Aggression – Root Causes and Solutions

Aggression in autism is often seen as a “part of autism”. Very rarely are any medical investigations carried out to ascertain if there may be a root cause to what seems to us as a behavioural issue. Our children don’t harm themselves or others or behave aggressively towards others for no reason. It is their way of communicating.


Children and adults with autism are at a much higher risk of suffering from various medical conditions and consistently face barriers in accessing appropriate medical care. Centres have corroborated the high prevalence of comorbidity for Disease Control and Prevention and by large-scale studies examining the records of 2.5 million adult autism patients. Individuals with autism experiencing pain or discomfort may not be able to identify the physical location of that pain/discomfort within their bodies. They often have their symptoms dismissed. Conditions can include persistent upper respiratory infections, dental pain, ear and sinus infections, food and inhalant allergies, asthma and atopic dermatitis, gastrointestinal issues, sleep disturbances, headaches and migraines, epilepsy, hearing and vision impairment, auto-immune conditions, hypertension, and type 1 diabetes. For some in extreme discomfort, these conditions can manifest in aggressive outbursts. A recent example in our clinic was a 17-year-old man with severe autism and a history of unexplained aggression. He was found to have a Helicobacter Pylori infection. Once the infection was eradicated, the aggressive behaviour stopped.



Gastrointestinal (GI) issues are significantly over-represented in autism. They can often be related to problem behaviours, including aggression, OCD, sensory processing difficulties, anxiety, irritability, and dysregulated sleep. Common GI issues include constipation, diarrhoea, reflux, microbiome imbalances, and enzyme deficiencies. A non-verbal 7- year-old boy with chronic constipation and significant behavioural problems, including biting himself and others, was assessed by our clinic. He was given appropriate supplements to help with constipation, and lab tests showed dairy intolerance, which was removed from the diet. He opened his bowels daily within four weeks, and aggressive outbursts reduced significantly.



This has to be one of the most significant imbalances in the children we assess. Kids addicted to carbohydrates, and refined sugar often have blood sugar that goes super high and then crashes throughout the day. If any of you have ever felt “hangry”, you will have a small insight into the world of someone with uncontrolled blood sugar balance. Simply put, ensure you always eat carbohydrates with protein and healthy fat – this will slow down digestion and release the sugar from the carbohydrates into the bloodstream more steadily. Starting your day with a breakfast full of protein and fat instead of the usual carb-heavy one of cereal and milk is so important. Once blood sugar swings out of balance, it’s hard to get it back under control. A full-fat yoghurt with berries, nuts, or seeds is a good swap for cereal. Remember there’s no such thing as ‘breakfast food’, so if your child wants sausages with some veg for breakfast, that’s great!

We know parents have to rely on packaged foods sometimes, and these are often very high in sugar and carbs. A simple hack is to ensure that the carbohydrate to protein ratio is no more than 5:1. For instance, a ‘cereal bar’ with 25g of carbs should contain at least 5 grams of protein to balance it out.



Infections can be gastrointestinal-based with yeast and bacterial overgrowth, for instance, or they can take the form of a persistent streptococcal infection. We often find that additional viral issues contribute to mood instability and behavioural symptoms when we look closer. Appropriate tests can help ascertain the infectious agents, which are addressed with a combination of medical and biomedical approaches. Marcus, an 8-year-old autistic patient of ours, had become increasingly uncooperative and aggressive over a two-to-three-year period following a viral illness at age 5. Tests revealed that he had raised antibodies to streptococcal bacteria and signs of reactivation of Epstein Barr virus. Working with a medical team, we found the usual antibiotics did not make a difference. He subsequently underwent a tonsillectomy which improved his symptoms significantly. His symptoms were almost entirely gone within six months with dietary changes and micro-immunotherapy.



IgE and non-IgE mediated allergic reactions are recognised causative factors of anxiety and mood disorders, including aggressive behaviour. Other key symptoms include the inability to fall asleep, hyperactivity, daytime fatigue, poor focus and concentration, and excessive sweating. Checking for celiac disease should be standard, but it is also important to note the issues of non-celiac gluten sensitivity, which is increasingly recognised. Enzyme deficiency can be an issue in a significant number of children. In a subset of children, an adequately monitored diet without gluten and often without dairy has reduced symptoms and sometimes alleviated them completely. Removing food colourings, additives, and phenol-containing foods (found in berries, apples, tomatoes, cheese and many other coloured fruits and vegetables) can be a complete game-changer. You will find a detailed article about the impact of phenols and salicylates on behaviour, sleep, and cognition in the spring 2021 edition of the Autism Eye magazine. A 5-year-old girl with regressive autism came to us with episodic aggressive outbursts, frequent night-waking, and very smelly stools. Tests revealed high non-IgE reaction to gluten, dairy and soya. Within six weeks of removing the offending foods, sleep and bowel movements normalised, and aggressive outbursts were almost entirely resolved.



