Symptomatic loss of libido is a common problem in the United States. In a national survey conducted in 1994, 33 percent of women and 17 percent of men reported sexual disinterest.¹ In another survey, one third of women 18 to 59 years of age reported feeling a lack of sexual desire within the previous year.² Patients with major depressive disorder or bipolar disorder have an even higher prevalence of sexual dysfunction, including lowered libido, than the general population.³

In one study it was found that more than 70 percent of depressed patients had a loss of sexual interest when not taking medication, and they reported that the severity of this loss of interest was worse than the other symptoms of depression.⁴ In this same study, libido declined with increasing severity of psychologic illness. The complex association between depression and lowered libido is further illustrated in a case control study in which increased lifetime prevalence rates of affective disorder were found among patients with inhibited sexual desire.⁵

Regardless of the cause-and-effect relationship, depression and decreased libido are associated, and the treatment of one condition may improve the other. This article focuses on decreased libido associated with depression, the effects of treatment of depression on libido, and the effects of changes in libido and sexual functioning on compliance.

Discussing Libido

Patients have difficulty discussing sexual dysfunction (decreased libido, erectile dysfunction and anorgasmia) and acknowledging decreased libido may be particularly difficult. Patients under-report sexual problems caused by medications.^6,7 They may acknowledge a decline in libido only if their partner complains. Even when a declining interest in sex is recognized, it may be rationalized on the basis of social values and practices, especially among aging women.⁸ Discovery of sexual problems is further limited by the frequent failure of physicians to ask about such problems.⁹ The latter point is critical: in one study it was found that patients taking selective serotonin reuptake inhibitors (SSRIs) were four times more likely to reveal sexual dysfunction if asked directly by their physician.⁷

It is important to get baseline information about sexual dysfunction, including lowered libido, to accurately assess the effects of treatment. The authors have found that placing libidinal effects in the context of the patient's general interests and activities avoids suggestion and excessive preoccupation, but allows adequate assessment before and after treatment is initiated.

Other Issues Affecting Libido

Patients whose depression improves with treatment but who continue to experience a lowered libido should be asked about their use of other medications. Several antipsychotic agents, including haloperidol (Haldol), thioridazine (Mellaril) and risperidone (Risperdal) can decrease libido.^9,10 Cimetidine (Tagamet), in contrast to ranitadine (Zantac), has been found to lower libido and cause erectile dysfunction.¹¹

Women in their late reproductive years who take oral contraceptives and postmenopausal women who are given estrogen replacement therapy may experience an improvement of depressive symptoms but a lowering of libido.¹² Libido lowering is attributed to estrogen-induced deficiency of free testosterone.^12,13 Testosterone testing and supplementation should be considered in women who experience a decline in libido after starting estrogen therapy. ¹⁴ Testosterone testing should also be considered in men who have a gradual loss of libido and no improvement despite adequate treatment for depression.¹⁵

It is important to assess the patient for psychologic and interpersonal factors that commonly affect depression and sexual desire. These factors include stressful life events (loss of job or family trauma), life milestones (children leaving home) and ongoing relationship problems.¹⁶

Alcohol and narcotics are known to decrease libido, arousal and orgasm.¹⁷ Because the use of alcohol and other drugs is more common in patients with psychologic disorders, alcohol and drug abuse should be considered when investigating libido problems in patients with depression.

Lowered Libido After Treatment

Consistent evidence shows that, with the exception of bupropion (Wellbutrin), trazodone (Desyrel) and nefazodone (Serzone), antidepressant medications may cause a decline in libido or sexual functioning despite improvement of depression.¹⁸ Up to one half of patients surveyed before and after starting therapy with the SSRIs fluoxetine (Prozac), paroxetine (Paxil), fluvoxamine (Luvox), citalopram (Celexa) and sertraline (Zoloft) reported a decline in libido with medication use.⁷ SSRIs also cause other sexual dysfunction that can affect libido and compliance.^19,20

In a double-blind clinical trial of treatment with imipramine (Tofranil), phenelzine (Nardil) or placebo, it was found that 30 to 40 percent of patients taking either antidepressant reported a decline in sexual desire, while 6 percent of those taking placebo experienced the same effect.²¹ Although the use of monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants to treat depression is on the decline, tricyclic agents are increasingly being prescribed for control of pain. When tricyclics are prescribed for pain, it is not uncommon for them to be used in conjunction with SSRIs. SSRIs increase serum levels of tricyclics, so this combination may affect libido more than either alone. Table 1 summarizes the effects of various antidepressants and antipsychotics on libido.

MANAGEMENT

When libido remains low after depression has been treated, the other issues discussed above should be considered. When decreased libido begins or worsens after a patient starts taking antidepressant medications, it is important to address the problem without compromising the treatment of the depression. Failure to deal with the sexual problem may result in treatment noncompliance.²²

Several options exist for managing medication-induced sexual dysfunction (Figure 1). Decreasing the dosage of the antidepressant may improve libido while maintaining adequate treatment of depression. In one study, 73 percent of patients whose SSRI dosage was halved reported improved sexual function while antidepressant effectiveness continued.⁷ This dosage effect has also been found for SSRIs and imipramine in other studies.^21,23,24 The only evidence about drug holidays comes from a small, open study in which findings suggest that one- to two-day holidays from the shorter half-life SSRIs (i.e., sertraline, paroxetine) may be helpful. This effect did not apply to fluoxetine.²⁵

If a reduction in the antidepressant dosage does not maintain adequate treatment of depression, other options are to add a medication and change the medication. In studies comparing bupropion with sertraline and placebo, patients treated with bupropion experienced improvement in libido.²⁶ There is good evidence that treatment with bupropion raises libido above predepression levels.²⁷ In less rigorous studies, improvement of libido with a change to bupropion or the addition of bupropion to existing medications was found.^28,29 Patients who switched from sertraline to nefazodone in a double-blind clinical trial reported that their libido returned to baseline levels.³⁰

PSYCHIATRIC THERAPY FOR DISORDERS OF SEXUAL DESIRE

Psychotherapy has variable effects for depression-related problems of sexual desire.³¹ Better outcomes are associated with the absence of life-long or global desire disorders and with strong relationships.¹⁶ In a review of published studies regarding psychotherapy for sexual dysfunction, it was found that in nearly 80 percent of the published reports the research was of poor quality and that no treatment was consistently useful.³²

Final Comment

Decreased libido affects many patients but disproportionately affects patients with depression. There is evidence that the decline in libido is related to the depth of depression. It is important to get baseline information regarding libido and sexual function before initiating treatment for depression. It is also important to assess patients' libido and sexual functioning after starting antidepressant therapy, as patients may be reluctant to report difficulties.

If treating the depression does not improve libido, other causes of sexual dysfunction should be considered, such as hormone deficiencies, chronic disease, drug and alcohol abuse, or use of other medications. Evidence supports several treatment options in patients who experience sexual dysfunction or decreased libido as a consequence of anti-depressant use. These include decreasing the dosage of an SSRI or tricyclic antidepressant, instigating medication holidays, adding or switching to bupropion, and using nefazodone as an alternative agent. Cause and effect may not be clear, but addressing sexual desire when treating depression may improve compliance and overall outcome.