Perceptual and Motor Skills, 1981, 53, 101-102. @ Perceprual and Motor Skills 1981 REVERSED CEREBRAL ASYMMETRIES AS A POTENTIAL RISK FACTOR I N AUTISM: A RECONSIDERATION EUGENE J. D'ANGELO Children's Hospital Medical Center' Summary.-This paper provides a methodological modification and re- analysis of the data presented by Hier, et d. in 1979 on the presence of unfavorable cerebral asymmetry in autistic patients. In contrast to prior findings, statistical significance was not obtained, suggating that it is premature to assert that such morphologic anomalies may be considered a risk factor in autism. One of the critical features of research on risk for severe psychopathology is the identification of certain variables which, either alone or through inter- action, distinguish a target group from the larger population (Vance, 1977). It is important to select these variables carefully, so that the predictive accuracy for discerning individuals at risk can be maximized. Hier, et al. ( 1979) have undertaken the smdy of morphologic abnormalities in the brains of autistic (n = 16) as compared with mentally retarded (n = 44) and neurological (n = 100) patients. Utilizing computerized tomography (CT), they reported that 57% of their autistic patients evidenced reversed asymmetry, the right parieto-occipital region wider that the left, whereas a similar pattern of cerebral asymmetry was found in only 23% of the mentally retarded and 25% of the neurological patients. Based on these findings, they speculated that reversed asymmetry may be related to impaired language acquisition in autistic children and, in fact, might serve as an identifiable risk factor for the syndrome. While the potential significance of this inference is appreciated, findings from other morphological investigations suggest a sig- - nificant modification to the original research strategy. The present paper accounts for this methodological alteration, providing both reanalysis of data and a statement of the conclusions. In roughly two-thirds of the brains examined, Geschwind and Levitsky ( 1968) observed that the planum of the left temporal lobe was larger than the right. Although speculative, lateral bias in the left posterior region has been proposed as underlying left hemispheric dominance for language (Galaburda, et al., 1978). Based on these findings, Hier, et al. (1979) attempted to test whether there was an increased incidence of reversed cerebral asymmetry in autistic patients. However, instead of comparing frequencies for both left-side and reversed asymmetries among the three patient groups, a 3 X 2 contingency table was apparently derived by combining left-side asymmetry and bisymmetry '300 Longwwd Ave.. Boston, MA 02115.