Psychodynamic psychotherapy (or psychodynamic therapy) and psychoanalytic psychotherapy (or psychoanalytic therapy) are two categories of psychological therapies. Their main purpose is to reveal the unconscious content of a client's—or patient's—psyche in an effort to alleviate psychic tension, which is inner conflict within the mind that was created in a situation of extreme stress or emotional hardship, often in the state of distress. The terms "psychoanalytic psychotherapy" and "psychodynamic psychotherapy" are often used interchangeably, but a distinction can be made in practice: although psychodynamic psychotherapy largely relies on psychoanalytic theory, it employs substantially shorter treatment periods than traditional psychoanalytical therapies, including psychoanalysis. Studies on the specific practice of psychodynamic psychotherapy suggest that it is evidence-based. Long-term psychoanalytic psychotherapy may offer small but statistically significant benefits over other therapies for complex mental disorders, though findings are limited by study differences and methodology.
Psychodynamic psychotherapy relies more on the interpersonal relationship between the client or patient and the therapist than other forms of depth psychology. They must have a strong relationship built heavily on trust. In terms of approach, this form of therapy uses psychoanalysis in a less intensive style of working, usually once or twice per week, often at the same frequency as many other therapies. The techniques draw on the theories of Sigmund Freud, Melanie Klein, and the object relations theory proponents, including Donald Winnicott, Harry Guntrip, and Wilfred Bion. Some psychodynamic therapists also draw on the work of Carl Jung, Jacques Lacan, and Robert Langs. Psychodynamic therapy has been used in individual psychotherapy, group psychotherapy, family therapy, and to understand and work with institutional and organizational contexts. In psychiatry, it is sometimes used for adjustment disorders and post-traumatic stress disorder (PTSD), but more often for personality disorders.