Can Zika Virus Promote Dementia?
The answer to the above question is a definite maybe. The thought that Zika virus infection might have a deleterious effect on the adult brain, apart from its know tragic effects on the developing fetal brain, stems from some very recently published research. The new research shows that Zika virus can kill stem cells in the adult (mouse) brain, just the way it does so in fetal brains.
Although acute brain dysfunction is not a described part of the syndrome adults get when they have Zika virus infection, this research naturally leads to the question of whether these individuals might show later problems with memory, learning and other brain functions.
To examine this provocative question, let’s first see what the research showed. The researchers infected the mice with Zika virus by inoculating their blood. Since Zika is “neurotropic,” the virus found its way into the central nervous system. There, adult neural stem cells were affected with cell death and reduced proliferation. The researcher’s conclusion was that “although Zika virus is considered a transient infection in adult humans without marked long-term effects, there may in fact be consequences of exposure in the adult brain.”
Two areas in the adult mouse brain contain neural stem cells: the subventricular zone of the anterior forebrain and the subgranular zone of the hippocampus. The latter area is critical to memory and the former is important for general brain maintenance and repair. Since neurons do not divide, neuronal stem cells are called upon to differentiate and replace lost or injured neurons. This same process is known to occur in humans, too.
Only long-term clinical trials will be able to show if acute Zika virus infections will have late effects on adult human brain health.
Winkler G. Weinberg, MD