Caution: Frequent Sexual Activity Could Result in Brain Modifications and Dementia

A recent study is highlighting worries about an uncommon yet serious risk associated with a prevalent sexual practice — the possibility of brain injury and dementia resulting from the herpes simplex virus type 1 (HSV-1).

HSV-1, the virus that causes oral herpes, is carried by nearly four billion individuals globally. While it predominantly leads to cold sores, researchers have now discovered a concerning pathway through which the virus can access the brain — via the nasal route during oral sexual activity.

Professor Deepak Shukla from the University of Illinois Chicago, who spearheaded the research, noted that HSV-1 particles can enter the nasal cavity when it contacts the saliva or skin of an infected partner during oral sex. Once in the nasal cavity, the virus may travel directly to the brain, posing risks for encephalitis, brain damage, and potentially dementia.

The study, published in the journal *mBio*, also pinpointed a significant human enzyme, **heparanase (HPSE)**, which may exacerbate nasal HSV-1 infections. While heparanase typically helps in removing damaged cells, HSV-1 seems to exploit the enzyme to amplify inflammation in the brain.

“For most individuals, HSV-1 leads to occasional cold sores and is not harmful,” stated Professor Shukla. “But if the infection spreads through the nasal route to the brain, it can become much more severe.”

To investigate this hypothesis, Shukla’s team performed experiments on mice by introducing HSV-1 into their noses. Mice with regular heparanase levels developed severe symptoms, including nasal swelling, respiratory issues, and ultimately death. Brain analyses showed nerve damage, heightened inflammation, and abnormal activity in regions associated with smell and viral entry.

Behavioral alterations were also observed, including memory loss, anxiety-like behaviors, and balance issues — all occurring within six months post-infection.

Although herpes simplex encephalitis (HSE) is uncommon — impacting about two to four individuals per million — researchers suspect that cases of nasal HSV-1 are probably underreported. The virus may remain latent in the brain and contribute to conditions such as Alzheimer’s disease later in life.

Shukla stressed that the effects can differ widely based on a person’s immune response and the frequency of outbreaks.

“Our findings serve as a warning,” he asserted. “Unchecked herpes can result in long-term behavioral challenges, motor dysfunction, and coordination issues. It’s crucial to comprehend how the virus operates and the severity it can reach under certain circumstances.”