Somatization and conversion: distinct or overlapping constructs?

The terms somatization and conversion are used descriptively to define specific diagnostic entities, and phenomenologically to denote pathologic processes that underlie somatic symptom formation. There is a lack of clarity, and even controversy, however, as to whether somatization and conversion should be considered distinct or overlapping constructs, and whether they contribute to the pathogenesis of certain organic diseases or solely to medically unexplained somatic symptoms. This article attempts to resolve some of this confusion by reviewing the origins of the terms somatization and conversion, and describing how their meanings and uses have evolved over the last century. Whereas some psychoanalysts and psychiatrists adopted Stekel's view that somatization involves a psychological process analogous to conversion, others maintained Freud's distinction between the psychoneuroses and the actual neuroses and view somatization as a physiological process. Recent psychoanalytic attempts to understand somatization are based on a modern theory of emotional processing, which is rooted in cognitive science and open to empirical research. Maintaining a conceptual distinction between somatization and conversion has important implications for psychoanalytic therapy.