Childhood psychosis and monoamine metabolites in spinal fluid.

Doctors took a small sample of spinal fluid from children with autism, children with intellectual disability, and typical controls. They measured a brain chemical called homovanillic acid. The goal was to see if this chemical could tell autism apart from other delays.

Kids with autism and childhood psychosis had higher homovanillic acid levels. Kids with only intellectual disability did not. The marker looked specific to autism spectrum disorder, not to general cognitive delay.

Sun et al. (2015) later showed Chinese clinicians already diagnose autism with high accuracy using ADOS and ADI-R. Their work supports the idea that autism can be separated from other delays, but they used behavior tools, not spinal fluid.

Jiao et al. (2012) hunted a different kind of marker—29 gene variants—to predict autism severity. Their SNP panel reached only 67 % accuracy, weaker than the clean split Gillberg et al. (1983) saw with the metabolite.

Together these papers show the field has moved from body fluids to genes to behavior checklists, yet all chase the same goal: an objective way to spot autism and rule out plain intellectual disability.

You still can’t order a spinal tap at your clinic, but the finding reminds you that autism carries biology you can’t see. When a child shows social gaps yet scores in the ID range, trust that the two conditions can coexist. Keep using gold-standard ADOS/ADI-R tools, and note that newer genetic screens add only modest power. For now, sharp observation remains your best early marker.