Sexual medicine consultant Professor Alan Riley covers both sexes in his guide to this heartsink symptom
The key diagnostic features of loss of sexual desire are:
• Diminished or absent feelings of sexual desire or interest
• Absent sexual fantasies and daydreams
• Lack of sexual feelings triggered by sexual stimulation (such as foreplay)
• Diminished or absent motivation for attempting to experience sexual stimulation, leading to sexual arousal.
Loss of sexual desire can exist as an isolated problem, but frequently it co-exists with other sexual difficulties, especially in women where the triad – loss of sexual desire, arousal dysfunction and orgasmic disorder is particularly prevalent.
Prevalence
It is difficult to be precise about the prevalence of this problem, as different definitions have been used in different studies.
Population studies have generally identified men and women with loss of sexual desire but have not quantified the proportion of these people who are actually troubled by the loss.
In women, loss of sexual desire is the most common sexual symptom, occurring in up to 25% of premenopausal and about 50% of postmenopausal women. The corresponding figure in men across the age range 40 to 80 years is up to 28%.
Possible causes
Of all sexual difficulties, loss of sexual desire is the least well understood, the most difficult to treat and has the least successful therapeutic outcome.
The aetiology of loss of sexual desire is multifactorial and complex, involving neuro-endocrine, psycho-social and behavioural factors. Frequently, various aetiological factors co-exist. Common factors are given in the box (right).
Evaluation
Try to uncover exactly what the patient means by their complaint of loss of sexual desire. This can be harder than it seems because patients may lack understanding of the different elements of the sexual response (sexual desire, arousal, orgasm) to be able to clearly express their symptom.
Some patients say they have lost sexual desire when in reality they experience desire but gain no satisfaction from sexual activity. They may go on to lose sexual desire, because gaining satisfaction from a sexual behaviour is an important reinforcer. For example, if a person never – or rarely – gains satisfaction from making love with their regular partner, there is no reinforcement to make the person continue to make love to that partner, and loss of sexual desire occurs.
A useful way of gauging sexual satisfaction is how close what we get out of sex comes to what we expect to get out of it. Many patients, particularly women, who present with loss of sexual desire have unrealistic expectations and so are rarely satisfied. It is important to assess the patient's level and their criteria for sexual satisfaction during the preliminary evaluation.
During the first evaluation it is important to ascertain the reference point against which the patient judges themselves as having lost sexual desire. They may remember a time when they experienced more sexual desire. If so, can the patient recall the time point at which the change occurred and what was happening in their life at that point?
A decrease in sexual desire can be expected with increasing age and with duration of relationship.
Some patients judge their loss of sexual desire against the level of desire that the patient expects and this is often unrealistically high. Alternatively, the patient may judge their loss of desire against the partner's desire level – which may have been constant or increased – suggesting a discrepancy in sexual desire within the relationship.
There are two main patterns of sexual desire – spontaneous or responsive. The latter is where the person never or only rarely experiences spontaneous desire, but develops the feelings of desire when sexually stimulated.
This pattern appears to be more common in women than in men, and can lead to relationship conflict because the person, lacking spontaneous desire, rarely initiates sexual interaction. People whose pattern of sexual desire is responsive sometimes think they are abnormal and present with loss of sexual desire.
It is important to find out whether the loss of sexual desire is global (affecting all sexual behaviour) or situational. The most frequent situational loss of sexual desire is where the patient has lost desire to have sexual interaction with his or her regular partner, but still has desire for other sexual activities such as masturbation or sex with another partner. Patients with situational loss of sexual desire have intact biological drive mechanisms and so do not generally need endocrine investigations.
Global loss of sexual desire raises the possibility of an organic aetiology, but does not exclude depression, or psychological or behavioural causes.
Investigations
Routine endocrinologic investigation in pre-menopausal women presenting with global loss of sexual desire is controversial. Concomitant menstrual disturbance or infertility increase the likelihood of endocrinopathy being an aetiological factor, especially if the features listed in the box (above left) are present.
Laboratory investigation may include total and free testosterone, prolactin, sex hormone binding globulin, 17 oestradiol B, dehydroepiandrosterone sulphate and TFTs. In premenopausal women, the blood sample for these investigations should be taken on the fifth or sixth day of the menstrual cycle.
Testosterone deficiency in women can occur at any age, but is more common after premature menopause, bilateral oophorectomy or chemotherapy.
Management
Before addressing the loss of sexual desire, any organic diseases and depression identified should be treated. Remember that loss of sexual desire can be a presenting symptom of depression and can be helped by a low-dose antidepressant.
Of course all antidepressants carry the risk of impairing sexual functioning.
Specific medical treatments have only very limited application in the management of loss of sexual desire. In men, hypogonadism should be treated by testosterone replacement. Although testosterone treatment has been used to enhance sexual drive in women since
the 1940s, no preparation is currently licensed for this purpose. The only testosterone therapy licensed for women is Intrinsa, which is only licensed for use in women who have testosterone deficiency following bilateral oophorectomy or chemotherapy.
Although oestrogen may not have a direct effect on sexual desire, many postmenopausal women notice an improvement in their sexual desire during oestrogen replacement therapy. This is probably a secondary effect resulting from enhanced mood, improved sleep patterns, amelioration of the discomfort of vaginal dryness and restoration of feelings of femininity. Tibolone, by virtue of its androgenic property, is especially helpful
in restoring sexual desire in some postmenopausal women.
Consider early referral to an accredited sex and relationship therapist or to a member of the Institute of Psychosexual Medicine (www.imp.org.uk), where all members are medical practitioners.
Even patients in whom a possible organic aetiology for their loss of sexual desire is identified will generally benefit from sex and relationship therapy, because so often the cause of the problem is multifactorial.
Some people find appropriate books useful. Two books that may help patients are listed in ‘Patient resources' below.
Professor Alan Riley has specialised in sexual medicine for more than 40 years and was professor of sexual medicine at the University of Central Lancashire until his recent retirement
Loss of sexual desire Table 1 Table 2
