SUNY Plattsburgh at Queensberry
Autism is a neurological disorder known to affect several brain regions. Studies have shown that the gut- brain communicate and have effects on GI issues and behaviors associated with ASD (Marler, Ferguson, Lee, Peters, Williams, McDonnell, Veenstra-Vanderweele, 2017). Recent studies have shown that changes in gut microbiota can have effects on GI and produce problem behaviors (Vulong& Hsiao, 2017). Gastrointestinal dysfunction has been correlated with the degree of social impairment in ASD (Israelyan, & Margolis, 2018). Gastrointestinal and problem behavioral issues have diminished in mice through the use of probiotics (Bruce-Keller, Salbaum, & Berthoud, 2018). This is an exploratory study with a multifactorial design which will look at the effects of diet on children with ASD and sibling pair, within and between groups on decreasing gastrointestinal (GI) and problem behaviors. By increasing the diversity of the microbiota in children at a young age, behavioral and GI could improve.
The brain-gut-microbiota axis (BGM) has many proposed methods of communication. The central nervous system (CNS) through bidirectional communication of the vagus nerve, sends afferent and efferent messages between the gut and the brain (Dinan, Stilling, Stanton, & Cryan, 2015). The neuroendocrine and neuro-immune systems, immune cells through the production of cytokines and the HPA axis and the production of short chain fatty acids (SCFAs) (Dinan et al., 2015). SCFAs butyrate, acetate, and propionate produced in the gut have neuroactive properties. By entering the blood and accessing brain regions through free fatty acid receptor 2 (FFA2) and FFA3. (Dinan, et al., 2015). The immune system has bidirectional bacterial effects on the CNS causing fluctuating levels of pro- and anti-inflammatory cytokines in the hypothalamus, expressing a ‘potent release of corticotrophin-releasing hormone (CRH) which is the dominant peptide regulator for the hypothalamic-pituitary-adrenal axis (HPA)’ (Dinan et al., 2015). Communication happens through neurotransmitters GABA, norepinephrine, dopamine, and serotonin as well as tryptophan metabolism (Dinan, et al., 2015).
The microbiome is a complex ecosystem that can effect behaviors, brain development, and function through endocrine, immune, and neural pathways (Wyatt, 2017). Prevotella, Ruminococcus, and Bacteroides make up the three different enterotypes of the microbiome and are found in all sexes, ages, nationalities, and body mass indexes. (Dinan, et al., 2015). Healthy microbiomes contain 85% beneficial bacteria and 15% pathogenic bacteria, illnesses, and disease begin developing when increases in pathogenic bacteria create an imbalance in the microbiota (dysbiosis) (Wyatt, 2017). Cognitive development and microbial colonization occurs at the same time. At 2-3 years old the composition of the microbiota is like an adult (Dinan, et al., 2015).
Probiotics and bacteria that has improved microbial imbalances (dysbiosis) Lactobacillus and Bifidobacterium produce GABA, Lactobacillus produces acetylcholine and tryptophan is metabolized into kynurenine which Bifidobacterium can alter concentrations (Dinan, et al., 2015). In a mouse study of autism, TH1/TH2 imbalances were corrected with the treatment of Bacteroides fragilis and corrected intestinal permeability, increased cognition and behaviors including anxiety, communicative and stereotypic (Buie, 2015). ‘Probiotics Bifidobacteria and Lactobacillus, may reestablish the composition of the gut microbiome and exert benefits to gut microbial communities, leading to amelioration or prevention of gut inflammation and other intestinal or systemic diseases’ (Yang, Tian, & Yang, 2018).
Prenatal risk factors maternal immune factors
Researchers speculate unhealthy modern maternal diets have increased the rate of neurodevelopmental and childhood disorders (Bruce-Keller, Salbaum, & Berthoud, 2018). The risk of neuropsychiatric disorders in offspring increases with maternal diabetes and obesity and offspring can be affected in a sex-specific manner if maternal intestinal dysbiosis is caused by diet.
