The incidence of autism has risen fourfold over the last few decades. Scientists have sought the cause in physical, chemical and biological agents, including, notoriously, vaccines. But many have suspected that the whole thing is an artefact of labelling – labelling cases that would otherwise not have receive a label, or re-labelling other conditions as autism. It turns out that approximately two-thirds of the increase can be accounted for by re-labelling alone. In an ingenious study, investigators analysed all American children enrolled in special educational programmes, all of whom are recorded (as required by law) on a national database. An increase in ‘autism’ was largely offset by a corresponding decline in other stated categories of disability. I am afraid that psychiatric diagnoses will be dominated by ephemeral factors until it is based on underlying biology. Reductionism has a bad name in some circles, but the search for deterministic explanations of human mental diseases is the remaining frontier for medical discovery. Will molecular genetics and functional MRI get us there, or do we need another fundamental breakthrough, as suggested in a previous post?
— Richard Lilford, CLAHRC WM Director
- Polyak A, Kubina RM, Girirajan S. Comorbidity of intellectual disability confounds ascertainment of autism: implications for genetic diagnosis. Am J Med Genet B Neuropsychiatr Genet. 2015. [ePub].