2006; Herek and Garnets, 2007). While national probability samples of transgender adults are not available, data from convenience samples similarly show that many, if not most, transgender adults do not report mental health problems (Clements-Nolle et al., 2001; Nuttbrock et al., 2010).
Nonetheless, disparities in mental health do exist among some sexual-minority groups. In a meta-analysis of research on mental health among LGB people published between 1966 and 2005, King and colleagues (2008) examined the prevalence of a number of mental health outcomes. They found that LGB individuals had a 1.5 times higher risk for depression and anxiety disorders over a period of 12 months or a lifetime than heterosexual individuals. Other findings revealed that the risk for suicide attempts over a lifetime among lesbian, gay, and bisexual individuals was more than twice as great as that among heterosexual individuals.
The evidence is not conclusive, however. A study comparing lesbians and their heterosexual sisters as a control group found no difference in the prevalence of mental health problems between the lesbian–heterosexual sister pairs (n = 184 pairs), but found that the lesbians had significantly higher self-esteem than their heterosexual sisters (Rothblum and Factor, 2001). Horowitz and colleagues (2003) examined specific quality-of-life indicators by behaviorally defined sexual orientation categories (heterosexual, homosexual, bisexual since age 18 and within the last 12 months) (n = 11,536). They found that there were no significant differences among heterosexual, homosexual, and bisexual men and women with respect to general happiness, perceived health, or job satisfaction since age 18 or within the last 12 months.
For transgender people, the available studies generally suggest high rates of negative mental health outcomes. Most of these studies, however, are limited by the use of nonprobability samples, and few compare the mental health of transgender people and nontransgender controls. A clinical sample of 31 male-to-females reported significantly more symptoms on the General Severity Index (GSI) of the Brief Symptom Inventory relative to nontransgender men (n = 57). Further analyses of the data indicated clinically significant levels of anxiety and depression, along with increased feelings of self-consciousness and distrust of other people (Derogatis et al., 1978). A clinical sample of 20 female-to-males showed no clinically significant differences on the GSI in comparison with nontransgender females (n = 143); however, scores on subscales of anxiety and interpersonal sensitivity were elevated (Derogatis et al., 1981). There also appear to be mental health differences among lesbian, gay, bisexual, and transgender populations. For instance, in a chart review of 223 lesbians and bisexual women presenting to a mental health clinic, Rogers and colleagues (2003) found that the lesbians were more likely than the bisexual women to present at intake with suicidal ideation, while the bisexual women were more likely to