Decreased neurotrophic response to birth hypoxia in the etiology of schizophrenia.
BACKGROUND
Obstetric complications, particularly fetal hypoxia, are associated with increased risk for schizophrenia later in life. Such factors are also related to increased severity of certain neuropathological features of schizophrenia, including hippocampal and cortical gray matter reduction, among individuals with a genetic susceptibility to the disorder. However, the molecular mechanisms underlying these associations are unknown. Here, we sought to determine whether neurotrophic factors, which are stimulated as part of a neuroprotective response to fetal distress, are differentially expressed in cord blood samples at the time of birth following fetal hypoxia, maternal hypertension/small for gestational age status, and/or prematurity among individuals who developed schizophrenia as adults, as compared with control subjects.


METHODS
One hundred eleven cases with psychotic disorders (70 with schizophrenia) and 333 control subjects matched for gender, race, and date of birth were drawn from the Philadelphia cohort of the National Collaborative Perinatal Project in a nested case-control study. Brain-derived neurotrophic factor (BDNF) was assayed from cord and maternal blood samples taken at delivery and stored at -20 degrees C for 45 to 50 years.


RESULTS
Among control subjects, birth hypoxia was associated with a significant (10%) increase in BDNF in cord samples, while among cases, hypoxia was associated with a significant (20%) decrease in BDNF. This differential response to fetal hypoxia was specific to schizophrenia and was not explained by other obstetric complications or by the BDNF valine (val) to methionine (met) polymorphism at codon 66 (val66met).


CONCLUSIONS
These findings provide serologically based prospective evidence of disrupted neurotrophic signaling in response to birth hypoxia in the molecular pathogenesis of schizophrenia.
Cannon
Tyrone D
TD
Department of Psychology, University of California Los Angeles, Los Angeles, California 90095-1563, USA. cannon@psych.ucla.edu
Yolken
Robert
R
Buka
Stephen
S
Torrey
E Fuller
EF
D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics* / Q000378:metabolism*; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D005311:Fetal Hypoxia / Q000150:complications*; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D008297:Male; D008715:Methionine / Q000235:genetics; D008875:Middle Aged; D012307:Risk Factors; D012559:Schizophrenia / Q000209:etiology* / Q000378:metabolism* / Q000473:pathology; D014633:Valine / Q000235:genetics
D019208:Brain-Derived Neurotrophic Factor; D008715:Methionine; D014633:Valine