Abnormal P300 in people with high risk of developing psychosis.
BACKGROUND
Individuals with an "at-risk mental state" (or "prodromal" symptoms) have a 20-40% chance of developing psychosis; however it is difficult to predict which of them will become ill on the basis of their clinical symptoms alone. We examined whether neurophysiological markers could help to identify those who are particularly vulnerable.


METHODS
35 cases meeting PACE criteria for the at-risk mental state (ARMS) and 57 controls performed an auditory oddball task whilst their electroencephalogram was recorded. The latency and amplitude of the P300 and N100 waves were compared between groups using linear regression.


RESULTS
The P300 amplitude was significantly reduced in the ARMS group [8.6+/-6.4 microvolt] compared to controls [12.7+/-5.8 microvolt] (p<0.01). There were no group differences in P300 latency or in the amplitude and latency of the N100. Of the at-risk subjects that were followed up, seven (21%) developed psychosis.


CONCLUSIONS
Reduction in the amplitude of the P300 is associated with an increased vulnerability to psychosis. Neurophysiological and other biological markers may be of use to predict clinical outcomes in populations at high risk.
Bramon
Elvira
E
Institute of Psychiatry, Division of Psychological Medicine-Box 63, De Crespigny Park, London, SE5 8AF, UK. elvira.bramon@iop.kcl.ac.uk
Shaikh
Madiha
M
Broome
Matthew
M
Lappin
Julia
J
Bergé
Daniel
D
Day
Fern
F
Woolley
James
J
Tabraham
Paul
P
Madre
Mercè
M
Johns
Louise
L
Howes
Oliver
O
Valmaggia
Lucia
L
Pérez
Víctor
V
Sham
Pak
P
Murray
Robin M
RM
McGuire
Philip
P
D000293:Adolescent; D001921:Brain / Q000503:physiopathology*; D004569:Electroencephalography; D018913:Event-Related Potentials, P300; D005072:Evoked Potentials, Auditory; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D011618:Psychotic Disorders / Q000503:physiopathology*; D012307:Risk Factors