The borderline personality disorder (BPD) construct originated from the observations of psychoanalytic psychotherapists who were impressed by these patients' demanding search for nurturance, their disregard for the usual boundaries of therapy, and their tendency to regress in unstructured situations. Impelled by the clinical importance of foreseeing such problems and by a new wave of psychotherapeutic optimism, empirical work was initiated to better define this disorder. Early research raised the question of whether such patients had an atypical form of mood disorder rather than an atypical form of schizophrenia, as had been thought, and more importantly led to inclusion of BPD in DSM-III.