If you have an autistic child, chances are you’ve noticed your child often displays physical and behavioral signs of anxiety such as restlessness, recurring headaches, withdrawing from family or refusing to go to school. Unfortunately, anxiety is a common occurrence in autism – according to a research paper published in Neuropsychiatry, “up to 80% of children with ASDs experience clinically significant anxiety, with high comorbidity rates for social phobia, generalized anxiety disorder (GAD), obsessive-compulsive disorder (OCD) and separation anxiety disorder (SAD) (30, 35, 37 and 38%, respectively).” 
Children with autism are often very stressed by their environment; this can be one cause of increased anxiety. They may have sensory processing disorder – crowded spaces, loud noises, and bright lights of a shopping center or public event can constitute an assault to their system and cause their body to go into fight or flight mode. Doing normal everyday things can cause anxiety for them. And this decreases their ability to manage stress and thus leads to increased anxiety.
Social interactions are often an issue for children with autism – this can explain why these children commonly have difficulty establishing and maintaining relationships. Add anxiety to the equation and the child will have increased ASD symptom severity as well as greater impairments in sociability. What this means is that those children with autism who also have anxiety are likely to struggle even more with their social environment and interactions
Biochemical aspects of anxiety
1. Chronic inflammation
2. Decreased methylation function
3. Altered dopamine signaling
4. Increased intestinal permeability
5. High levels of HPHPA
6. High levels of glutamate
7. Presence of cerebral folate receptor autoantibodies
9. Food reactions
To help you better understand why anxiety is such an issue for individuals with autism, this article will cover the biochemistry of anxiety in autism and what you can do.