Maternal stress and immune activation can also negatively impact offspring’s behavior due to the alterations of the microbiome.
Prevention is possible with the administration of probiotics (Bruce-Keller et al.,2018).
The intestinal ecosystem is believed to start developing at or soon after birth ‘by vertical transmission and exposure to and/or ingestion of environmental flora’ (Bruce-Keller et al., 2018). 12-13% of individuals with ASD were born by C-section suggesting that maternal vaginal flora play a key role in the development of the microbiome and, subsequently, neurodevelopment as well (Buie, 2015). Disease can occur when there is a loss of the diversity of flora, loss of lactose fermenters and predominance of atypical microbes (Buie, 2015).
A rich and diverse microbiome can be achieved with eating a healthy diet with seasonal fruits and vegetables (Bruce-Keller et al., 2018). Studies found that high-fat diets in mice shaped a microbiome that disrupted exploratory, cognitive, and stereotypical/impulsive behaviors (Bruce-Keller et al., 2018). In mice studies, a decrease in the diversity of the intestinal microbiome was associated with continuous high-fat/low-fiber diet. Over generations this becomes irreversible. There is an increased risk of mental disorders linked to highly processed, poor quality foods that decrease the diversity of the microbiome (Bruce-Keller et al., 2018).
Autism runs on a spectrum with symptoms and severity of challenges with social skills, repetitive behaviors, speech and nonverbal communication. It is one of the most pervasive neurological disorder affecting 1 in 68 children and males are 4 to 5 times more likely to be affected (Buie, 2015). Autism is on the rise with the number of ASD diagnosis doubling in the last decade. It is one of the fastest growing, most commonly diagnosed neurological disorder. About 70% of the children diagnosed with Autism also have gastrointestinal issues (Bruce-Keller et al., 2018). A lot of research is currently being conducted looking into the gut-brain connection. Researchers speculate that neurologic developmental dysfunction of communication between the gut-brain axis due to the diversity of ones microbiome can influence autism (Bruce-Keller et al., 2018).
ASD and associated microbes
Wyatt (2017) purposes that nearly all autoimmune disease, psychiatric disorder, and cognitive decline can be traced back to poor gut health.
Researchers found distinctly less diverse microbiomes and low levels of Prevotella (is a bacteriod associated with good colon health), Corprococcus, and Veilonellaceae which ingest and ferment carbohydrates in children with ASD (Yang, Tian, & Yang, 2018). ‘An abundance of Firmicutes, low levels of Bacteroidetes, Actinobacteria and Proteobacteria, increased firmicutes/Bacteriodetes ratio, high levels of lactobacillus and Desulfovibri. Desulfovibri was positively correlated with the severity of ASD’ (Yang et al., 2018). When the ratio of Prevotella shift, increases in sutteralla have been seen (Ding, et al., 2017). Higher prevalence of Sutterella was found in half of children with ASD and GI issues but, not found in typically found in developing children that have GI issues (Ding et.al, 2017). Sutterella is closely related to other known pathogens and under certain circumstances can cause a variety of illnesses (Ding et.al, 2017).
Intestinal permeability (leaky gut syndrome, LGS) when treated with the antibiotic vancomycin showed short term behavioral and intestinal improvements (Buie, 2015).
Altered concentrations of SCFAs in feces are reported in ASD. Shank3 is a gene associated with neurodevelopmental disorders (autism) that can influence the microbiome and potentially be treated with probiotics.
Shank3 KO mice treated with L.ruteri reduced unsocial behaviors and decreased repetitive behaviors (Tabouy, Getselter, Ziv, Karpuj, Tabouy, Lukic, Elliott, 2018). There is a positive correlation between the presence of L. reuteri and expression of GABA receptor subunits in the brain. (Tabouy et al., 2018). In a mouse study of autism, TH1/TH2 imbalances were corrected with the treatment of Bacteriodes fragilis and corrected intestinal permeability, increased cognition and behaviors including anxiety, communicative and stereotypic (Buie, 2015).
