brrain lesions including temporal lobe. Comparing with tests in control group, the declarative ant the procedural memory of patients were significantly impaired (p<0.05, p<0.025, respectively), and P300 latency was significantly prolonged (p<0.001). In control group, among declarative memory tests Rey-Osterreith complex figure test and enhanced cued recall had significant correlation with P300 latency (p<0.05, p<0.05, respectively), while the Tower of Toronto test which was known to evaluate precedural memory did not. In patient group there was no significant correlation between any kind of memory test and P300 latency. These results not only are consistent with previous studies which detected temporal lobe as the origin of P300 wave, but implicate that brain loci other than temporal lobe might originate P300 wave. To apply P300 as a quantitative test of cognitive function, further extensive studies using age and IQ matched control will be needed.