Is autism having a moment? Two new books examining its history, both more than 500 pages, would certainly seem to indicate that it is. A few months after the publication of Steve Silberman’s Samuel Johnson prize-winning Neurotribes, another detailed examination of autism’s complex evolution appears in bookshops. In a Different Key: The Story of Autism covers some of the same ground – the debates about defining and diagnosing a condition that still has no clear biological markers, the consequent anxiety about whether autism is actually on the increase and, if so, what could be the causes and what are the best ways to educate and accommodate people on the spectrum over their lifetime.

Like Silberman, the two authors, Caren Zucker and John Donvan, are American journalists who have spent many years researching their book. In 2010 they wrote an excellent article in the Atlantic magazine in which they tracked down one of the first children to be diagnosed with autism in 1943. The fascinating life story of Donald Triplett, now in his 80s, bookends In a Different Key, which also draws on the authors’ extensive experience as producers who regularly deliver reports on all aspects of autism for ABC television in the US. Each chapter finishes with a tantalising hint at the contents of the next, as if the text adheres to television’s “coming up after the break…”.

The authors delve into the dark era of institutionalisation, stories of rival American autism charities and their campaigns for schooling, rights and research. The often toxic infighting between charities, educationalists, researchers, parents and activists is examined at exhaustive length. There is a familiar account of the bad science that led to the panic around MMR on both sides of the Atlantic as well as less well-trodden tales of unethical researchers in the 1960s giving huge doses of LSD to autistic children. In a Different Key is very much an evaluation of autism’s history from an English-language perspective, with very little attention to the pioneering work done in northern Europe. There’s also an assumption that all is now well with the treatment of autistic people. They write that the “cruelty and neglect that have marked the history of autism now seem antiquated” – when this is far from the case in much of the world.

Despite their long interest in the subject, and personal connection (both Zucker and Donvan have family members with autism), it is sometimes hard to ascertain their key objectives in writing In a Different Key. Quality broadcasters are professionally bound to balance their reporting, but choosing which story to tell, how interviews are edited and who gets the last word usually hints at the producers’ personal take. In Neurotribes, Silberman made it clear his aim was to show that autistic people have always been with us and can contribute greatly to society if only society can learn to accommodate them better. Donvan and Zucker’s message is less clear. In a Different Key tends to chronicle darker moments from the history of autism – the damaging fraud of facilitated communication perpetrated on autistic people who cannot speak, the father who murdered his autistic son because he feared his sexual exhibitionism would lead to institutionalisation. These are grim tales.

Behind the journalistic colour and dramatisation in their descriptions of parents’ meetings and professionals’ breakthroughs, there is a frustrating tendency to hide the authors’ personal opinions on where research should be concentrated and what therapies work. For example, one of the most popular interventions for autism is applied behavioural analysis (ABA), which, its proponents maintain, can help an autistic child lose their self-absorbed, repetitive (and sometimes self-harming) behaviours and replace them with greater social interaction and the capacity to learn new skills. But ABA’s harsher critics liken it to dog training and a desire to make autistic people appear superficially normal (no hand-flapping permitted) rather than allowing them their self-soothing rituals. Donvan and Zucker detail the development of ABA by its originator, Ivar Lovaas, a charismatic Norwegian-American psychologist who used electric shocks, shouting and corporal punishment in the 1960s on autistic children. They describe Lovaas as an arrogant man who made unsubstantiated claims for ABA’s success and go into detail about his sexual proclivities, but then cite the many parents who believe that ABA (in a modified form) has “recovered” their children from autism. Is this a case of love the message but not the messenger?

If it’s unclear how exactly Donvan and Zucker rate Lovaas’s worth in the history of autism, it is abundantly obvious how they view another key figure, Hans Asperger. The Austrian paediatrician is credited with coining the term “autistic” in 1943 – simultaneously with Leo Kanner in the US. Drawing on archival documentary material discovered by an Austrian historian – which at the time of writing this review is not in the public domain for first-hand interpretation – Asperger is presented not as the kindly paediatrician doing his best to protect his unusual, autistic child patients by talking up their potential, but as a doctor who was compliant with the Nazi policy of killing its “unproductive” disabled citizens in the name of eugenics. In a Different Key details how Asperger’s signature appears on orders to send profoundly disabled children in his care to a Viennese hospital where it was well known that a punitive drug regime would lead to their early death.

Neither Silberman in Neurotribes nor the British autism researcher Adam Feinstein in his A History of Autism (2010) have had access to this wartime archival material and instead judge Asperger very positively on his lifetime’s work advocating and enabling the sympathetic education of autistic children. This new description of Asperger’s actions during the Nazi era is the scoop in Zucker and Donvan’s book and will doubtless lead to much discussion and reassessment, especially when the documentation becomes accessible.

Whether Asperger was a saint or a sinner should not dominate the discourse around autism, which could better concentrate on whether the concept of autism as a single entity has had its day. What is striking in Neurotribes and In a Different Key is how experts have struggled for 70 years to define a condition that is so varied in impact and can describe both the eccentric, antisocial genius and the mute, self-harming child. In 1966, Victor Lotter carried out the first epidemiological study in the UK and wrote: “True prevalence may not be a useful concept in the case of a syndrome so poorly defined.” He found that 4.5 children in 10,000 had autism. In a Different Key cites a one in 68 figure, raising the question, if autism is indeed having a moment, what exactly are we calling autism in 2016? Perhaps it is time to talk about “autisms” in the plural, a constellation rather than a spectrum, as some researchers have suggested.

In a Different Key is published by Allen Lane (£20). Click here to buy it for £16