Clinical study on the subcomponents of P300 event-related potential in patients with vascular cognitive impairment

Objective To investigate the characteristics of P3a and P3b which are the subcomponents of P300 event-related potential in patients with vascular cognitive impairment (VCI) ,and to investigate the relations between P3a,P3b and the changes of cognitive function and cerebral blood flow. Methods Thirty patients with VCI and twenty two normal subjects were tested for P3a and P3b cognitive function ischemic focus and cerebral blood flow and then analyzed for correlation. Results (1) The latency of P3a ((446 ± 71) ms, (429 ± 67) ms, (446±61)ms,(428±66)ms)and P3b((496 ±73)ms,(478 ±75)ms,(498 ±77)ms,(483 ±77)ms) was significantly prolonged in patients with VCI compared with that in normal subjects in all recorded regions(P<0.01) . The amplitude of P3a in patients with VCI ((3.3 ±2.6)μV,(3.3 ± 1.8)μV) was significantly lower than that in normal subjects in Fz and Pz (P<0.01) ,and the amplitude of P3b in patients with VCI((4.5 ±2.5)μV,(6.4 ± 3.8)μV,(5.3 ±3.8)μV,(5. 3 ±3.0)μV) was significantly lower than that in normal subjects in all recorded regions (P < 0.01 or P<0.05) . (2) The latency of P3a and P3b in patients with VCI was negatively related to the scores of sub items of attention and MMSE total scores (P < 0.05 or P < 0.01), the amplitude of P3a was positively related to the scores of MMSE total scores(P<0.05) ,the amplitude of P3b was positively related to the scores of attention and MMSE total scores(P<0.05). (3) The latency of P3a in patients with VCI was positively related to frontal lobe(P<0.05) ,and the latency of P3b was positively related to parietal lobe(P<0.05). (4) The latency of P3a in patients with VCI was positively related to RILMCA,RILACA and RIRACA(P<0.05 orP<0.01) ,the latency of P3b was positively related to RILMCA,RIRMCA and RIRACA(P<0.05 orP<0.01) ,and the amplitude of P3a was positively related to RILACA(P<0.01). Conclusion P3a and P3b are good objective indexes for testing the descent of cognitive function in patients with VCI,which can provide reference basis for the clinical diagnosis. Key words: Vascular cognitive impairment; Event related potential; Mini mental state examination