There is evidence that fathering a child as an older man, increases the child’s risk of autism. The assumption has been that, as a man ages, there is a greater risk of mutation to the genes carried by the sperm cells.
However, here is an interesting alternative explanation:
Gratten and his colleagues developed a fifth model to test an alternate explanation for the paternal age effect: that men with a high genetic risk for autism — and who show autism traits — tend not to have children until they are older.
“We don’t think that this alternative mechanism, which is really just a hypothesis, accounts for all the risk on its own,” Gratten says. “Probably de novomutations contribute, and this mechanism may also contribute, and many others may as well.”
Still, this alternative hypothesis “makes sense for autism and seems quite likely for schizophrenia too,” says Bernie Devlin, professor of psychiatry at the University of Pittsburgh, who was not involved in the work. That’s because de novo mutations are believed to contribute to only a small fraction of risk for either condition. For autism, de novo mutations are thought to account for about 3 percent of risk.
Uta Frith is one of the giants of developmental psychology, here, as part of a series presented by Nature, she describes her Ph.D. thesis on autism:
I think all the videos in this series are interesting, so many of the scholars have some ambivalence about their dissertations; looking back at their work as novice scholars from the vantage point of expertise.
I was hesitant to blog about this case report in the journal Pediatrics. I decided that it was better for me to write about it and emphasize the limitations, since it seems likely that supplement manufactures and some media will make exaggerated claims. The report:
“Autism spectrum disorder (ASD) is a common neurodevelopmental disorder caused by a complex interaction between genetic and environmental risk factors. Among the environmental factors, vitamin D3 (cholecaliferol) seems to play a significant role in the etiology of ASD because this vitamin is important for brain development. Lower concentrations of vitamin D3 may lead to increased brain size, altered brain shape, and enlarged ventricles, which have been observed in patients with ASD. Vitamin D3 is converted into 25-hydroxyvitamin D3 in the liver. Higher serum concentrations of this steroid may reduce the risk of autism. Importantly, children with ASD are at an increased risk of vitamin D deficiency, possibly due to environmental factors. It has also been suggested that vitamin D3 deficiency may cause ASD symptoms. Here, we report on a 32-month-old boy with ASD and vitamin D3 deficiency. His core symptoms of autism improved significantly after vitamin D3 supplementation. This case suggests that vitamin D3 may play an important role in the etiology of ASD, stressing the importance of clinical assessment of vitamin D3 deficiency and the need for vitamin D3 supplementation in case of deficiency.”
The most important thing to note is that this is a case study, an observation of a single individual. We cannot know if the ASD symptoms would have lessened without vitamin D supplementation. Also, there is certain amount of subjectivity in evaluating ASD symptoms. At best this study is suggestive of an important avenue of research. The claim that vitamin D deficiency is a cause of autism is plausible, but we need randomized double blind research to have confidence in this claim.
A paper, published in The Journal of Autism and Developmental Disorders, suggests that autism may be associated with a unique pattern of brainwave activity.
Here is the abstract:
“Atypical processing and integration of sensory inputs are hypothesized to play a role in unusual sensory reactions and social-cognitive deficits in autism spectrum disorder (ASD). Reports on the relationship between objective metrics of sensory processing and clinical symptoms, however, are surprisingly sparse. Here we examined the relationship between neurophysiological assays of sensory processing and (1) autism severity and (2) sensory sensitivities, in individuals with ASD aged 6–17. Multiple linear regression indicated significant associations between neural markers of auditory processing and multisensory integration, and autism severity. No such relationships were apparent for clinical measures of visual/auditory sensitivities. These data support that aberrant early sensory processing contributes to autism symptoms, and reveal the potential of electrophysiology to objectively subtype autism.”
And here is the press release giving a summary of the findings.
Finally, here is a video overview: