The nonpsychotic schizophrenia-like syndrome that has come to be called schizotypal personality disorder (SPD) existed before DSM-IV (American Psychiatric Association, 1993), before Meehl's classic presidential address on schizotaxia, schizotypy, and schizophrenia to the American Psychological Association in 1962 (Meehl, 1962), before the original Diagnostic and Statistical Manual of the American Psychiatric Association (1952). This chapter attempts to give the reader a sense of the origins of the SPD diagnosis, the course of its development as a nosological entity, and where it stands today. The role of family-genetic studies in defining SPD and its relationship to schizophrenia is emphasized throughout.

The chapter begins with a brief historical overview of early descriptions of nonpsychotic schizophrenia-like syndromes and notes that familiality has been associated with these syndromes since their initial description. Next, more recent empirical family-genetic approaches that have led to the development of the current diagnostic criteria for SPD in DSM-IV are reviewed. The chapter concludes with the results from a recent analysis of the present diagnostic criteria as an example of one approach to the continuing development of reliable and valid descriptors of SPD and suggests other contributions that future family and genetic studies may offer.

Historical background

Schizophrenia and nonpsychotic schizophrenia-like syndromes

The history of SPD begins with the history of schizophrenia. Eugen Bleuler, in his initial description of schizophrenic illness, broadened Kraepelin's construct of dementia praecox to include what Bleuler termed latent schizophrenia (latente schizophrenic; Bleuler, 1911), a less severe, nonpsychotic presentation of schizophrenia.