Sensory and behavioural problems in Autism and related ASDs occur when blood circulation and oxygen delivery through the areas of the brain that control our emotions, called collectively the limbic system, is abnormal.
The limbic system also alters the breathing pattern in response to emotion including feelings such as happiness, fear, anger, frustration and rage. Emotion such as anxiety, excitement and rage produce shallow fast upper thoracic breathing and breath holding. This kind of breathing reduces oxygen to the brain and is normally quickly compensated for by a shift to diaphragmatic breathing.
Children with autism and related ASDs tend to be upper thoracic breathers and do not revert to normal diaphragmatic breathing after a stressful episode. The lower part of the lungs close to the diaphragm is the richest in blood vessels allowing more oxygen to be absorbed into the bloodstream during diaphragmatic breathing.
Persistent upper thoracic breathing reduces supplies of circulating oxygen to vulnerable areas in the brain. This slows down the removal of metabolic waste by-products such as lactic acid and steadily disrupts the balance between oxygen and carbon dioxide (CO2). Furthermore, both pH levels and free radical activity in the lungs, the circulating blood and the mitochondria are also negatively impacted.
The result is a negative loop in which the stronger the emotion the faster and shallower the breathing becomes and as a consquence the behaviour worsens (also known as a Meltdown). As long ago as 1967 the ‘New England Journal of Medicine’ reported results linking lactic acid to anxiety attacks.