There may be evidence that if you get cold sores often it may lead to memory loss later in life.

A study by Neurology says there might be a connection with cold sores and loss of memory. All bacteria infections are contributing to the loss of memory and according to the study might be the reason or one of them that leads to Alzheimer's disease.

The study was done in New York in 2013 and found that

if people had been exposed to various pathogens such as the herpes simplex type 1 virus that causes cold sores those people were more likely to have cognitive problems than people with lower levels of infection in the blood. All the results are published in the March 26 issue of Neurology, the medical journal of the American Academy of Neurology.

According to NBC News, The results showed that the people who had higher levels of infection had a 25 percent increase in the risk of a low score on a common test of cognition called the Mini-Mental State Examination.

Also in the article by NBC News, Dr. Mira Katan went on to say

"While this association needs to be further studied, the results could lead to ways to identify people at risk of cognitive impairment and eventually lower that risk," said Dr. Mira Katan, author of the study. "For example, exercise and childhood vaccinations against viruses could decrease the risk for memory problems later in life.”

I personally don't know what causes cold sores but I was always told by my grandpa if you eat a lot of acidic food, you should drink water to lower the acidic value in your body so you don't get a cold sore.'