There can be other factors such as problematic substance use or dependency or behavioral addictions. Therapists in this area can become disheartened by lack of initial progress, or by apparent progress that then leads to setbacks. Clients may be perceived as negative, rejecting, demanding, aggressive or manipulative. This has been looked at in terms of both therapist and client; in terms of social skills, coping efforts, defense mechanisms, or deliberate strategies; and in terms of moral judgments or the need to consider underlying motivations for specific behaviors or conflicts. The vulnerabilities of a client, and indeed a therapist, may become lost behind actual or apparent strength and resilience. It is commonly stated that there is always a need to maintain appropriate professional personal boundaries, while allowing for emotional expression and therapeutic relationships. However, there can be difficulty acknowledging the different worlds and views that both the client and therapist may live with. A therapist may assume that the kinds of relationships and ways of interacting that make them feel safe and comfortable have the same effect on clients. As an example of one extreme, people who may have been exposed to hostility, deceptiveness, rejection, aggression or abuse in their lives, may in some cases be made confused, intimidated or suspicious by presentations of warmth, intimacy or positivity. On the other hand, reassurance, openness and clear communication are usually helpful and needed.
James Cowles Prichard advanced a similar concept he called moral insanity, which would be used to diagnose patients for some decades. Moral in this sense referred to affect (emotion or mood) rather than ethics, but it was arguably based in part on religious, social and moral beliefs, with a pessimism about medical intervention so social control should take precedence. These categories were much different and broader than later definitions of personality disorder, while also being developed by some into a more specific meaning of moral degeneracy akin to later ideas about psychopaths. Separately, Richard von Krafft-Ebing popularized the terms sadism and masochism, as well as homosexuality, as psychiatric issues. The German psychiatrist Koch sought to make the moral insanity concept more scientific, and in 1891 suggested the phrase psychopathic inferiority, theorized to be a congenital disorder. This referred to continual and rigid patterns of misconduct or dysfunction in the absence of apparent "mental retardation" or illness, supposedly without a moral judgment. Described as deeply rooted in his Christian faith, his work established the concept of personality disorder as used today. 20th century
In the early 20th century, another German psychiatrist, Emil Kraepelin, included a chapter on psychopathic inferiority in his influential work on clinical psychiatry for students and physicians. He suggested six types – excitable, unstable, eccentric, liar, swindler and quarrelsome. The categories were essentially defined by the most disordered criminal offenders observed, distinguished between criminals by impulse, professional criminals, and morbid vagabonds who wandered through life.