Most mental health clinicians will be asked to evaluate or treat at least one, if not more, patients with a GID during his or her career. This section is designed to inform mental health care professionals about the diagnosis and treatment of GID in adults, with the primary focus on multimodal treatment. For consideration of etiology and nosological evolution of these conditions the reader is referred to three other publications (Brown 1990a; Denny 1998; Schaefer and Wheeler 1995).

GID is considered clinically distinct from sexual dysfunctions and paraphilias, although some argue for theoretical connections between the conditions. In general, persons with GID include those who experience some incongruence between their anatomic (natal) sex and their psychological experience of themselves as masculine, feminine, or androgynous.

Gender identity conditions encompass a heterogeneous group of syndromes with diverse diagnostic and treatment implications, with transsexualism being the most extreme. Although the term “transsexual” no longer appears as a DSM-IV diagnosis, it continues to have substantial clinical utility spanning many decades. For example, “transsexual” appeared in the title of 19 (27%) of 69 presentations at the 1999 biennial symposium of the Harry Benjamin International Gender Dysphoria Association, the major international organization that deals exclusively with the field of gender identity issues. Therefore, the term “transsexual” and the more inclusive term “transgendered” will appear throughout this chapter with the understanding that only a minority of patients with gender identity conditions (the most extreme cases) would be described as transsexual. Transgendered persons include all those who do not conform to the usual societal expectations of dichotomous male and female gender-role behavior (Bolin 1998). This term is quite broad and necessarily includes a subset of persons meeting criteria for a mental disorder; however, it also includes a much larger group of individuals who do not meet clinical significance criteria for any psychiatric disorder (Denny 1998). Transsexuals and those with other forms of gender identity disorder (gender identity disorder not otherwise specified [NOS]) would therefore be subsets of the transgendered.

Despite three decades of research, the etiology of these disorders remains elusive, determinants of developmental pathways remain controversial, and the complexities of the disorders have consequently created what many now consider to be a unique medical subspecialty dedicated to enhancing knowledge of gender identification and its development (Ihlenfeld et al. 1987; Pauly and Edgerton 1986; Schaefer and Wheeler 1987, 1995; Wheeler and Schaefer 1987).

The estimated prevalence of persons with severe GID, specifically transsexualism, in the adult general population is small. Meyer-Bahlburg (1985) estimated they occur in 1 in 24,000-37,000 men and 1 in 103,000-150,000 women; furthermore, according to figures quoted in DSM-IV (American Psychiatric Association 1994), 1 in 30,000 men and 1 in 100,000 women seek treatments for their transsexual condition. Studies in more homogeneous populations with centralized health care systems reveal that the prevalence is about 1 in 11,900 males over age 15 years and 1 in 30,400 females (Bakker et al. 1993) and that the ratio of males to females presenting for treatment is about 2.5-3 males for each female (Bakker et al. 1993; Landen et al. 1996a, 1996b). Although transsexuals may be more “visible” due to heavy media coverage, it does not appear that the incidence has changed over time (Landen et al. 1996a). However, the prevalence of GID may be underestimated, as it is likely that only a minority of gender-dysphoric persons present for treatment (Brown et al. 1996).

The comprehensive evaluation and treatment of gender disorders is performed primarily by professionals (e.g., psychotherapists, endocrinologists, surgeons) in private practice in a collaborative team approach, as well as in gender identity clinics and special gender programs in some university-based centers. An estimated 35 treatment centers or networks of collaborating professionals currently exist worldwide and can be contacted through the Harry Benjamin International Gender Dysphoria Association [HBIGDA, Executive Director, c/o University of Minnesota, 1300 South 2nd Street, Suite 180, Minneapolis, MN 55454). The “Standards of Care” for treating gender-dysphoric individuals, developed by an international group of experts (Levine et al. 1998) and followed by most responsible professionals in the field, provides a valuable guide for evaluation and treatment. The text of these standards can be obtained at http://www.symposion.com/ijt and should be consulted in addition to this chapter.