TLDR
The study counted children with autism and related conditions across Wisconsin rather than relying on one clinic. It showed that autism was diagnosed in fewer than one child per 10,000 children at that time.
Summary
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1 Study Aim
The authors aimed to measure the incidence (newly identified cases) and prevalence (all identified cases) of childhood schizophrenia and infantile autism among Wisconsin children aged 12 and under. They also sought to compare these cases with earlier reports using descriptive features. The study aimed to establish how often these conditions appeared across an entire state population.
2 Study Design
The research used a retrospective case review, meaning the authors examined existing medical and service records. They identified nonduplicated cases seen or treated from 1962 to 1967 across Wisconsin mental-health clinics, hospitals, residential facilities, schools, diagnostic centers, and university hospitals. The reported population included 899,750 children aged 3 to 12. Autism cases were assessed using Kanner criteria, an early clinical definition of autism. The researchers combined records from many services to count affected children across Wisconsin.
3 Findings
The study reported an infantile autism prevalence of about 0.7 per 10,000 children. The available source also reports 280 children aged 3 to 12 who received a DSM-II diagnosis of childhood schizophrenia, an older psychiatric classification. The authors created a broad clinical sample for comparing characteristics across settings and earlier studies. Because identification depended on children reaching participating services, the estimate reflects recognized cases, not necessarily every affected child. The results showed that autism was considered very uncommon in Wisconsin during the study period.