Currently, one in 59 children (1.7%) are being diagnosed with Autism spectrum disorder (ASD). During the 1960s, one in 250 (0.4%) were diagnosed with autism. This apparent 420% increase in reported cases is largely due to misdiagnoses occasioned by changing criteria. Phenotype diagnosing has been abandoned in favor of ticking off symptoms on a checklist with minimal understanding of cause and effect. Dissimilar conditions are now being included under a broad ASD umbrella category. This study explains the unique neurophysiological cause of autism, redefines autism in terms of this unique cause, and provides differential diagnostic criteria plus a litmus test that enables you to know for certain if someone suspected of being autistic has been correctly diagnosed.