Volume 30, Supplement 1, 28–31 March 2015, Pages 225
Abstracts of the 23rd European Congress of Psychiatry
Article: 0225
A Shared Photoperiod-related Birth Seasonality Among Powerful Baseball Hitters and Lesbians with an Opposite Seasonality Among Gay Men: Maternal Melatonin May Affect Fetal Sexual Dimorphism
Mid-20 century studies of schizophrenia (SCZ) found a disease incidence excess among people born around late-February and a deficit
among those born six months later around late-August. Given that SCZ is
associated with left-handedness and may result from deficits of
cerebral asymmetries, we previously investigated hand preferences and
month of birth among professional baseball players. The results led to a
'solstitial' hypothesis implicating maternal melatonin-mediated and
other sunlight actions capable of affecting left-right brain
differentiation in the four-week-old neurulating embryo (Marzullo &
Fraser, 2005, 2009; Marzullo & Boklage, 2011). Further studies of
the same baseball players have now suggested that the same
melatonin-mediated sunlight actions could also affect testosterone
dependent male-female differentiation in the four-month-old fetus.
Independently of hand-preferences, the baseball players (n=6,829), and
particularly the stronger hitters among them, showed a unique birth
seasonality with an excess around early-November and an equally significant deficit
around early-May. In two smaller studies, American and other
northern-hemisphere born lesbians showed the same strong-hitter birth
seasonality while gay men showed the opposite seasonality.
Interestingly, the late-fourth-month fetal testosterone surge – which is
critical for sexual dimorphism—coincides with the summer-solstice in
early-November births and the winter-solstice in early-May births. A
'melatonin mechanism' is proposed based on these coincidences coupled
with evidence that in seasonal breeders maternal melatonin imparts
'photoperiodic history' to the newborn by direct inhibition of fetal
testicular testosterone synthesis. The present effects were thus
suggested to represent a vestige of this same phenomenon in man
(Marzullo, 2014: Psychiatry Res 216, 424-431).
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