There are several neuromediators, which were found to be disturbed in ASD children. Mostly, the disturbance occurs due to DNA methylation and disturbance in the immune system. Neuromediators affect brain development, starting from the prenatal period, and because of the interconnection of the immune and neuroendocrine systems, they alter the immune function.

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Serotonin

The first neuromediator is serotonin (5HT), which was shown to be elevated in the brain of children with autism. Serotonin is an important agent in brain development, imbalance of which affects atypical brain development. Additionally, serotonin affects behavior and controls growth. 

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Serotonin level is altered in ASD children due to DNA alteration. The coding variant of the SERT gene was found to be altered in ASD individuals. At the same time, serotonin affects the function of the immune system.

 

Apart from the genetic causes, the level of serotonin may also be altered as a result of inflammation and infection. This means that disturbances to the immune system cause alterations in the neuroendocrine system, and alterations in the neuroendocrine system result in disturbance to the immune system.

 

Melatonin

Sleep disturbance is one of the symptoms that is often present in children with autism. One of the main reasons is an imbalance between serotonin and melatonin levels. Melatonin is produced from serotonin, and sometimes the child may have elevated serotonin levels and decreased melatonin levels. While serotonin is responsible for daily activity, melatonin is responsible for sleep at night. Children who have such a disbalance are hyperactive and have sleep problems.

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If serotonin level may be altered due to inflammation and genetic changes, melatonin level is altered due to serotonin elevation.

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Oxytocin 

One more hormone imbalance that has been associated with ASD is oxytocin. One study showed that the level of oxytocin is significantly reduced in ASD children, and this correlates with the extent of social communication skill impairment. Studies indicate that oxytocin deficiency is mainly caused by genetic factors.

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So, as well as serotonin, oxytocin may be imbalanced due to genetic changes resulting from inflammation, and this imbalance, in turn, negatively affects the immune system function.