Bimodal rhythms of general conceptions and the birth-month phenomenon in schizophrenia, neural tube defects, and laterality: A solstitial hypothesis

✍ Scribed by Giovanni Marzullo; Charles E. Boklage

• Publisher: John Wiley and Sons
• Year: 2011
• Tongue: English
• Weight: 631 KB
• Volume: 91
• Category: Article
• ISSN: 1542-0752
• DOI: 10.1002/bdra.20806

✦ Synopsis

BACKGROUND: Studies of early to mid-20th century birth records found that people with schizophrenia had been born most often in late winter (February-March) and least often in late summer (August-September). A late-winter birth peak coinciding with the schizophrenia peak also occurred during those times in the non-schizophrenic general populations. O ¨dega ˚rd suggested in 1977 that the schizophrenia and general-birth rhythms represented the same phenomenon, with the former being a mere exaggeration of the latter. However, unlike the schizophrenia rhythm, the general-population birth rhythm was bimodal, with a second peak occurring in August-September and coinciding with the schizophrenia dip. METHODS: We reexamined those intriguing coincidences in light of newer findings including evidence of a schizophrenia-like rhythm of births in neural tube defects (NTDs) and extreme left-handedness. RESULTS: Based on U.S. data, we found that for all three anomalies (schizophrenia, NTDs, and sinistrality) the maximum risk and the minimum risk (a resistance peak) coincided with, respectively, the February-March and August-September peaks of general-population births. We also found that, while superficially similar, the two general-birth peaks were more likely to represent different phenomena with opposite causes (possibly the June vs December sunlight) and radically different mechanisms of enhanced embryonic survival (increased post-implantation viability in the February-March case and increased implantation rates in the August-September case). CONCLUSIONS:

We propose a mechanism of selective embryonic survival whereby the birth-month-associated risk levels for the various anomalies would all represent traits genetically or epigenetically inherent to the two differently selected populations of surviving embryos. Birth Defects Research (Part A) 91: 249-257, 2011.