Herpes simplex virus linked to brain immune dysfunction and dementia risk

New research published in PLOS Pathogens suggests that herpes simplex virus type 1 (HSV-1) can reprogram immune cells in the brain, potentially contributing to cognitive decline. The study indicates that when HSV-1 enters the brain, it affects microglia—specialized immune cells responsible for maintaining brain health and removing damaged tissue.

Neuroscientist Kristi Niemeyer from the University of Colorado Anschutz noted that while these cells enter an emergency defense mode to fight the virus, this process may impair their ability to perform essential daily functions even after the virus is gone. This dysfunction is being investigated for its potential links to Alzheimer’s disease and a possible doubling of dementia risk.

Separately, medical experts warn of the dangers HSV-1 poses to newborns. Because infants have underdeveloped immune systems, contact with the virus—often spread through kissing or shared objects—can lead to life-threatening illnesses, high fevers, and severe oral sores.