References: Autism, ADHD, and the Gut

1. Autism Spectrum Disorder - National Institute of Mental Health (NIMH) - A plain-language guide to what autism is, common strengths and challenges, what is known about causes, and how diagnosis works. Source for the description of autism and its known influences in Section 13.2.

2. Attention-Deficit/Hyperactivity Disorder: What You Need to Know - NIMH - Explains the three patterns of ADHD, how it is diagnosed, and what research says about causes (genes play a large role). A good antidote to "sugar causes ADHD" posts.

3. Prevalence and Early Identification of Autism Spectrum Disorder Among Children Aged 4 and 8 Years, 2022 - Shaw KA, et al., CDC MMWR Surveillance Summaries, 2025 - The CDC's most recent autism monitoring report, which estimated that about 1 in 31 eight-year-olds at 16 US sites had been identified as autistic in 2022.

4. Gastrointestinal Symptoms in Autism Spectrum Disorder: A Meta-analysis - McElhanon BO, et al., Pediatrics, 2014 - Pooled 15 studies showing higher odds of GI symptoms, constipation, diarrhea, and belly pain in autistic children. The data in Your Gut Check question 5 come from this paper.

5. Autism-Related Dietary Preferences Mediate Autism-Gut Microbiome Associations - Yap CX, et al., Cell, 2021 - The 247-child study that found negligible direct links between autism and the microbiome, with diet explaining most of the differences. The central study behind the Confounder Detective.

6. Multi-level Analysis of the Gut-Brain Axis Shows Autism Spectrum Disorder-Associated Molecular and Microbial Profiles - Morton JT, et al., Nature Neuroscience, 2023 (free full text) - Pooled many data sets and found autism-linked patterns that disappeared in sibling comparisons. A useful contrast to read alongside Yap 2021.

7. Microbiota Transfer Therapy Alters Gut Ecosystem and Improves Gastrointestinal and Autism Symptoms: An Open-Label Study - Kang DW, et al., Microbiome, 2017 (free full text) - The 18-child open-label trial analyzed in the chapter's claim box. Read the limitations section, where the authors explain why a placebo-controlled trial is needed.

8. Effect of Oral Faecal Microbiota Transplantation Intervention for Children with Autism Spectrum Disorder: A Randomised, Double-Blind, Placebo-Controlled Trial - Wan L, et al., Clinical and Translational Medicine, 2024 (free full text) - A placebo-controlled trial of 103 autistic children that found no significant difference from placebo on its main measure, and a large placebo effect.

9. Avoiding Ableist Language: Suggestions for Autism Researchers - Bottema-Beutel K, et al., Autism in Adulthood, 2021 (free full text) - Drawing on autistic scholarship, explains why some language treats autism as a defect and suggests respectful alternatives. The basis for this chapter's language choices.

10. Microbiota Modulate Behavioral and Physiological Abnormalities Associated with Neurodevelopmental Disorders - Hsiao EY, et al., Cell, 2013 - The maternal immune activation mouse study discussed in Section 13.6. A good example of clever mouse research whose results can't be applied directly to people.

11. A Systematic Review on the Associations Between Attention-Deficit/Hyperactivity Disorder and Gut Microbiome - Dias MF, et al., Journal of Psychiatric Research, 2025 - Summarizes 14 small studies (1,319 participants) on ADHD and gut bacteria and finds diversity results inconclusive.

12. The Effect of Sugar on Behavior or Cognition in Children: A Meta-analysis - Wolraich ML, et al., JAMA, 1995 - Pooled 23 blinded studies and found that sugar did not affect children's behavior or thinking. A classic lesson in why blinding matters.