Is the P300 wave an endophenotype for schizophrenia? A meta-analysis and a family study.
BACKGROUND
We assessed the usefulness of the P300 wave as endophenotype for schizophrenia by means of a meta-analysis of the literature as well as our own family study.


METHODS
Meta-analysis: We conducted a systematic search for articles published between 1983 and 2003 that reported P300 measures in non-psychotic relatives of schizophrenic patients and in healthy controls. Meta-regression analyses were performed using a random effects procedure. The pooled standardized effect size (PSES) was calculated as the difference between the means of the two groups divided by the common standard deviation. Local study: We examined the P300 wave with a standard two-tone oddball paradigm in 30 patients with schizophrenia, 40 non-psychotic relatives, and 40 controls using linear mixed models.


RESULTS
Meta-analysis: We pooled 472 relatives and 513 controls. The P300 amplitude was significantly reduced in relatives (PSES = 0.61; 95% CI: 0.30 to 0.91; P < 0.001). The P300 latency was significantly delayed in relatives (PSES of -0.50; 95% CI: -0.88 to -0.13; P = 0.009]. Local study: The patients showed a trend for amplitude reductions (P = 0.06) and significant latency delays (P < 0.01). The relatives displayed normal amplitude but had significant latency delays (P = 0.01). The P300 amplitude and especially the P300 latency are promising alternative phenotypes for genetic research into schizophrenia.
Bramon
Elvira
E
Institute of Psychiatry, P.O. box 63, De Crespigny Park, London SE5 8AF, UK. e.bramon@iop.kcl.ac.uk
McDonald
Colm
C
Croft
Rodney J
RJ
Landau
Sabine
S
Filbey
Francesca
F
Gruzelier
John H
JH
Sham
Pak C
PC
Frangou
Sophia
S
Murray
Robin M
RM
D000293:Adolescent; D000328:Adult; D000368:Aged; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D005190:Family; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D012559:Schizophrenia / Q000235:genetics* / Q000503:physiopathology*