Viruses and autism: A Bi-mutual cause and effect

Table 1 The possible underlying mechanisms and triggering factors for autism

Possible mechanism	Effects
Immune dysregulation and autoimmunity	Neuroinflammation, cytokine dysregulation, and inducing anti-brain antibodies
Neuroinflammation	Neuroinflammation of the Cortex: Raised reactive microglial and astrocyte numbers → excess neurons → local overconnectivity in specific brain regions, abnormal neuronal migration during early pregnancy → abnormal synaptogenesis and formation of dendritic spines and disturbed excitatory-inhibitory networks, prominent brain volume and weight volume
	Neuroinflammation of brainstem → brainstem dysfunction → sensory processing abnormalities → enhanced sympathetic excitation and parasympathetic hypofunction
	Neuroinflammation of thalamus → autonomic nervous system dysfunction
Abnormalities in mirror neuron system regions	→ Impaired activation of the imitation core circuit → social impairment
Impaired signaling patterns in the cingulate cortex	→ Severely reduced cingulate self-response → social impairments
Autonomic nervous system dysfunction	Chronic sensory hyperarousal state in children and sleep disorders
	Affects heart rate, blood pressure, and respiratory rhythm
	Impaired gastrointestinal motility, gastric acid, and intestinal enzyme secretion
Underlying triggering factors	Maternal vitamin D deficiency, use of medication such as valproic acids during pregnancy, prenatal infection, neonatal hypoxia, preterm delivery, abnormal presentation, cesarean section, fetal complications, neonatal hypoxia, respiratory distress, natal bleeding, low-birth weight, seizures at birth, neonatal jaundice, early postnatal infection, sepsis, meningitis, encephalopathy, postnatal vitamin D deficiency
Augmenting factors	Gastrointestinal abnormalities, repeated infections with gut dysbiosis, and impairment of the gut-brain axis cause immune imbalance and trigger neuroinflammation