It will come as little surprise that many individuals with autism have pronounced fight-or-flight responses. They can react in what seems like an exaggerated way to situations, and it can take them a long time to calm their nervous system down. This can be partly due to genetic polymorphisms responsible for processing stress hormones. But often, the body is under constant stress from chronic infections, gut dysbiosis, food allergies, immune dysregulations, and nutrient deficiencies. Assessing and addressing the root contributors to the stress response is the only way to get long-term gain and reduce and, in some cases, completely alleviate symptoms. Our clinic assessed a 16-year-old girl diagnosed with autism and PANDAS; She suffered from depression, anxiety and aggressive outbursts, which had become increasingly pronounced over the previous three years. She was found to have low ferritin, vitamin D, and extremely low levels of lithium and other minerals. She was also found to have significant intolerance to eggs. Removing the problem food, replenishing missing nutrients and using adrenal-supportive supplements turned things around for this young person within two weeks.



There are several other considerations. Absent seizures, reactions to medications, low cholesterol, auto-immune conditions, mitochondrial disorders, and cerebral folate deficiency, all of which can contribute to aggressive outbursts and mood disorders. In this article, I have highlighted the most common findings in our practice. To learn more, visit and


Behaviours that may indicate an underlying illness, pain or discomfort

  • Loss of previously acquired skills
  • Sudden change in behaviour
  • Irritability and low mood
  • Tantrums and oppositional behaviour
  • Frequent night-waking
  • Teeth grinding
  • Changes to appetite or food choices
  • Heightened anxiety
  • Avoidance behaviours
  • Sensory hyper-responsivity
  • Walking on toes
  • Posturing/seeking pressure to specific areas
  • Behaviour around evacuation
  • Aggression: onset or increase in
  • Facial grimacing
  • Self-injurious behaviour
  • Constant eating/drinking
  • Frequent clearing of throat/swallowing
  • Mouthing behaviours: chewing on non-food items
  • Repetitive rocking or other repetitive movements
  • Sobbing “for no reason”
  • Vocal expression: moaning, grinding, sighing, whining
  • Agitation: pacing, jumping up and down
  • Blinking excessively
  • Sudden screaming intermittently
  • Spinning
  • Fixed, glazed look.
Source: Medical Comorbidities in Autism Spectrum Disorders. A primer for Health Care professionals and Policy Makers. Second Edition. Prepared by Thinking Autism, ESPA Research and Autism Treatment Plus.



