Background: Reports indicate that catatonia often occurs in autism. The association lacks a conceptual basis. Modern classificatory schemes define autism and catatonia separately and are not conducive to study areas of overlap. The exploration of the relation between autism and catatonia may be important because autism is increasingly recognized but effective treatments are lacking.Catatonia, on the other hand, is thought to be treatable, but is poorly recognized.
Material/Methods: The literature on autism and catatonia are reviewed to identify areas of overlap. A hypothesis
is formulated that, in some cases, autism may the early expression of catatonia.
Results: Several areas of overlap between autism and catatonia are found. Catatonic symptoms are common in autism. Effects of anti-catatonic treatments on autistic symptoms are unknown. Abnormal gamma-aminobutyric acid (GABA) function has been implicated in both disorders. Neuroimaging studies show small cerebellar structures in both disorders. There is genetic evidence that susceptibility genes for autism and catatonia are located on the long arm of chromosome 15. Differences between autism and catatonia of age-of-onset, symptoms, and illness course, do not exclude a common genetic etiology.
Conclusions: Focused research is needed to further evaluate the phenomenological, biological, and genetic overlap between autism and catatonia and to test the hypothesis that a subgroup of autism is early-onset catatonia.

Keywords: Adolescent, Age of Onset, Autistic Disorder - diagnosis, Catatonia - diagnosis, Catatonia - etiology, Cerebellum - metabolism, Child, Prader-Willi Syndrome - diagnosis, Psychotic Disorders - diagnosis, gamma-Aminobutyric Acid - metabolism, Adolescent, Age of Onset, Autistic Disorder - diagnosis, Catatonia - etiology, Cerebellum - metabolism, Child, Prader-Willi Syndrome - diagnosis, Psychotic Disorders - diagnosis, gamma-Aminobutyric Acid - metabolism