Enigma of autism regression mechanistic pathways, clinical phenotypes, and early intervention implications

Table 3 Summary of mechanistic pathways in autism regression

Mechanism	Key feature	Clinical “red flag”
Neurobiological	Over-aggressive synaptic pruning	Loss of specific language/social skills
Immune	Microglial activation & neuroinflammation	Regression following illness or “brain fog”
Mitochondrial	Energy “power failure”	Extreme fatigue, low muscle tone, gastrointestinal issues
Gut-brain	Intestinal permeability & dysbiosis	Chronic constipation/diarrhea, food aversions
Epigenetic	Unmasking of latent genes	Sudden decline during the 15-30-month window