Despite a lot of research on how and why autism and other neurodevelopmental disorders occur, the underlying causes remain unidentified. Although studies established a link between allergies and attention deficit hyperactivity disorder (ADHD) and autism; and inflammation and the risk of schizophrenia, ADHD, and autism, the cellular mechanisms behind these phenomena are not understood. The current study focuses maternal allergies.
Autism is more common in males than females; Lenz and colleagues investigated this gender difference in rats.
The study team sensitized female rats to ovalbumin prior to their pregnancy and then 15 days into the pregnancy the rats’ immune system was triggered with an allergen. Once sensitized, the team studied how immune reactions in mother made brought about changes in pups. Initially, the number and types of immune cells in the rat’s developing brains were measured. Then, their behavioral patterns such as learning ability, anxiety-like behavior and their overall activity levels were measured. Finally, the team measured the density of dendritic spines in the pup’s brains- points of synaptic connection between nerve cells in the rat’s frontal cortex to assess their cognitive condition and maturity level.
It was observed that the pups of those rats whose immune system had been sensitized with an allergen had a higher number of mast cells in brain. They also showed a decrease in another type of immune cell – microglia and shown less anxiety-like behavior. The findings were same in both sexes.
The current study was led by Kathryn Lenz and presented at Neuroscience 2016. Kathryn said “Young rats engage in social play and males are rougher and tumble and usually play much more than females.” However, the males in the allergy group were found to roughhouse with their peers significantly less. “The males born to the allergen exposed mothers looked more like females. They were more socially reserved. They were really hyperactive but socially disengaged. That looks a bit like ADHD.”
In addition to this, a lot of variations were observed with respect to the mental flexibility of the rats; pups born to allergen exposed mothers struggled much more when challenged.
Both male and female rats in the allergen group struggled to adapt to the differing trials. However, the male rats in the allergen group were identified to struggle more than the females.
Kathryn comments, “We are truly fascinated in determining out unidentified factors in psychological problems and in variations between male and female brain development as it associates to autism, ADHD, and other problems.”
“This is proof that prenatal exposure to allergens modifies brain development and function and that could be an underappreciated aspect in the development of neuro-developmental disorders.”