Psychoanalysis and psychoanalytic psychotherapy have been shown to be effective forms of treatment for a wide range of difficulties. Studies have concluded that people who have had psychoanalytic psychotherapy or psychoanalysis maintain the changes they have achieved through the therapy over time. This is thought to be in part because they have developed cpaccities to understand themselves better and to analyze new difficulties that arise. Benefits include improvement in relationships, work and self-esteem.
Evidence for effectiveness is considerable. In 2008 the American Medical Association published a review of a large number of studies. The review concluded that long-term psychodynamic psychotherapy engendered more long lasting personality change in persons with complex disorders than short-term, non-psychodynamic therapies.
In 2009 another review of a large number of psychotherapy studies conducted from 1970 to 2007 was published in the Harvard Review of Psychiatry. This review concluded that empirical evidence showed that long-term psychoanalytic psychotherapy and psychoanalysis produced significant improvement in symptoms and personality. Moreover, the effects of this long-term treatment were maintained in post-treatment years.
Additionally, neuroscientists studying the brain have underscored the significance of unconscious thought and the beneficial impact of the therapeutic relationship on brain function.***
The following links contain information and empirical research supporting the efficacy of psychoanalytic psychotherapy and psychoanalysis:
http://www.apsa.org/Research/Empirical_Studies_in_Psychoanalysis.aspx
http://www.ipa.org.uk/default.aspx?page=34