• Subtypes of thought disorder and affective flattening were examined in 14 adults with clear DSM-III diagnoses of infantile autism or autism, residual state, using videotaped psychiatric interviews and objective rating scales. Schizophrenic, manic, and normal subjects constituted contrast groups. Autistic adults, most of whom were high functioning, showed a high incidence and severity of poverty of speech, poverty of content of speech, perseveration, and affective flattening. They showed significantly less derailment, illogicality, and other features of "positive thought disorder" than either the schizophrenic or manic group, but they did not differ from schizophrenics on any affective flattening variable.
Rumsey JM, Andreasen NC, Rapoport JL. Thought, Language, Communication, and Affective Flattening in Autistic Adults. Arch Gen Psychiatry. 1986;43(8):771–777. doi:10.1001/archpsyc.1986.01800080057008