Sexual dysfunction

Sexual functioning in men and women encompasses behaviours, physiological responses and subjective states of awareness. These phenomena are influenced by personal and relationship histories as well as cultural expectations. A linear sexual response cycle was hypothesized by Masters and Johnson (1966), in which desire precedes initiation of sexual activity, followed by arousal, orgasm and resolution. The psychosexual diagnostic categories of the American Psychiatric Association’s Diagnostic and statistical manual of mental disorders (DSM) (third edition and onwards) are based on this model. In general, a sexual dysfunction is a physiological response and/or state of awareness contrary to these expectations for normative sexual functioning. This chapter will summarize issues relating to sexual dysfunctions including prevalence, risk factors and treatments. Sexual dysfunctions in men Definitions and prevalence Erectile dysfunction (ED) has been defined as ‘the persistent inability to attain and maintain a penile erection adequate for sexual performance’ (NIH Consensus Panel, 1993). Knowledge of the epidemiology of this condition has been facilitated by two large population/community based studies, the National Health and Social Life Survey (NHSLS) (Laumann et al., 1999) and the Massachusetts Male Aging Study (MMAS) (Feldman et al., 1994). In the NHSLS study, the percentage of men reporting difficulties maintaining or achieving an erection ranged from 7% for those aged 18–29 to 18% for those aged 50–59. In the MMAS baseline study, complete ED was reported by less than 10%, moderate by 25% and mild by 17%