Isaksen, J., Bryn, V., Diseth, T.H., et al. (2012) Children with autism spectrum disorders–The importance of medical investigations. Eur J Paediatr Neurol. 17:(1):68-76.
Jones, S., Howard, L. and Thornicroft, G. (2008) ‘Diagnostic overshadowing’: worse physical health care for people with mental illness. Acta Psychiatr Scand. Sep;118(3):169-71.
Kanne, S.M. and Mazurek, M.O. (2011) Aggression in children and adolescents with ASD: Prevalence and risk factors. J Autism Dev Disord. 41:(7):926-937.
Khandaker, G.M., Zammit, S., Lewis, G., et al. (2014) A population-based study of atopic disorders and inflammatory markers in childhood before psychotic experiences in adolescence. Schizophr Res. 152(1):139-45.
Libbey, J.E., Sweeten, T.L., McMahon, W.M., et al. (2005) Autistic disorder and viral infections. J Neurovirol. 11:1-10.
Schieve, L.A., Gonzalez, V., Boulet, S.L., et al. (2012) Concurrent medical conditions and health care use and needs among children with learning and behavioral developmental disabilities, National Health Interview Survey, 2006–2010. Res Dev Dis. 33:(2):467-476.
Adams, J.B., Johansen, L.J., Powell, L.D., et al. (2011) Gastrointestinal flora and gastrointestinal status in children with autism- -comparisons to typical children and correlation with autism severity. BMC Gastroenterol. 11:(1):22.
Buie, T., Fuchs, G.J., Furuta, G.T., et al. (2010) Recommendations for evaluation and treatment of common gastrointestinal problems in children with ASDs. Pediatrics. 125 Suppl 1: S19-S29.
Coury, D.L., Ashwood, P., Fasano, A., et al. (2012) Gastrointestinal conditions in children with autism spectrum disorder: developing a research agenda. Pediatrics. 130: (Supplement 2): S160-S168.
Ghaziuddin, M., Al-Khouri, I. and Ghaziuddin, N. (2002) Autistic symptoms following herpes encephalitis. Eur Child Adolesc Psychiatry. Jun;11(3):142-6.
Goehler, L.E., Gaykema, R., Opitz, N., et al. (2005) Activation in vagal afferents and central autonomic pathways: Early responses to intestinal infection with Campylobacter jejuni. Brain Behav Immun. 19:(4):334- 344.
Goncalves, M.V.M., Harger, R., Braatz, V., et al. (2018) Pediatric acute-onset neuropsychiatric syndrome (PANS) misdiagnosed as autism spectrum disorder. Immunol Lett. 203:52–53.
Kohman, R.A., Hash-Converse, J.M. and Kusnecov, A.W. (2009) Effect of Systemic Challenge with Bacterial Toxins on Behaviors Relevant to Mood, Anxiety and Cognition. In Siegel, A. and Zalcman S, eds.: The Neuroimmunological Basis of Behavior and Mental Disorders. 183-208.
Orlovska, S., Vestergaard, C.H., Bech, B.H., et al. (2017) Association of Streptococcal Throat Infection With Mental Disorders: Testing Key Aspects of the PANDAS Hypothesis in a Nationwide Study. JAMA Psychiatry. 74(7):740–746.
Angelidou, A., Alysandratos, K.D., Asadi, S., et al. (2011) Brief Report: “Allergic Symptoms” in Children with Autism Spectrum Disorders. More than Meets the Eye?. J Autism Dev Disord. 41:(11):1579-1585.
Boris, M. and Goldblatt, A. (2004) Pollen exposure as a cause for the deterioration of neurobehavioral function in children with autism and attention deficit hyperactive disorder: nasal pollen challenge. Journal of Nutritional and Environmental Medicine. 14:(1):47-54.
Caio, G., Volta, U., Tovoli, F., et al. (2014) Effect of gluten free diet on immune response to gliadin in patients with non-celiac gluten sensitivity. BMC Gastroenterol. Feb 13;14(1):26.
Chen, M.H., Su, T.P., Chen, Y.S., et al. (2013a) Comorbidity of allergic and autoimmune diseases in patients with autism spectrum disorder: A nationwide population-based study. Res Autism Spect Dis. 7:(2):205- 212.
Li, H., Liu, H., Chen, X., et al. (2020) Association of food hypersensitivity in children with the risk of autism spectrum disorder: a meta-analysis. Eur J Pediatr. Nov 4.
Ramaekers, V.T., Sequeira, J.M., Blau, N., et al. (2008) A milk-free diet downregulates folate receptor autoimmunity in cerebral folate deficiency syndrome. Dev Med Child Neurol. May;50(5):346-52.
Anderson, C.J., Colombo, J., Unruh, K.E., et al. (2013) Pupil and salivary indicators of autonomic dysfunction in autism spectrum disorder. Dev Psychobiol. Jul;55(5):465-82.
Eilam-Stock, T., Xu, P., Cao, M., et al. (2014) Abnormal autonomic and associated brain activities during rest in autism spectrum disorder. Brain. Jan;137(Pt1):153-71
Frye, R.E., Sequeira, J.M., Quadros, E.V., et al. (2013b) Cerebral folate receptor autoantibodies in autism spectrum disorder. Mol Psychiatry. 18(3):369–381.
Chen, S.W., Zhong, X.S., Jiang, L.N., et al. (2016) Maternal
autoimmune diseases and the risk of autism spectrum disorders in offspring: A systematic review and meta-analysis. Behav Brain Res. 296:61–69.
Goh, S., Dong, Z., Zhang, Y., et al. (2014) Mitochondrial Dysfunction as a Neurobiological Subtype of Autism Spectrum Disorder: Evidence From Brain Imaging. JAMA Psychiatry. Jun;71(6):665-71.
Modabbernia, A., Velthorst, E., Reichenberg, A., et al. (2017) Environmental risk factors for autism: an evidence-based review of systematic reviews and meta-analyses. Mol Autism. Mar 17;8:13..
Rossignol, D.A., Genuis, S.J. and Frye, R.E. (2014b) Environmental toxicants and autism spectrum disorders: a systematic review. Transl Psychiatry. Feb 11;4:e360.