One of the most important questions of our previous common volumes about affective, schizoaffective, and schizophrenic disorders was the question of what connects and what separates psychotic disorders (Marneros and Tsuang, Schizo affective Psychoses, Springer-Verlag, 1986; Marneros and Tsuang Affective and Schizoaffective Disorders, Springer-Verlag, 1990; Marneros, Andreasen, and Tsuang, Negative and Positive Schizophrenia, Springer-Verlag 1993). The boundaries between various psychotic d...