Breast Milk for 1 Year for Fragile X Infants May Reduce Autism Risk

Infants with fragile X syndrome who are fed with breast milk for a minimum of one year have a decreased prevalence of autism, a retrospective study found.

However, breast milk consumption was linked to the earlier development of gastrointestinal problems and allergies among these infants, according to the investigator.

Overall, the findings support the neuroprotective benefits associated with breastfeeding.

“There was a 1.7-fold reduction in the prevalence of autism in [fragile X] participants who were fed breast milk for 12 months or longer,” Cara J. Westmark, PhD, of the University of Wisconsin, the study investigator found.

The study, “Consumption of Breast Milk Is Associated with Decreased Prevalence of Autism in Fragile X Syndrome,” was published in the journal Nutrients.

Breast milk is the ideal nutrition regimen for at least the first six months of life, according to the American Academy of Pediatrics. It is linked with several health benefits, including a lower incidence of both autism spectrum disorder (ASD) and attention-deficit/hyperactivity (ADHS) disorder, a lesser likelihood of obesity, and even fewer infections.

In a previous study with 226,000 children, researchers observed that breastfeeding was associated with a significantly reduced risk of obesity. Moreover, the risk correlated with the duration of time that the babies were breastfed.

Although there is strong evidence that breast milk has benefits for the health of developing infants, whether it has an impact on the risk for neurodevelopmental disabilities, such as fragile X, is largely unknown.

A preclinical study with a mouse model of fragile X showed that diet had a significant impact on seizure severity. In particular, a soy-based diet increased the number of seizures triggered by a loud sound — called audiogenic induced seizures. Soy-based diets in children with autism also have been linked to an increased frequency of seizures and epilepsy, and worsened disease severity.

These findings suggest that, while consumption of soy-based infant formula could lead to more severe disease manifestations and more symptoms in fragile X, breastfeeding could have a protective effect.

To test this hypothesis, Westmark, from the university’s department of neurology, conducted a retrospective analysis using data from families enrolled in the Fragile X Online Registry with Accessible Database, known as FORWARD. It contains in-depth information about individuals with fragile X, including data on nutrition habits and the frequency and duration of breastfeeding.

In total, Westmark analyzed data from 199 individuals with fragile X, mostly boys (73%), who had an average age of 18 and were Caucasian.

Out of 194 patients (97%) whose caregivers replied to the FORWARD Nutrition survey, 142 of them (73%) reportedly were breastfed during their first year of life. These findings are in agreement with the estimates by the Centers for Disease Control, from 2010 to 2017, among the U.S. population. Those estimates range from 77% to 84%.

Among breastfeeding respondents (141 out of 142), 29% were exclusively fed with breast milk for a period ranging from two month to up to 2.5 years (30 months).

There were no statistically significant differences in the prevalence of autism, food allergies, diabetes, gastrointestinal problems, seizures, or allergies between those being fed any breast milk during the first year of life and those who were never breastfed.

However, taking into account the length of time infants with fragile X were breastfed — at least three, six, or 12 months (one year) — resulted in a statistically significant decrease of 1.7 fold in autism prevalence. Specifically, the prevalence dropped from 53% to 32%. Among those fed exclusively with breast milk, this decrease was 1.9 fold.

The analysis revealed a positive correlation between breastfeeding duration and the prevalence of no additional diseases (comorbidities). That means that the longer the infant was breastfed, the less likely he or she was to have additional medical conditions, to include autism and seizures.

Infants with caregiver-reported autism were two-fold less likely to be breastfed by the age of 1.

No significant differences were found between breastfeeding and seizure prevalence, although a trend for a reduction in seizures was seen with longer breastfeeding periods of 12 months or more.

Although an increased length of breastfeeding time seemed to confer some degree of protection against gastrointestinal problems and allergies, it nevertheless associated with these problems developing earlier in life, beginning within the child’s first three years. Those fed breast milk exclusively had gastrointestinal problems arising even earlier, at a mean age of 16 months (less than 1.5 years).

“These data suggest that while long-term and exclusive use of breast milk are protective against autism, breast milk is associated with the earlier development of GI [gastrointestinal] problems in participants with FXS [fragile X],” Westmark wrote.

A similar effect was observed for allergies. On average, breastfed children with fragile X began developing allergies more than three years (38 months) earlier.

The most common reasons for stopping breastfeeding included not enough milk production by the mother and the infant’s age, followed by the need to wean the child due to mother-related health concerns or work-related issues, among others.

“Health benefits associated with breast milk could be conferred through the higher bioavailability of nutrients, an altered gut microbiome, greater immunity from maternal antibodies, increased mother/child bonding, and/or better pre- and post-natal healthcare,” Westmark wrote.

Such benefits, the researcher hypothesized, also could be linked to the insulin-like growth factor 1 (IGF-1) levels found in breast milk. Children with autism have been reported to have lower levels of IGF-1, which leads to loss of myelin, the protective coat surrounding nerve cells, and in turn can result in the development of autism.

The study’s limitations included the absence of longitudinal studies, which are not possible in this population due to a later age at diagnosis, and possible recall and reporting biases.