Dear Doctor: Pretty much everyone I know gets cold sores from time to time. Now I see a study saying that cold sores are somehow connected to Alzheimer's. Can you explain?

Dear Reader: As researchers have worked to understand Alzheimer's disease, the results of some studies have suggested a link to certain infections, including oral herpes, or cold sores. Pneumonia, chronic inflammation and infection with spirochete bacteria, which causes Lyme disease and can be associated with some types of gum disease, were implicated as well. Initially scientists noticed a higher incidence of Alzheimer's among people who also reported having contracted one or more of these infections. It was unclear whether the infections themselves were linked to Alzheimer's, or whether people with Alzheimer's were simply more prone to infection.

Now, a new study draws a clearer line between Alzheimer's disease, a devastating form of dementia, and the herpes simplex virus 1, which causes cold sores. Published last fall in the journal Frontiers in Aging Neuroscience, the study cited being infected with herpes simplex virus 1, also known as HSV1, as a major risk factor for developing Alzheimer's disease. In the new study, which consists of a review of decades of research, including her own, a scientist from England's University of Manchester thinks that up to half of all cases of Alzheimer's disease have a direct connection to HSV1.

An estimated 5.7 million Americans are now living with Alzheimer's, with a new diagnosis being made every minute. At this time there is no cure for the disease, and no reliable ways to manage it. When it comes to HSV1, between 50 and 80 percent of adults in the United States are believed to be infected with the virus. It is spread through contact with the oral secretions of someone who has an active infection, whether through direct contact or by sharing an object, like a glass or a toothbrush. Once infected, a person has the virus for life. However, much of the time it lies dormant. Some people can have the virus and never develop symptoms. Others can have outbreaks that range from occasional to frequent.

The thinking behind the link between HSV1 infection and Alzheimer's is that, as our immune systems weaken with age, the oral herpes virus is able to travel to the brain. Another piece of the puzzle is a version of a gene known as APOE, which plays a role in the manufacture of lipoproteins. It appears that the herpes virus either reactivates more frequently in people who are carriers of that particular gene variant, or that the reactivation is more harmful. Either way, the result is believed to cause changes within the brain tissue that lead to Alzheimer's.

Considering how many of us get cold sores, these new developments can be unnerving. That's why it's important to note that these findings are still preliminary, and more research is needed. The very good news is that, should the HSV1 theory prove to be correct, it gives scientists their first real line of attack against Alzheimer's disease, in the form of antiviral drugs. It even opens the door to the development of an anti-Alzheimer's vaccine.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I recently read that more than 30 students at a school in North Carolina all got chickenpox during an outbreak. Growing up, I got chickenpox, too, before there was a vaccine. Is the vaccine really that necessary for kids? Like I said, I got chickenpox as a kid and turned out fine!

Dear Reader: It's true that most children who develop chickenpox, a highly contagious disease caused by the varicella-zoster virus, go on to make a full recovery. Most often the virus causes an itchy rash that is often accompanied by a fever, headache, and some aches and pains.

However, that's not the whole story. First, it's important to note that from 2 to 6 percent of children who become infected with the chickenpox virus go on to develop complications as a result of the illness, some of them serious. These include pneumonia, bacterial infections, infections of the brain or the blood, and can lead to death. It's when you look beyond the individual consequences and consider the community that chickenpox becomes a health threat far more widespread than an individual child stuck at home for a few weeks with a rash and a fever.

Those at risk of grave complications from a case of the chickenpox include infants under 12 months old, who are too young to receive the vaccine and whose immune systems are not yet fully developed. The same goes for the elderly, whose immune systems become less robust as they age. Also at risk are people whose immune systems are compromised, such as someone undergoing cancer treatment or someone who is HIV-positive.

For a pregnant woman, a case of chickenpox prior to her 20th week can result in health complications for her unborn baby, including scars, eye problems, malformed limbs, poor growth, small head size and delayed development. When the virus is contracted in the third trimester, there is a chance of problems with the baby's central nervous system. The risk is small -- just 1 to 2 percent -- but with safe and effective vaccines available, it's unnecessary. Again, it's all about caring for one's wider community.

When it comes to prevention, the Centers for Disease Control and Prevention recommends that children get an initial dose of chickenpox vaccine between the ages of 12 and 15 months. This should be followed by a second dose of the vaccine between the ages of 4 and 6 years. For people who are 13 or older and have either never been vaccinated, or have never had chickenpox, the recommendation is two doses of the vaccine, given a minimum of 28 days apart. It's true that, despite receiving the vaccine, some people do go on to contract the disease. When that happens, symptoms are usually milder, meaning there are fewer blisters and often no fever. The illness will also typically be of shorter duration.

Most insurance plans will cover the chickenpox vaccine. If not, the Vaccines for Children Program offers help to individuals who qualify. For more information on this program, go to cdc.gov/features/vfcprogram.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I read that a doctor knew that a woman had thyroid cancer just by seeing her neck on TV. Why was a visual diagnosis so easy? What happens next?

Dear Reader: The incident you're referring to took place in the spring of 2018, when a head and neck surgeon from New York was watching "Beachfront Bargain Hunt," a popular real estate show on HGTV. He noticed an area of swelling on the front of the home buyer's throat; when she turned her head or stretched her neck to look upward, the swelling became prominent enough that he believed it could be a thyroid mass.

Unsure of how to find the woman, he posted his concerns to his Facebook page. With the power of the internet, the surgeon and the home buyer were quickly put in touch with each other. He explained his suspicion and urged her to undergo diagnostic tests, specifically a sonogram and a fine needle biopsy. She followed his advice, learned that she did indeed have a malignant tumor, and immediately sought appropriate treatment.

Interestingly, this was not the first time that thyroid cancer has been diagnosed on HGTV. Several years prior, a nurse watching the popular home renovation show "Flip or Flop" discerned what she believed to be a tumor on the neck of one of the hosts. Her concerns proved to be correct. The tumor was malignant, and the host underwent successful treatment for his thyroid cancer.

The reason these tumors were visible is due to the location of the thyroid gland, which sits below the Adams apple and is just beneath the skin. The thyroid measures about 2 inches across and consists of two main lobes, which make it appear somewhat like a bow tie, or a butterfly. The gland produces the hormones used by the body to regulate metabolic rate. It also contains specialized cells that produce calcitonin, a hormone that plays a role in managing blood levels of calcium and phosphate. Diseases of the thyroid such as Graves' disease, hyper- or hypothyroidism, and thyroiditis often cause the entire thyroid to swell, which is referred to as a goiter. Thyroid cancers are more often asymmetrical swellings, and thus can be distinctive.

In addition to a visible tumor, symptoms of thyroid cancer can include trouble swallowing, difficulty in breathing, a persistent cough in absence of a cold and pain in the front of the neck that may radiate up to the ears. When thyroid cancer is suspected, diagnostic tests may include imaging of the gland, blood tests, a radioiodine scan to test thyroid function, and a biopsy to search for cancer cells. Depending on the type of cancer that is present, as well as the stage at which it is identified, treatment consists of surgery, radioiodine or hormone therapy, chemotherapy or radiation. Targeted therapies that enlist the aid of the immune system to fight the cancer are also now being used.

The good news is that the most common types of thyroid cancer are very treatable, with five-year survival rates of 98 percent. Both of the individuals in the HGTV diagnoses have reported successful treatment.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)