Scientists have shown that levels of serotonin in the brain, measured before treatment, are linked to the likelihood of experiencing sexual dysfunction while on SSRI antidepressants.
Although there is no current method to foresee which depressed patients will develop sexual side effects from medication, this finding could help clinicians select drugs that preserve sexual function during treatment. The study was presented at the ECNP conference in Amsterdam.
Sexual problems are a frequent issue in depression. SSRIs can improve overall mood but often come with side effects such as reduced libido, erection difficulties, and trouble achieving orgasm. These problems affect up to 70 % of people taking medications like Prozac or escitalopram, sometimes leading to discontinued therapy.
The research team in Copenhagen examined 90 individuals diagnosed with depression. They used the Loudness Dependence of Auditory Evoked Potentials (LDAEP) test—a non‑invasive EEG procedure that records how the brain responds to sounds—to estimate brain serotonin activity; a lower LDAEP score indicates higher serotonin levels.
Participants then entered an eight‑week SSRI regimen while researchers monitored any emerging sexual issues. This allowed comparison between initial LDAEP readings and later side‑effect profiles.
Lead investigator Dr. Kristian Jensen, from Copenhagen University Hospital, explained, “Our data show that patients with higher pre‑treatment serotonin activity are significantly more likely to develop sexual side effects by week eight, particularly orgasmic problems.”
Using LDAEP scores together with baseline information on depression‑related sexual concerns, the team could predict orgasmic capability with 87 % accuracy. A larger, more balanced study is needed to refine predictions for erectile dysfunction.
“Patients currently discover sexual side effects only after starting medication,” Jensen added. “If we can measure serotonin activity at the outset, we might anticipate and mitigate these problems, improving adherence and quality of life.”
Researcher Professor Eric Ruhe, a specialist in difficult‑to‑treat depression, noted, “This study presents a clever, easy‑to‑administer test that could forecast sexual side effects before treatment begins.” He encouraged further work to identify alternatives for patients prone to SSRI‑related dysfunction.
While the current research focuses on medication‑induced sexual dysfunction, the team plans a 600‑patient study to explore how serotonin and sex hormone levels jointly affect sexual function in depression and during treatment.
“The LDAEP is elegant—sounds played at varying volumes while EEG records brain activity,” Jensen said. “It takes about 30 minutes, is non‑invasive, and, if validated, could become widely available.”