Diseases that have no objective tests to distinguish them from normality have a tendency to spread like fungus: for example, it is years since I heard anyone say that he was unhappy rather than depressed, and it cannot be a coincidence that 10 percent of the populations of most western countries are now taking antidepressants. Yet the state of melancholia undoubtedly exists, as anyone who has seen a case will attest.

Likewise with autism. I remember an isolated, friendless and uncommunicative patient who tried to kill himself when his landlord could no longer tolerate the collection of light bulbs that he had collected since childhood, was constantly enlarging, and that now threatened to fill the whole house. For the patient light bulbs were the meaning of life. It was difficult to believe in such a case that there was not something biologically wrong with the patient, even if one could find it.

An editorial in the New England Journal of Medicine traces the convoluted history of the diagnosis of autism and Asperger’s syndrome. The pediatricians Leo Kanner and Hans Asperger described the conditions in 1943 and 1944, respectively.

Kanner thought that two features were essential to autism, a psychological separation from the world manifest very early in a child’s life and an obsessive desire to prevent change in the person’s immediate surroundings. Kanner thought that such children had similar parents, often of high intelligence but who were better and happier with ideas than with human relationships. This gave rise later to the concept of the “refrigerator mother,” that is to say a cold and uncommunicative woman who did not cuddle her child or provide it with any emotional warmth, and whose conduct caused the child, by a mechanism of defense, to withdraw into its own world. This was also the era of the “schizophrenogenic” mother, the mother who communicated two messages in one verbal utterance, leaving the child uncertain as to what was meant.

These theories have now been abandoned; they were not only wrong but cruel, for they blamed the mother for the child’s devastating condition. Biology is back in fashion.