Conception season and cerebral asymmetries among American baseball players: implications for the seasonal birth effect in schizophrenia.
People with schizophrenia and children born with neural tube defects both tend to be conceived most often in May-June, about a month before the summer solstice, and least often in November-December, a month before the winter solstice. Such timings, coupled with evidence of cerebral asymmetry deficits in schizophrenia, and evidence that asymmetry development and neural tube closure represent concurrent fourth-embryonic-week processes both sensitive to oxidant stress, led us to the hypothesis that pro-oxidant sunlight actions capable of affecting the mother's blood could result in a peri-June peak of inhibition and a peri-December peak of facilitation of both processes. Here, using birth and hand preference data from baseball statistics, we tested the hypothesis's prediction that, as a group representing minimal cerebral lateralization, left-handed players would show the same conception rhythm as that observed in the above disorders. We found that not only strict left-handers (those both batting and throwing left) were most often conceived in May-June but that also strict right-handers and other players denoting more extreme levels of cerebral lateralization were most often conceived in November-December.
Marzullo
Giovanni
G
Per Aspera Research Foundation, New York, NY 10023, United States. gmarzullo@prspr.org
Fraser
Frank Clarke
FC
D001484:Baseball / Q000502:physiology* / Q000706:statistics & numerical data; D001719:Birth Certificates; D001921:Brain / Q000503:physiopathology*; D015331:Cohort Studies; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D012559:Schizophrenia / Q000503:physiopathology*; D012621:Seasons; D014481:United States