Flyers advertising for the participation of 3-16 years of age with a diagnosis of ASD and accompanied by a typically developing siblings. The study will be sent out to all local schools and daycares, as well as being posted in online Autism forums. Interested candidates are instructed to send an e-mail to gain participation. Participants will be screened out of participation if either of the sibling pair has lactose intolerance. A sample size of 300 participants 150 children with ASD and 150 typically developing siblings.
The Behavior Assessment System for Children-Second Edition (BASC-2) assessing behavior and emotions ranging in age from 2 to 22 years old.
The Nisonger Child Behavior Rating Form (NCBRF) is a rating scale designed to assess children 3-16 years old on social competence and problem behavior in children with developmental disabilities. 16S rRNA gene sequence-based technique will be utilized to measure microbiota diversity.
Parents will sign consent form explaining the details of the study and may discontinue participation at any time. Parents will receive the following questionnaires through e-mail; The Behavior Assessment System for Children-Second Edition (BASC-2) and The Nisonger Child Behavior Rating Form (NCBRF). Parents will answer questions as to their child’s ASD diagnosis and asked to report any gastrointestinal issues before, during and at the end of the study. Siblings will be paired together, then randomly divided into three categories yogurt daily, which will be broken down into two subgroups; Bifidobacterium animalis (Activia) and Lactobacillus acidophilus, at least two healthy foods per meal group (limiting processed, high fat, low fiber foods in their diet and at least two different plant-based foods per meal), and the control with no change in diet.
Healthy diet group will need to keep a daily record for the child’s food intake for the duration of the study. Any changes in health are noted as well as any medications during the duration of the study for all participants. Caregivers are asked to forward on sections regarding observations from additional caregivers/teachers. A stool sample will be gathered from the participants before the beginning of the study.
All collected fecal samples will be analyzed as to its microbiome diversity and consistency with the use of ’16S rRNA gene sequence-based technique (Dinan et al., 2015). Paired sibling participants will be randomly assigned to Bifidobacterium animalis, lactobacillus acidophilus, healthy meals group, or the control. After a twelve-week period of eating either Activia that contains the bacteria Bifidobacterium animalis or Lactobacillus acidophilus (which can be found in Chobani, Dannon, Yoplait, Fage, Stoneyfield, and Siggi yogurts). Behavioral tests and a second stool sample will be collected at week 6 and again at week 12.
The greatest difference will be found in the healthy diet group especially in the youngest age category improving both GI issues and problem behaviors. There will be an increased diversity of microbiota for all participants in treatment groups resulting in improvements in GI issues and problem behaviors. Healthy diet will also significance between groups on decreasing GI issues and problem behavior.
There are at least a thousand times more microbes in the human microbiota than genomes on the human genome. As diverse as symptoms and severities of ASD are, so too will their microbiota be. In a study, children with ASD had higher concentrations of Clostridiales and lower levels of Prevotella and Coprococcus spp that compared unaffected siblings and unrelated controls, dietary behaviors weren’t to blame for microbial imbalances thought to be responsible for ASD (Buie, 2015). Despite Buie’s findings, a study of germ-free BALB/c mice that display behaviors associated with autism; social impairment and exaggerated caution, received a fecal microbial transplant from NIH Swiss mice who do not display said behaviors, normalized those behaviors in BALB/c mice.
Researchers have reported that probiotics used on animals ‘improved mood, anxiety, and cognition as well as a signaling and neural activity. In experimental studies ‘probiotics prevent stress-induced decreases in hippocampal neurogenesis and enhance expression of hypothalamic genes involved in synaptic plasticity’ (Bruce-Keller et al., 2018). Researchers saw a reduction in constipation and other gastrointestinal issues by 80% by transplanting beneficial micro-organisms into the gut of children with ASD (Duvauchelle, 2018). Future implications for this study would include implementing interventions geared at examining the diversity of the microbiome during Early Intervention, improving the lives of those with a diagnosis of ASD. The microbiota and cognition develop at the same time, by implementing detection and treatment in programs like Early Intervention for children who have microbiota dysbiosis could have positive life long effects.
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