The Behavioral and Developmental Consequences of Corpus Callosal Agenesis and Aicardi Syndrome

Abstract

From the standpoint of developmental psychiatry, studies of the behavioral consequences of agenesis of the corpus callosum (ACC) have to date fallen broadly into two types. First of all, most “behavioral” studies of ACC are accounts of research carried out in controlled laboratory settings, and these include studies involving motor tasks and measures of interhemispheric transfer time, and work in the area of psycholinguistics. These studies, which have been reviewed extensively elsewhere (e.g. Milner and Jeeves, 1979; Lassonde, 1986; Ramaekers, 1991) and must surely be the most informative body of research in the investigation of the psychological concomitants of callosal agenesis, are well represented in the present volume. Secondly, there is a body of research concerning the naturally-occurring behavioral problems of acallosal people (as distinct from behavioral observations from laboratory work). There are two notable examples of this work. Firstly, there is a long history of clinical reporting and research into the purported association between ACC and major mental illness, particularly schizophrenia (Gulman et al., 1982; Hatta et al., 1984). The findings in this area of research are at best inconclusive: it is as yet unclear whether the occurrence of schizophrenia in acallosal individuals is related to the callosal lesion, or to other factors (David, 1989; Njiokiktjien, 1991). The ongoing work into Andermann’s Syndrome (Andermann et al., 1972), where periods of hallucinatory experience — particularly early in adult life — are reported to occur, may shed further light on the specificity of this association. Secondly, in learning-disabled acallosal children, a high frequency of behavior disturbance has been reported, but as yet neither the nature of such behavioral problems nor the extent to which they are related to callosal dysgenesis has been clarified (Roeltgen and Roeltgen, 1989; Njiokiktjien and Ramaekers, 1991).