Could Aging Fathers Explain the Rise in Autism?
Autism is a subject near and dear to my heart, and April is Autism Awareness Month. So this week I’ll focus on some disturbing new information about autism. By now, most of us are aware that autism is a growing concern in America. This is not hyperbole. To put the situation in perspective, consider this simple statistic: between 1991 and 1997, there was a breathtaking 556-percent increase in the prevalence of autism diagnoses. Some of this can be chalked up to greater awareness and better diagnosis. But better diagnosis surely cannot account entirely for the astronomical rise in cases.
Characterized by problems with communication and social interaction, and often accompanied by repetitive and restrictive behaviors, autism is related to alterations in the brain’s information-processing capabilities. Autism falls on a spectrum (autism spectrum), which includes higher-functioning people (Asperger syndrome) and a condition called pervasive developmental disorder, not otherwise specified (PDD-NOS).
It’s long been thought that genetic factors play a role, although the exact nature of these influences was unclear. There’s also some controversy about the potential role of the environment, including possible effects from pollutants like heavy metals, pesticides and other toxins. I personally believe it’s extremely important to eliminate potential sources of toxins from the environment, especially when it comes to infants’ growing nervous systems. I also believe a healthful diet is crucial for good neurological development.
But new evidence suggests prospective parents may want to rethink a relatively recent social trend: delayed fatherhood. According to articles that appeared recently in the influential journal Nature, the biggest culprit may be mutations in the sperm of aging fathers. These mutations reflect a sort of copying error. The father’s genes are not the problem; faulty copies are.
Most of us realize that a woman’s biological clock enters the reproductive red zone at about 35 years of age. It’s always been assumed, though, that men can successfully father children well into their golden years. Now, it appears that things are not so simple. Tomorrow I’ll delve deeper into this fascinating emerging story.
Happé F, Ronald A. The 'fractionable autism triad': a review of evidence from behavioural, genetic, cognitive and neural research. The 'fractionable autism triad': a review of evidence from behavioural, genetic, cognitive and neural research. Neuropsychol Rev. 2008 Dec;18(4):287-304. doi: 10.1007/s11065-008-9076-8. Epub 2008 Oct 28.
Neale BM, Kou Y, Liu L, Ma'ayan A, Samocha KE, Sabo A, et al. Patterns and rates of exonic de novo mutations in autism spectrum disorders. Nature. 2012 Apr 4;485(7397):242-5. doi: 10.1038/nature11011.
O'Roak BJ, Vives L, Girirajan S, Karakoc E, Krumm N, Coe BP, et al. Sporadic autism exomes reveal a highly interconnected protein network of de novo mutations. Nature. 2012 Apr 4;485(7397):246-50. doi: 10.1038/nature10989.