New study reveals brain differences in sexual appetite disorders in men and women

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A recently published study Scientific reports has shed light on the different neural mechanisms underlying diminished sexual desire disorder (HSDD) in men and women. Researchers found significant differences in brain activity between the sexes, offering new insights into the disorder and paving the way for more targeted treatments.

Sexual desire is a fundamental aspect of human life and is critical for emotional connection, intimacy, and overall well-being. HSDD, characterized by a persistent lack of sexual interest that causes significant distress, affects approximately 10% of women and 8% of men. Despite its prevalence, the disorder is relatively understudied, particularly in men. Current treatment options in the United States are only available to women, highlighting the need for better diagnostic and therapeutic options for men.

The prevailing theory of HSDD, developed from studies of women, posits that excessive activation of higher-level brain regions responsible for introspection and self-control leads to reduced activity in lower-level regions involved in emotional and sexual processing. However, this theory does not hold for men with HSDD. To fill this gap, the researchers wanted to directly compare the neural mechanisms of HSDD in both sexes using functional magnetic resonance imaging (fMRI).

“We want to better understand the brain regions that are disrupted in people with distressingly low sexual desire,” said study author Alexander Comninos, professor at Imperial College Healthcare NHS Trust and Imperial College London. “Better understanding will lead to better treatments, as there are no approved treatments for men and treatments for women (available only in North America) have limited effectiveness and carry unwanted side effects such as drowsiness, nausea and syncope, as well as interactions with alcohol.”

For their new study, researchers recruited 32 premenopausal women and 32 men who had been diagnosed with HSDD and who had no history of psychiatric illness or were taking medication. The participants, who were in committed relationships, underwent a detailed screening process that included medical history, psychometric questionnaires and blood tests to ensure normal health and rule out endocrine abnormalities.

During the study, participants watched sex videos and control (exercise) videos while undergoing fMRI scans. The sex videos were selected based on focus group ratings of healthy individuals to ensure they were arousing. After each video, participants rated their level of arousal. The fMRI scans measured brain activity and focused on regions associated with sexual and emotional processing.

The study revealed both similarities and differences in the brain activation patterns of men and women with HSDD. Both sexes showed similar overall activation patterns in response to sexual stimuli, with increased activity in regions such as the striatum, visual cortex, cerebellum, and anterior cingulate cortex. These areas are known to be involved in sexual processing.

However, there were significant differences in the magnitude and specific areas of activation. Women with HSDD showed greater activation in limbic regions such as the amygdala, striatum, and thalamus, which are associated with emotion processing and sexual motivation. In contrast, men showed greater activation in the visual cortex, suggesting increased sensitivity to visual sexual stimuli.

These results suggest that women with HSDD have more emotional and motivational disturbances related to sexual desire, whereas men may have a disturbance in processing visual sexual stimuli into emotional responses. This difference indicates a possible disconnect between visual and emotional systems in men with HSDD.

“In this study, we compared brain responses to erotic videos in women and men with distressingly low sex drive,” Comninos told PsyPost. “Overall, the brain regions disrupted in distressingly low sex drive appear to be similar in women and men. However, our data suggest some interesting sex differences. In women, the predominant finding is a top-down inhibition of sexual response, which is consistent with previous literature on women. This was demonstrated by the hyperactive frontal gyrus and associations with lower sexual function on psychometric testing in women.”

“However, in men, we observed increased activation of the visual cortex (compared to women), suggesting that visual attention to the erotic stimuli is not effectively relayed to the emotional centers involved in sexual responses. Taken together, 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 study comes with some caveats. The lack of a control group with normal sex drive limits the ability to fully understand the differences between people with and without HSDD.

Future research should include a control group to directly compare brain activity patterns. Investigating therapies that target specific brain regions or connectivity patterns could also lead to more effective treatments. For example, therapies that improve the connection between visual and emotional centers in the brain could help men with HSDD, while approaches that reduce hyperactivity in higher brain regions or increase activation in limbic regions could be effective in women.

“Our main goal is to develop much-needed, better-tolerated and effective treatments for individuals seeking help for their distressingly low sexual desire,” said Comninos. “We have previously shown that kisspeptin, a reproductive protein, when administered, can improve sexual brain processing in both women and men with distressingly low sexual desire. In fact, according to our studies, it even appears to have an erectile effect in men with low sexual desire and is very well tolerated.”

“The current study expands our understanding of the central neural disturbances that occur in low sexual desire and gives us confidence that kisspeptin may indeed have therapeutic potential in women and men, as their disorders are broadly similar. However, it is still early days and we continue to work tirelessly on this as funding allows, as it is an extremely serious problem for many people, negatively impacting their quality of life, relationships and, in some cases, fertility.”

Authors of the study “Women and men with distressingly low sexual desire exhibit sexually dimorphic brain processes” are 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.