Brain test predicts ability to achieve orgasm—but only in patients taking antidepressants

Researchers have discovered that the ability to have an erection or to orgasm is related to the levels of serotonin in the brain, but this relation only applies to depressed patients taking SSRI antidepressants.

At the moment, there is no test for who might experience sexual problems during treatment for depression, but this discovery may help depressed patients to choose antidepressants which 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 sexual dysfunction by improving mood, but at the same time, SSRIs themselves are often associated with sexual side effects.

Unfortunately, there’s no way of predicting these side effects in advance. Difficulty reaching orgasm is a common side effect, as are reduced 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, often leading to people stopping 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 started an 8-week course of SSRI antidepressants, with the researchers carefully tracking any sexual side effects that developed. This allowed the researchers to see if they could predict who would have sexual problems based on their pretreatment LDAEP measurement.

Lead researcher Dr. Kristian Jensen (from Copenhagen University Hospital) said, “We discovered that people with higher serotonin activity before treatment started were much more likely to develop sexual side effects by the end of the eight-week antidepressant course, especially difficulty reaching orgasm.

“Using this non-invasive brain measure combined with information about sexual problems related to their depression, we could predict the ability to reach orgasm with 87% accuracy. We need a bigger study, with more men, to get an accurate figure for erectile dysfunction”.

He continued, “Currently, patients only discover sexual side effects after they’ve already started antidepressant medication. Measuring serotonin activity via the LDAEP test at the start of the course of antidepressants allows us to predict the likelihood of later sexual problems due to the SSRI.

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

“Our findings seem only to apply to medication-induced sexual problems, so it’s not a general test for sexual difficulties. However, we are now looking to refine this. We have a 600-patient study underway which will look at how serotonin levels combined with sex hormone levels affect sexual function during depression and medication”.

Commenting, Professor Eric Ruhe, Professor of Difficult-to-Treat Depression at Radboudumc, Nijmegen, the Netherlands, said, “This is a very interesting study where the researchers innovatively use an easy-to-administer test to predict the chance of sexual dysfunction after the start of antidepressant [use].

“When replicated, this type of test might reliably help to know beforehand whether a patient will have sexual adverse effects or not. As many patients experience sexual dysfunction after the start of SSRI antidepressants (like escitalopram), the most important clinical application will be to predict that sexual dysfunction will not occur, especially in patients who worry about that adverse effect and are hesitant to initiate treatment.”

“I also encourage the researchers to expand their efforts towards developing a tool that can advise which drug to take instead, without just relying 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 subjects in the study were comparatively young (average age 27) and mostly (73%) female, so they are now aiming to replicate the study in a much bigger 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 about 30 minutes and is non-invasive. It’s not generally available at the moment, but that may change if this test lives up to expectations”.