A study published Tuesday is the latest to suggest that the viral disease shingles may be harmful to long-term brain health. Scientists showed that people who experience shingles are about 20 percent more likely to experience cognitive decline afterward. The findings appear to support a growing belief that the shingles vaccine could help prevent dementia.
Shingles is caused by the Varicella Zoster Virus (VSV), the same germ that causes chickenpox in children and adolescents. After recovery from chickenpox, the virus often remains dormant and survives in the nervous system. Years, usually decades later, about one-third of people with chickenpox experience reinfection with the virus, known as shingles. Shingles is no easy treat, often causing excruciating pain, rashes, and other symptoms for up to five weeks. Some people may develop lingering nerve pain that can last for years.
Some research suggests that VSV and other bacteria lurking in the brain may cause subtle neurological disorders, particularly an increased risk of Alzheimer’s disease and dementia. However, this remains controversial, and several studies have failed to support such an association. Scientists at Brigham and Women’s Hospital led this latest study, hoping to shed more light on the potential relationship between shingles and poor brain health.
The researchers analyzed data from three large studies that actively tracked the long-term health of nursing and health care workers (known as prospective studies). As part of the studies, participants were periodically asked about their cognitive health and whether they had ever had shingles. In total, about 150,000 people were included in the analysis.
The researchers found that people who reported having shingles were significantly more likely to report cognitive decline. Even after accounting for other factors, they found that having shingles was associated with a 20 percent higher risk of subjective cognitive decline in both men and women. The associated risk was even higher in men who carried the APOE4 gene, a common genetic variant already known to increase the risk of Alzheimer’s disease. The study results were published Tuesday in the journal Alzheimer’s Disease Research and Treatment.
While this study alone cannot prove a causal link between shingles and cognitive decline, it is the latest evidence to support it. For example, in late July, British scientists found that people who received the latest shingles vaccine, Shingrix, were less likely to develop dementia over a six-year period compared to those who received the older, less potent shingles vaccine. Shingrix is already highly effective in its primary role, providing more than 90% protection against shingles for at least seven years. Previous research from the Brigham and Women’s Hospital team has also shown that shingles may increase the risk of long-term cardiovascular disease. So, taking that and these latest findings into account, the researchers say preventing shingles may be more valuable than currently thought.
“Our findings demonstrate the long-term consequences of shingles and highlight the importance of public health efforts to prevent and promote shingles vaccination,” researcher Sharon Curhan, an assistant professor of medicine at Brigham and Women’s Hospital, said in a hospital statement. “Given the growing number of Americans at risk for this painful and often disabling disease, and the availability of a highly effective vaccine, shingles vaccination may represent a rare opportunity to reduce the burden of shingles and perhaps subsequent cognitive decline.”
Chickenpox was once so common that, without vaccination, roughly one in three Americans over the age of 50 is expected to develop shingles in their lifetime. Considering how painful an experience shingles can be, preventing it with two simple injections is a no-brainer. Keeping your brain sharper as you age is just an added bonus.
