Biological foundations of “specific developmental disorders”;: Methods, findings and future directions

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Abstract
Common among childhood disorders are those that involve relatively specific deficits in attention, activity level, learning, language, or perceptual‐motor functions. These disorders, referred to in this paper as specific developmental disorders (SDD), are of ten presumed to have a biological‐genetic basis. However, the actual grounds for this presumption are frequently taken for granted. The present paper critically examined the evidence favoring the biological hypothesis in order to evaluate this presumption. This review of the several sources of supportive evidence—including sex and familial biases, pre‐ and perinatal complications, minor physical anomalies, medication response, and infrabehavioral signs—suggests that the presumption of biological antecedents to SDD is warranted. However, it is important to recognize that this presumption represents only a hypothesis, and that careful scrutiny of the methods on which supportive evidence is based reveals a number of common shortcomings. Due to these shortcomings, findings of potential etiological significance have been inconsistent and of limited value for specifying correlates or subtypes of these disorders as well as for predicting response to treatment and prognosis in individual children. Further investigation of the biological hypothesis is clearly worthwhile but will require more sophisticated methods of sample selection, more attention to the measurement characteristics of the presumptive indices, and a wider scope of inquiry.