Maternal Childhood Experience, Mate Choice, And Autism

Here is an interesting paper from several years ago, abstract:

Maternal experience of childhood abuse has been associated with offspring autism. To explore whether familial tendency towards autistic traits-presumably related to genetic predisposition-accounts for this association, we examined whether women who experienced childhood abuse were more likely to select mates with high levels of autistic traits, and whether parental autistic traits accounted for the association of maternal abuse and offspring autism in 209 autism cases and 833 controls. Maternal childhood abuse was strongly associated with high paternal autistic traits (severe abuse, OR = 3.98, 95% CI = 1.26, 8.31). Maternal and paternal autistic traits accounted for 21% of the association between maternal abuse and offspring autism. These results provide evidence that childhood abuse affects mate selection, with implications for offspring health.

In summary, the link between a history of childhood abuse of woman and rates of offspring autism may in part be due to the fact that such women tend to pick as mates men with higher levels of autistic traits.  This is based on the probability of an association between autistic traits in parents and children. So, the fact that the fathers have more autistic traits is one reason why the children may have such traits.  In other words, 21% of the association between mother's childhood abuse and offspring autism is due to the fact that the mothers pick as mates men who have more autistic traits tat are passed on to the children.

Elimination Diets For Neurodevelopmental Disorders.

Elimination diets attempt to identity foods that cause certain symptoms or disorders.  Here is a paper that focuses on elimination diets as interventions for, e.g., attention deficit hyperactivity disorder and autism spectrum disorder.  Abstract:

Nutrition plays an important role in neurodevelopment. This insight has led to increasing research into the efficacy of nutrition-related interventions for treating neurodevelopmental disorders. This review discusses an elimination diet as a treatment for attention deficit hyperactivity disorder and autism spectrum disorder, with a focus on the efficacy of the food additives exclusion diet, gluten-free/casein-free diet and oligoantigenic diet. Furthermore, we discuss the potential mechanisms of elimination diets' effects in these neurodevelopmental disorders. The main candidate mechanism is the microbiome-gut-brain axis possibly involving complex interactions between multiple systems, including the metabolic, immune, endocrine, and neural system. We conclude with practical implications and future directions into the investigation of an elimination diet's efficacy in the treatment of attention deficit hyperactivity disorder and autism spectrum disorder.

Once again we see the power of nutrition and diet to affect serious human health and developmental problems, and we note the mention of "the microbiome-gut-brain axis" - demonstrating, also once again, the relevance of the gut microbiome to various aspects of human well-being.

Does Maternal Gut Microbiota Affect Autism Risk?

This paper linked here shows that certain gut microbiota can trigger inflammatory responses in female mice that increases the chances of offspring with abnormalities associated with maternal immune activation; in humans, such abnormalities include autism.  Thus, if these findings also apply to humans, a possible link between the gut microbiota of the mother and risk of autism in the child.  Abstract:

Maternal immune activation (MIA) contributes to behavioural abnormalities associated with neurodevelopmental disorders in both primate and rodent offspring. In humans, epidemiological studies suggest that exposure of fetuses to maternal inflammation increases the likelihood of developing autism spectrum disorder. In pregnant mice, interleukin-17a (IL-17a) produced by T helper 17 (TH17) cells (CD4+ T helper effector cells involved in multiple inflammatory conditions) induces behavioural and cortical abnormalities in the offspring exposed to MIA. However, it is unclear whether other maternal factors are required to promote MIA-associated phenotypes. Moreover, the underlying mechanisms by which MIA leads to T cell activation with increased IL-17a in the maternal circulation are not well understood. Here we show that MIA phenotypes in offspring require maternal intestinal bacteria that promote TH17 cell differentiation. Pregnant mice that had been colonized with mouse commensal segmented filamentous bacteria or human commensal bacteria that induce intestinal TH17 cells were more likely to produce offspring with MIA-associated abnormalities. We also show that small intestine dendritic cells from pregnant, but not from non-pregnant, females secrete IL-1β, IL-23 and IL-6 and stimulate T cells to produce IL-17a upon exposure to MIA. Overall, our data suggest that defined gut commensal bacteria with a propensity to induce TH17 cells may increase the risk of neurodevelopmental disorders in the offspring of pregnant mothers undergoing immune system activation owing to infections or autoinflammatory syndromes.

Autism and maternal infections during pregnancy

There is epidemiological evidence that viral infections during pregnancy associate with higher frequency of autism in children. Recently, experimental data on this association were published in Science.

The phenomenon underlying the correlation is known as maternal immune activation. In experimental models (mice), the maternal immune activation increases the levels of a molecule, interleukin-17a, which affects the fetal brain development. Based upon these results, the authors of the study have proposed that targeting cells involved in the maternal immune response (i.e., the T helper 17 cells) may reduce the risk of having children with inflammation-associated autism.

Two years ago, another publication associated maternal infections during pregnancy not only with autism, but also with schizophrenia. In addition, the authors discussed clinical data that infections in pregnancy may increase the risk of epilepsy, cerebral palsy, Alzheimer and Parkinson diseases in the offspring.

What does this mean for pregnant women? Does it mean that it is better for future moms to not work, and limit their exposure to environments/settings where they can easily contract infectious diseases? This discussion is still missing from the publications. Another unanswered question is whether the increased rates of autism in the past years is due to the increased employment of women (see statistics in the graph below)

By Rcragun (Own work) [CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons

Many likely causes for the increased rates of autism have been discussed, such as the increased awareness of the condition (and therefore, its more frequent diagnosis), television, chemicals, vaccines, older age of the parents.  However, we need to consider additional factors, including the phenomenon of maternal immune activation and its effects on the fetal development of the central nervous system.
 
There are several historic phases, during which women have increased their representation in the workforce, and the fourth phase (from the late 70s to present days) coincides with the increased rates of diagnosed autism.  

Association/correlation does not mean causation; however, it might be prudent to protect pregnant women by offering  better work conditions – shorter workdays, days working from home, and a longer paid maternity leave that starts months before the due date.