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Men with a common autism-linked variant of CD38, a gene that regulates levels of the ‘trust hormone’ oxytocin, benefit more from the hormone than do those with other variants, according to a study published in the May issue of Neuropsychopharmacology1.
In the new study, researchers used functional magnetic resonance imaging (fMRI) to scan the brains of 55 neurotypical men. Of the 55, 30 carry the CC CD38 gene variant, 23 have the CA variant and 2 have AA.
The participants looked at a series of photos and were asked to identify the image that matched another ‘target’ picture. The photos were either social images that were positive (happy faces, or couples sharing intimate moments) or negative (angry faces, or someone physically threatening another person), or non-social control images (geometric shapes).
The participants performed the same test twice in one day, once after taking oxytocin and once after taking placebo, both via nasal spray. Neither the participants nor the researchers knew which compound the participants had taken.
Overall, men with the CC variant are slower to respond when looking at images of social scenes than those with the AA or AC variants, the study found. They also showed improvement in their reaction time after taking oxytocin, whereas men in either of the other two groups did not, the study found.
Men with the CC variant may produce less oxytocin, resulting in an increase in the number of oxytocin receptors and, in turn, making them more sensitive to inhaled oxytocin, the researchers say.
The fusiform gyrus is more active during the social tests than during the non-social tests in men with the CC variant, but not in those with either A variant, the study found. This effect is more pronounced after oxytocin treatment than after placebo.
The results remained the same with both positive and negative photos, suggesting that oxytocin may affect overall attention to social information, the researchers say.
The results show that oxytocin treatment could benefit individuals who produce less of the hormone. This is consistent with results from a 2010 study showing that only neurotypical men who have some traits of autism, based on the Autism Spectrum Quotient test, show improvements in empathy after taking oxytocin.
1: Sauer C. et al. Neuropsychopharmacology 37, 1474-1482 (2012) PubMed
2: Munesue T. et al. Neurosci. Res. 67, 181-191 (2010) PubMed