Prozac and Sexual Desire

To the Editors:

We applaud Frederick Crews’s discussion of the unappreciated problems of antidepressants and the subtle techniques used to enhance their use and sales [NYR, December 6, 2007]. He mentions but does not elaborate on the sexual side effects produced by serotonin-enhancing antidepressants, most commonly the SSRIs such as Prozac, Zoloft, Paxil, Celexa, Luvox, and Lexapro. Today tens of millions of people take these serotonin-enhancing antidepressants. And because Prozac, Zoloft, Paxil, and Celexa are now available in generic forms, their use will only increase.

It is well known that these medications can cause emotional blunting and dysfunction in sexual desire, arousal, and performance in upward of three of every four patients. But we are writing now to add that we believe these side effects have even more serious consequences than currently appreciated, due to their impact on several other related neural mechanisms.^*

Homo sapiens evolved three distinct (yet overlapping) brain systems for courtship, mating, reproduction, and parenting. The sex drive evolved to motivate men and women to initiate sexual contact with a range of partners; romantic attraction evolved to motivate individuals to focus their courtship energy on specific partners, thereby conserving mating time and metabolic energy; and the neural system associated with partner attachment evolved to motivate our forebears to maintain a stable mateship long enough to complete parenting duties.

Studies using functional Magnetic Resonance Imaging (fMRI) indicate that romantic attraction is associated with subcortical dopaminergic pathways—pathways that are suppressed by elevated central serotonin. Hence serotonin-enhancing antidepressants can jeopardize one’s ability to fall in love.

Due to their impact on the sex drive, these medications can also jeopardize other brain/body mechanisms that govern mate assessment, mate choice, pair formation, and partner attachment. For example, female orgasm has many functions. Among them, it aids sperm retention and enables women to discriminate between self-centered as opposed to dedicated partners—partners who might be more likely to help them rear their young. Female orgasm may also help women choose men with better genes, as women are more orgasmic with men who are healthy and symmetrical, markers of good testosterone load. Female orgasm may also enhance feelings of attachment, because it stimulates the release of oxytocin and prolactin. As these drugs impair or eliminate female orgasm, they interfere with delicate biological mechanisms designed to aid mate choice and partner attachment. As these SSRI medications impair male orgasm, they also jeopardize a male’s ability to court, inseminate, and attach to a potential partner.

In short, the sex drive operates in conjunction with many other neural systems that govern desire, mate choice, romantic love, and attachment, perhaps even mechanisms that detect facial attractiveness, immune system compatibility, and other neural systems we unconsciously use to mate, breed, and rear our young. Yet there is, as yet, no research on the complex effects of these serotonin-enhancing drugs—medications that are likely to jeopardize mate choice, romantic love, marriage, and even fertility.

Helen E. Fisher, Ph.D.

Research Professor

Department of Anthropology

Rutgers University

New York City

J. Anderson Thomson Jr., M.D.

Charlottesville, Virginia