Setback in Alzheimer’s Treatment Research
Efforts to find a viable treatment for Alzheimer’s disease have hit another roadblock. This time, the focus was on medications aimed at combating the herpes virus.
Researchers from Columbia University revealed underwhelming outcomes from their recent randomized trial. Cognitive function in individuals diagnosed with herpes and early-stage Alzheimer’s showed no improvement after antiviral treatment compared to those receiving a placebo. In fact, those on the antiviral therapy experienced a decline in cognitive abilities. While this doesn’t completely dismiss a possible connection between certain viral infections and Alzheimer’s, experts suggest that these antiviral drugs shouldn’t be regarded as dementia treatments.
“For individuals experiencing cognitive impairment, there is absolutely no, I emphasize no, efficacy for antiviral therapy,” remarked David Knopman, a clinical neurologist at the Mayo Clinic who was not involved in the study, in an interview.
Exploring the Viral Hypothesis
Alzheimer’s disease remains the most prevalent form of dementia, affecting more than 7 million people in the U.S.
This condition is marked by elevated levels of two misfolded proteins in the brain: amyloid beta and tau. However, researchers are still puzzled about how these proteins contribute to the disease’s development and what triggers the resulting brain damage.
Recently, some studies have posited that certain viruses might play a role in causing Alzheimer’s, leading to discussions around the so-called viral hypothesis. Evidence indicates that herpesvirus infections could potentially trigger the buildup of amyloid beta plaques in mice with human-like brain cells. There’s also a suggestion that people who succumb to Alzheimer’s disease are more likely to have herpesviruses in their brains than those without.
While these findings hint at a possible viral link, they aren’t definitive. If such viruses are indeed triggers for Alzheimer’s, tackling underlying infections could theoretically help in preventing or slowing down its progression. That was the hypothesis the researchers aimed to explore.
A Study That Missed the Mark
The trial involved 120 participants diagnosed with probable Alzheimer’s or showing mild cognitive impairment likely to ascend to Alzheimer’s. They also tested positive for herpes simplex virus type 1 or 2 antibodies. HSV-1 primarily causes cold sores, while HSV-2 is typically linked to genital herpes; either strain can lead to symptoms of the other.
Participants were given either a daily placebo or valacyclovir (commonly sold as Valtrex), a standard treatment for herpesvirus infections, over the course of 18 months.
At the conclusion of the study, the group receiving treatment experienced a considerably worse decline in cognitive function compared to the placebo group. Brain imaging indicated no improvement in neurological markers or overall neurodegeneration, either.
“Valacyclovir proved ineffective, correlating with cognitive decline for the primary outcome,” the researchers stated in their published paper.
What Lies Ahead for the Viral Hypothesis?
Despite the negative findings, this study doesn’t entirely eliminate the possibility that viruses can contribute to some Alzheimer’s cases.
It often takes time for the harmful brain changes associated with Alzheimer’s to become evident. This raises the possibility that by the time symptoms appear, it might be too late to treat infections that could have set off the disease many years in advance.
Researchers are currently exploring whether anti-amyloid drugs can hinder or delay the onset of Alzheimer’s in individuals genetically predisposed to the illness.
On a slightly more positive note, we do have effective vaccines that can prevent certain viral infections. Recent studies suggest that vaccinating individuals against shingles, which is triggered by a type of herpesvirus, may reduce the likelihood of subsequently being diagnosed with dementia.
“Could vaccinations provide a population-level benefit? Perhaps?” Knopman mused, mentioning his editorial that accompanied the study’s publication.
To clarify, further research is essential to establish a direct causal relationship between shingles and Alzheimer’s, as well as assessing the protective effects of vaccines. Nonetheless, this possibility offers a glimmer of hope amid otherwise discouraging news.
