According to researchers at the Asan Medical Center in Seoul, South Korea, patients who have left their shingles symptoms untreated have an increased risk of dementia.

The researchers pulled data from South Korea’s National Health Insurance Service during the period of 2002 to 2013 and analyzed the incidence of dementia in patients with shingles who either did or did not receive treatment.

The data demonstrated that the rate of dementia in those patients who did not receive treatment was 1.3 times higher than those who did receive treatment. Additionally, those patients who received treatment with antiviral drugs had a reduced risk of dementia by about one-quarter.

Shingles is a viral infection caused by a reactivation of the chickenpox virus, which lurks in the nerve cells following infection in childhood. It can then spread through the nerve cells as the body's immunity decreases. According to the researchers, patients who show signs of blistering and pain symptoms should receive treatment with an antiviral agent within 72 hours.

However, if treatment is delayed, a secondary infection or chronic neuralgia becomes more possible, even if the blisters and rashes disappear, the researchers explained in the study.

To explain this correlation, the researchers hypothesized that the neuro-invasive nature of the shingles virus may cause local or systemic inflammation and immune system abnormalities, which could potentially lead to the development of dementia.

Additionally, the shingles virus may use an insulin-degrading enzyme as a receptor upon entering the cells, the researchers noted. This could be another reason for the increased risk of dementia.

"This study is significant because it uncovered the epidemiological linkage between common shingles and dementia by using big data," said Kim Sung-han, MD, PhD, a co-lead of the study and professor at the Asan Medical Center, in an interview with Korea Biomedical Review. "However, the causal relationship between the 2 diseases have not been confirmed definitively, so further studies are needed."

Kim noted that it is critical that patients suffering from shingles receive antiviral treatment.

"Vaccination can reduce the chance of getting shingles by 60%," he said in the interview. "People over 50 who are prone to shingles due to reduced immunity should receive the vaccine in advance and increase their immunity through adequate nutrition, sleep, and stress management."

Han-soo L. 'Untreated shingles can increase risk of dementia.' Korea Biomedical Review. July 23, 2020. Accessed July 30, 2020.