A recent study published in Scientific reports shed light on the distinct neural mechanisms underlying hypoactive sexual desire disorder (HSDD) in men and women. Researchers discovered significant differences in brain activity between the sexes, providing new insights into the disease and paving the way for more targeted treatments.
Sexual desire is a fundamental aspect of human life, crucial for emotional connection, intimacy and overall well-being. HSDD, characterized by a persistent lack of sexual interest causing significant distress, affects approximately 10% of women and 8% of men. Despite its prevalence, this disease is relatively understudied, particularly in men. Current treatments are only available to women in the United States, highlighting the need for better diagnostic and therapeutic options for men.
The prevailing theory of HSDD, developed from studies of women, suggests that excessive activation of higher-level brain regions responsible for introspection and self-monitoring leads to reduced activity in lower-level regions involved in emotional and sexual processing. However, this theory does not take into account men with HSDD. To address this gap, researchers sought to directly compare the neural mechanisms of HSDD in both sexes using functional magnetic resonance imaging (fMRI).
“We want to better understand which brain regions are disrupted in individuals with low distressing sexual desire,” said study author Alexander Comninos, a professor at Imperial College Healthcare NHS Trust and Imperial College London. “Better understanding will lead to better treatments, because in men there are no approved treatments and in women, treatments (available only in North America) have limited effectiveness and cause unwanted side effects such as drowsiness , nausea and syncope, as well as interactions with alcohol.
For their new study, the researchers recruited 32 premenopausal women and 32 men, all diagnosed with HSDD and free of psychiatric illnesses and medications. Participants, who were in stable relationships, underwent a detailed selection process, including medical history, psychometric questionnaires and blood tests to ensure normal health and exclude endocrine abnormalities.
During the study, participants watched sexual and control (exercise) videos while undergoing fMRI scans. The sex videos were selected based on ratings from focus groups of healthy individuals to ensure they were arousing. After each video, participants rated their arousal level. The fMRI scans measured brain activity, focusing on regions associated with sexual and emotional processing.
The study found both similarities and differences in brain activation patterns between men and women with HSDD. Both sexes showed similar general patterns of activation in response to sexual stimuli, with increased activity in regions including the striatum, visual cortex, cerebellum, and anterior cingulate cortex. These areas are known to be involved in sexual processing.
However, significant differences emerged in the magnitude and specific regions of activation. Women with HSDD showed greater activation in limbic regions such as the amygdala, striatum and thalamus, which are associated with emotional processing and sexual motivation. In contrast, men showed greater activation of the visual cortex, indicating increased sensitivity to visual sexual cues.
These findings suggest that although women with HSDD may experience more emotional and motivational disturbances related to sexual desire, men may have difficulty transforming visual sexual cues into emotional responses. This difference indicates a potential disconnect between the visual and emotional systems in men with HSDD.
“In this study, we compared brain responses to erotic videos in women and men with low distressing sexual desire,” Comninos told PsyPost. “Generally speaking, the brain regions disrupted by low distressing sexual desire appear similar in women and men. However, our data suggest interesting gender differences. In women, the predominant finding is a descending inhibition of sexual response, consistent with previous literature in women. This has been demonstrated by overactive frontal gyrus and associations with lower sexual function in psychometric tests in women.
“However, in men we observed increased activation of the visual cortex (compared to women), suggesting that visual attention to erotic cues is not effectively relayed to the emotional centers involved in sexual responses Collectively, these data have clinical implications for the development of new diagnostic and therapeutic approaches for women and men seeking help for distressing low sexual desire.
But, as with any study, the new research comes with some caveats. The lack of a control group with normal sexual desire limits the ability to fully understand differences between individuals with and without HSDD.
Future research should include a control group to directly compare brain activity patterns. Studying therapies targeting specific brain regions or connectivity patterns could also lead to more effective treatments. For example, therapies improving the connection between the visual and emotional centers of the brain could benefit men with HSDD, while approaches reducing hyperactivity in higher cortical regions or stimulating activation in limbic regions could be effective for the women.
“Our main goal is to develop much-needed, better tolerated and effective treatments for people seeking help for their distressing low sexual desire,” Comninos said. “We have previously shown that the reproductive protein kisspeptin, when administered, can improve the brain’s sexual processing in women and men with distressingly low sexual desire. In fact, in men with low sexual desire, it even appears to have a pro-erectile effect according to our studies and is very well tolerated.
“The current study advances our understanding of the fundamental neuronal disruptions linked to low sexual desire and gives us confidence that kisspeptin may indeed have therapeutic potential in women and men, as their disruptions are broadly similar. However, it is still early days and we continue to work on this tirelessly, as funds allow, as this is an extremely important issue for many people, negatively affecting their quality their lives, their relationships and, in some cases, their fertility.
The study, “Women and men with distressing low sexual desire exhibit sexually dimorphic brain processing,” was authored by Natalie Ertl, Edouard G. Mills, Matthew B. Wall, Layla Thurston, Lisa Yang, Sofiya Suladze, Tia Hunjan, Maria Phylactou, Bijal Patel, Paul A. Bassett, Jonathan Howard, Eugenii A. Rabiner, Ali Abbara, David Goldmeier, Alexander N. Comninos, and Waljit S. Dhillo.