Complex sentence: The DSM-5 defines the main features of BPD as a "pervasive pattern" of "instability in interpersonal relationships, self image and affects, and markedly impulsive behavior" and specifies the disorder must meet 5 of 9 criteria for diagnosis.
Split into simpler sentences: The DSM-5 defines the main features of BPD as a pervasive pattern of instability in interpersonal relationships, self image, and affects, as well as markedly impulsive behavior. It specifies that the disorder must meet 5 of 9 criteria for diagnosis.