In healthy men, testosterone production remains relatively stable until the fifth decade and then decreases slowly over the remainder of the man’s life at a rate of about 1.0% per year¹⁵. It is probably mainly a result of testicular ageing, although a rise in sex hormone-binding globulin (SHBG) and testosterone-binding, a relative failure of the hypothalamo-pituitary axis to drive the testes, and a decline in the level of sensitivity of testosterone receptors in the brain also contribute. The decline in circulating testosterone occurring in older men is responsible for the decrease in desire, but not erectile function, although clinically it may be difficult to distinguish reliably between the two complaints¹⁶.

In women, the most prominent biochemical markers of sexual maturation and senescence are the age-related changes in the level of oestrogen and testosterone. The structural integrity of the female genitalia is predominantly maintained by oestrogen. Vaginal dryness and atrophy, dyspareunia and urinary tract symptoms suggest a lack of oestrogen which is more prevalent following the menopause¹⁷.

In healthy women testosterone levels decline markedly until the fourth decade with stable levels during the menopause transition. Testosterone levels then increase slowly over the rest of the life span¹⁸.

Master and Johnson’s¹⁹ landmark research in the physiology of sexual responses have provided important information regarding sexuality and ageing, although their sample size was small. In both sexes, as one ages, the speed and intensity of the various vasocon-gestive responses to sexual stimulation tend to be reduced. In men all responses are slower and less intense from nipple and penile erection to rectal orgasmic contractions. An erection takes longer to develop and usually requires more direct tactile stimulation. The period of sustaining an erection gets shorter.

Ejaculation becomes less powerful with fewer contractions and seminal fluid volume is reduced. The point of ejaculatory inevitability becomes more difficult to recognize. Resolution following orgasm is rapid, with loss of erection occurring within seconds and the refractory period is markedly longer in comparison to younger men, sometimes extending to more than a day. In women the responses parallel those of the male. Increased time is required to become sexually aroused and vaginal lubrication is slower and less marked. Orgasms tend to be less intense and there is an increased need for stimulation to become orgasmic. There is no change in the ability to have orgasms, although multiple orgasms are less likely to occur. Resolution is more rapid.

Many older people are unaware of the normal age-related changes in sexual response that accompany ageing and are perplexed or put off by changes in their own or their partner’s sexual response. If not appreciated, these changes are easily misinterpreted as sexual dysfunction. Explicit information about changes in sexual physiology with ageing can help eliminate false expectations and can permit modification in longstanding sexual practices that may have become counterproductive. Couples can be advised, for example, not to delay sexual exchange until late at night when tiredness or sleepiness may be great but, rather, to schedule their sexual encounters at a time of greater energy and alertness.

Similarly, increased manual or oral stimulation of the penis may be necessary to achieve an adequate erection for intercourse and may augment the effects of pharmacological therapy²⁰. The female partner is often unaware of this important physiological change in her partner, and may misattribute his lack of erection to sexual disinterest or her loss of sexual attractiveness to her partner²¹.

Many older couples indicate they would enjoy greater sexual experimentation in their relationship, even though many have minimal experience of foreplay or non-intercourse forms of sexual stimulation²². While the overall decline of the sexual responses may seem gloomy and unpleasant, this process tends to develop extremely gradually, allowing an individual or a couple to adjust to a less intense, but not necessarily less enjoyable form of sexual activity.

One of the most frequent reasons given by older people for stopping sexual activity is the onset of illness; this may operate through a number of different mechanisms. Physical illness may generate unfounded anxieties about the risks of sexual activity (as in heart disease or stroke); it may make intercourse difficult, exhausting or painful (as in respiratory disease, arthritis and (sexually transmitted) infection); or it may impair responsiveness of the sexual organs (as in diabetes mellitus or peripheral vascular disease).

Illness may further undermine self-confidence and the feeling of attractiveness (as in mutilating operations such as mastectomy or colostomy), and it may have a direct effect in reducing sexual desire (as in depression, chronic renal or hepatic failure, and Parkinson’s disease). Older people in general are more likely to suffer from a variety of chronic diseases which may impact on their sexual function²³. They also commonly undergo surgery, which may influence sexual function, either because of psychological sequelae or as a result of organic damage¹⁶.

If illness has reduced the capacity to respond to sexual stimulation, and this is something a couple cannot understand or discuss, then they cannot resolve this difficulty. In a relationship where the assumption was that the man always takes the active role in sexual exchange, his partner may be quite unused to stroking his penis as part of their preparation for intercourse, and may find it difficult to help him if this is what he requires. Similarly, if there is a transition from an equal partnership to one of caregiver and patient due to severe illness the latter may lose the self-esteem which reassures him that he is still contributing to the relationship; or the caring partner may think it unkind and selfish to make demands on the sexual responsiveness of the one who is ill. Particularly if there is a lack of communication around sexual issues, sexual relationship changes may never be adequately worked out. But even simple actions can have far-reaching effects, such as when a couple decide they should sleep apart so as to give the ill partner a better night’s rest, resulting in a potential reduction of closeness and intimacy.

Generally, the complaints in older people differ little from those of younger people who seek help for their sexual problems; they may have psychological or physical origins, or both. Fear of poor performance, lack of, or diminished sexual desire, difficulty becoming sexually aroused either physically or psychologically, difficulty maintaining an erection, difficulty achieving orgasm, and pain or discomfort with sexual activity, especially during intercourse, as well as a lack of opportunities for sexual encounters are among the most common of the complaints that older people present with^21,29,30.