Brain test predicts ability to reach orgasm, but only in patients taking antidepressants

Researchers have found that the ability to get an erection or have an orgasm is linked to serotonin levels in the brain, but this relationship only applies to depressed patients taking SSRI antidepressants.

Currently, there is no test to determine who might experience sexual problems during treatment for depression, but this finding could help depressed patients choose antidepressants that allow them to maintain or regain an active sex life when treated with antidepressants. This work was presented at the ECNP conference in Amsterdam.

Sexual dysfunction is a common symptom of depression. SSRI antidepressants can help relieve sexual dysfunction by improving mood, but at the same time, SSRIs themselves are often associated with sexual side effects.

Unfortunately, there is no way to predict these side effects in advance. Difficulty achieving orgasm is a common side effect, as is decreased desire and difficulty maintaining an erection. These side effects can affect up to 70% of patients taking SSRI medications, such as Prozac and escitalopram. These effects can be distressing and often lead people to stop treatment.

The Copenhagen-based researchers studied 90 people who had been diagnosed with depression. They measured brain serotonin activity using a special EEG test called LDAEP (Loudness Dependence of Auditory Evoked Potentials), which is like a hearing test that reveals how your brain processes sound; Perhaps surprisingly, this also tells us about serotonin levels in the brain: the lower the LDAEP, the higher the serotonin activity.

The patients then began an 8-week course of SSRI antidepressants, with researchers carefully monitoring any sexual side effects that developed. This allowed the researchers to see if they could predict who would have sexual problems based on their LDAEP measurement before treatment.

Lead researcher Dr Kristian Jensen (from Copenhagen University Hospital) said: “We found that people with higher serotonergic activity before starting treatment were much more likely to develop sexual side effects at the end of the eight-week antidepressant treatment, particularly difficulty achieving orgasm.

“Using this non-invasive brain measurement combined with information about sexual problems related to their depression, we were able to predict the ability to achieve orgasm with an accuracy of 87%. We need a larger study, with more men, to get an accurate number on erectile dysfunction.”

He continued: “Currently, patients only discover sexual side effects after starting antidepressant treatment. Measuring serotonin activity via the LDAEP test at the start of antidepressant treatment allows us to predict the likelihood of later sexual problems due to SSRIs.

“If confirmed, our findings could enable a more precise approach to treating depression, helping doctors select medications to minimize sexual side effects in patients most likely to develop SSRI-related problems. This could help with treatment adherence and overall quality of life and generally provide better treatment options for depression.

“Our findings appear to apply only to drug-induced sexual problems, so it is not a general test for sexual difficulties. However, we are now looking to refine this. We have an ongoing study of 600 patients that will examine how serotonin levels combined with sex hormone levels affect sexual function during depression and medication use.”

Commenting, Professor Eric Ruhe, Professor of Difficult-to-Treat Depression at Radboudumc, Nijmegen, Netherlands, said: “This is a very interesting study in which researchers innovatively use an easy-to-administer test to predict the risk of sexual dysfunction after starting (use of) an antidepressant.

“When replicated, this type of test could reliably help to know in advance whether or not a patient will have sexual adverse effects. As many patients experience sexual dysfunction after starting treatment with SSRI antidepressants (such as escitalopram), the most important clinical application will be to predict that sexual dysfunction will not occur, particularly in patients who worry of this side effect and are hesitant to start treatment. “

“I also encourage researchers to expand their efforts to develop a tool that can advise which medication to take instead, without relying solely on current pharmacological considerations.”

Professor Ruhe was not involved in this work; this is an independent comment.

This work is currently under peer review. The researchers note that the study subjects were relatively young (average age 27) and predominantly (73%) women. They are now aiming to replicate the study on a much larger group of 600 patients.

Dr Jensen said: “The LDAEP itself is quite elegant: we play sounds at different volumes through headphones while measuring brain waves. It takes approximately 30 minutes and is non-invasive. It is not generally available at the moment, but that could change if this test meets expectations.”