In nursing homes across the Third Reich, children diagnosed with “autistic spectrum disorder” (as it might be termed today) were systematically murdered. Caring for these “useless mouths” drained the Aryan state. It was best they died by lethal injection (the so-called “nursing cure”). Not all Nazi attempts to cleanse society medically resulted in murder. In Vienna during the Anschluss, Austrian paediatrician Hans Asperger had begun to view autism as a developmental condition rather than a form of “idiocy” to be eradicated. The juveniles in his care exhibited strange behavioural traits such as hand- flapping and other forms of “stimming” (repetitive body movements) that required unorthodox teaching methods commensurate with their “psychopathy”. In popular legend, Asperger was an Oskar Schindler figure who shielded his charges from euthanasia.

At the same time in 1940s America, coincidentally, child psychiatrist Leo Kanner claimed autism was a form of childhood schizophrenia brought on by emotionally deficient parents. Kanner’s talk of “refrigerator mothers” served largely to stigmatise the condition as shameful. (Autistic children were taken from their parents and shut away in state institutions.) Independent of each other, Kanner and Asperger had found new ways of looking at infantile autism. Asperger emphasised the potential benefits for society to be had from the unique intelligence of his “little professors”. Their tunnel-like focus on minutiae was often accompanied by an unconventional logic and bracingly skewed way of looking at the world. In his estimation, autism was at once a disability and a gift.

Asperger’s ideas, decades ahead of their time, were taken up in the 1970s by researchers at the Maudsley psychiatric hospital in south London. Among them was the pioneering British psychiatrist Lorna Wing, later one of the founding intellects of what was to become the British National Autistic Society. In 1981, Wing introduced the term “Asperger syndrome” to denote the presence of “higher functioning” children among her patients. The term is widely used today, not least by parents who find Asperger’s a more acceptable diagnosis than classic autism, with its association of muteness, physical disability and social withdrawal. Yet Wing, who died in 2014, seems not to have got the measure of Asperger, whom she met only once, not long before he died in 1980. Of his private life all she knew was that he was a practising Catholic who had declined to join the Nazi party. But that was enough to sway Wing: while Nazism scorned Judaeo-Christian compassion for the weak and vulnerable, the devout Christian Asperger saw a kind of otherworldly grace in “neurodiversity”. Not surprisingly he became a leading light in the autistic rights movement, which to this day argues that the autistic mind is “different, not less”.

However, Asperger may not have been all that Wing took him to be. According to US historian Edith Sheffer, he wrote fatally damning reports on at least 42 of his child patients. In the Nazi formulation they were “lives unworthy of life”. His signature is on paperwork that transferred them to Vienna’s infamous Am Spiegelgrund clinic, where almost 800 inmates were murdered. With their lack of apple-cheeked health and “community connectedness” the children threatened to drag down the Volk. Asperger surely knew of their probable fate; the Spiegelgrund euthanasia programme caused a public outcry.

Asperger was typical of what Sheffer calls the Third Reich’s “diagnosis regime”. Racial characteristics, religion and physical disabilities were all set down with lapidary coldness on index cards and stored in files. Nazism depended on a nationwide conformism and sense of belonging; and autistic children, by their manifest oddness, were at loggerheads with Hitlerite ideals of social cohesion and community-minded Gemüt or “soul”. Asperger was not a zealous supporter of the Nazi regime, but inevitably nazism implicated him in what Primo Levi called “grey zones” of compromise. Medicine was one of the most nazified professions in the Third Reich, so it was a rare doctor who escaped the Nazi influence. Asperger’s life story, as Sheffer relates it, was not untypical of young Austrian doctors in 30s and early 40s Vienna. Not only did he work as a psychiatric expert for the city’s Nazi-run juvenile court system, he applied to act as a consultant for the Hitler Youth. Ultimately, he was less infamous than inadequate. He may have shut off part of his conscience, but can he be accused of having no conscience at all? The humanity he showed a number of children in his care was insufficient and possibly guilt ridden, yet still it was humanity. If anything, Asperger had a specialist’s tunnel vision; he viewed his work chiefly in terms of his own special competence (autistic psychopathy) and so was able to ignore its larger moral consequences.

The term Asperger syndrome is likely to persist, Sheffer concludes, even though in 2013 it was dropped from the US psychiatric handbook The Diagnostic and Statistical Manual of Mental Disorders. Asperger’s recognition of the benefits of “neurodiversity” should not blind us to the difficulties faced by autistic people. My teenage son has a diagnosis of Asperger syndrome. Depression alternates in him with levels of anxiety and physical violence born of frustration. For three years he refused to attend mainstream school. During the long years of school-refusal he was prescribed anti-psychotics. My wife and I sustained endless but usually fruitless consultations with paediatricians, psychologists, neurologists, social workers and, on four occasions, the police. We spent thousands of pounds on solicitor’s fees: the London borough where we live failed to provide adequate education, so we took them to court. It is small wonder that autism can drive families apart. Hans Asperger may or may not have looked kindly on my son.

• Asperger’s Children: The Origins of Autism in Nazi Vienna is published by Norton. To order a copy for £20 go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99.