Your Brain Could Soon Predict Antidepressant Side Effects—And a New Pill Offers Hope for Low Libido

A simple 30-minute brain test could soon help doctors predict whether antidepressants will cause sexual problems before you even start taking them. Meanwhile, the Food and Drug Administration (FDA) has approved the first medication specifically designed to boost libido in postmenopausal women, offering new hope for the millions experiencing low sexual desire.

How Does the Brain Test Work?

The breakthrough involves using an electroencephalogram (EEG)—a noninvasive test that places small electrodes on your scalp to record brain activity. Researchers discovered they can measure something called Loudness Dependence of Auditory Evoked Potentials (LDAEP), which tracks how your brain responds to sounds at different volumes.

"It takes about 30 minutes and is non-invasive," said Dr. Kristian Jensen, lead researcher at Copenhagen University Hospital. The test works because auditory perception depends on serotonin levels in the brain—the same neurotransmitter that antidepressants target.

In a study of 90 participants with major depressive disorder, researchers found that lower LDAEP measures (indicating higher serotonin levels) predicted orgasmic dysfunction from eight weeks of escitalopram treatment with 87% accuracy.

What Are the Key Findings About Sexual Side Effects?

The research addresses a major problem: about 25% to 80% of people taking antidepressants experience sexual side effects to some degree. These problems have been documented since 1960, but until now, there was no way to predict who would be affected.

The brain test revealed several important patterns:

• Orgasmic Function: The test predicted orgasmic dysfunction with 87% accuracy in people taking escitalopram
• Libido Impact: While it didn't strongly predict reduced libido, it was slightly associated with the severity of decreased sexual desire
• Baseline Function: Participants' test results didn't correlate with sexual function before starting medication, suggesting the drugs themselves caused the problems

"This could enable a more precise approach to depression treatment," Jensen explained. The team is now conducting a larger study with 600 participants to validate these findings.

What's New for Postmenopausal Women?

On December 15, 2025, the FDA expanded approval of Addyi (flibanserin) to treat hypoactive sexual desire disorder (HSDD) in postmenopausal women under age 65. The drug was previously only approved for premenopausal women in 2015.

This approval addresses a significant need: between 40% to 55% of women going through menopause experience low sexual desire, and about 9% of postmenopausal women have HSDD.

"The group of women where I get the biggest complaints of decreased libido is in the 50 to 60 year old age bracket, so potentially this could be a very important medication for them," said Dr. G. Thomas Ruiz, a board-certified OB/GYN at MemorialCare Orange Coast Medical Center.

Addyi works differently from hormonal treatments—it's a non-hormonal medication that affects neurotransmitters in the brain to help regulate mood and increase sex drive. After taking it for a month, dopamine and serotonin levels are enhanced, which increases sexual desire.

Are There Risks and Alternatives?

Both treatments come with important considerations. The brain test, while promising, isn't a direct measure of serotonin activity and needs validation in larger studies with placebo controls.

Addyi carries a "black box" warning because it can cause severe low blood pressure or fainting when combined with alcohol or certain medications. Other side effects include constipation, dizziness, dry mouth, headache, nausea, and tiredness.

For women seeking alternatives, hormone optimization can be extremely effective. "Estradiol is extremely effective for this, with the estradiol patch and compounded cream being my top two choices," explained Dr. Prudence Hall, an OB/GYN and author of "Radiant Again & Forever." She noted that when testosterone and thyroid hormones are optimized, "women report that their sexuality returns to youthful levels."

"Previously, I could prescribe it off-label for postmenopausal women, but they were unfairly denied insurance coverage. Now, with this official approval, we can finally expect insurers to cover this necessary treatment for a wider population of women," said Dr. Susan Marie Pacana, a minimally invasive gynecologic surgeon.