Etiological relevance of comparisons of high-risk and low-risk groups

The prospective study of groups at high risk for pathology is viewed as an increasingly important strategy in research on the etiology and possible prevention of a wide range of disorders. Yet, relatively little attention has been paid to proper and improper etiological interpretations of results based on studies of such groups. The comparison of groups at high risk and low risk for pathology, prior to the development of relevant disturbances in the subjects, cannot provide evidence that a given factor or a characteristic of the groups does or does not contribute to the etiology of the disturbances which will develop in the subjects. For the data to become etiologically relevant, they must be studied as possible antecedents to disturbances identified by following up the subjects. On the other hand, comparisons of high-risk versus low-risk groups are most appropriately interpreted as reflecting the characteristics, correlates and/or consequences of the risk criterion, and such comparisons may thus contribute to better understanding of the true meaning and ramifications of the risk criterion. Considerable caution must be exercised both by high-risk researchers and by observers of high-risk studies in interpreting the significance of results of these studies.