The Causes of Autism

Originally posted on X.

Frye, R. E., Cakir, J., McCarty, P. J., Rose, S., Delhey, L. M., Palmer, R. F., Austin, C., Curtin, P., Yitshak-Sade, M., & Arora, M. (2022). Air Pollution and Maximum Temperature Are Associated with Neurodevelopmental Regressive Events in Autism Spectrum Disorder. Journal of personalized medicine, 12(11), 1809. https://doi.org/10.3390/jpm12111809

Study Highlights

A rather complicated study, in my opinion, that cross analyzed a lot of things, ended up with miniscule effect sizes, but drew big conclusions.

1. Neurodevelopmental regression (NDR) with and without a trigger event
2. The 6 week window for the NDR
3. Seasons (e.g., summer, spring, winter)
4. PM_2.5
5. Ozone
6. Maximum temperature
7. Precipitation

Main Findings

Risk of NDR when PM_2.5 higher during weeks 3–6 of the NDR event period- 1.02x Odds Ratio

Risk of NDR when PM_2.5 higher during Weeks 5–6 of the NDR event period- 1.04x Odds Ratio

During the NDR event, there was a linear progressive increase in PM2.5 [Increase by 0.015 (SE 0.005) ug/m3/day]

Tmax was different between the children that experienced NDR as compared to those that did not

Those that experienced NDR demonstrated an average lower Tmax

Change in Tmax during the NDR event period was different for those with a history of NDR as compared to those without a history of NDR

PM_2.5, Increased Odds of NDR- 1.02x Odds Ratio

NDR with a trigger when Tmax elevated- 1.01 Odds Ratio

ASD + NDR w/o Trigger Event Season and NDR Event

Summer- 1.24x Odds Ratio
Spring- 1.09x Odds Ratio
Higher PM2.5- 1.04x Odds Ratio

ASD + NDR w/ Trigger Event Season and NDR Event

Summer- 1.19x Odds Ratio
Spring- 1.26x Odds Ratio
Tmax- 1.01x Odds Ratio

5 Interesting Quotes

1. NDR is often associated factors such as seizure and/or fever.

2. NDR is also reported in individuals with mitochondrial disease with an infection preceding by 7–10 days and when ASD develops, with a fever preceding within a similar time period.

3. Many families do not report any obvious associated factors or ‘triggers’ when a NDR event occurs.

4. This study was not able to provide a temporal link between air pollution and the NDR event, but rather found that the peak in air pollution occurred coincident with the NDR event.

5. It appears that those children who experienced the NDR event did have higher exposure to PM_2.5 during the year before and after the NDR event, suggesting that their physiological systems may have been under greater chronic stress in general while the event occurred.