Viruses and Alzheimer's
For almost twenty years, Dr. Ruth Itzhaki, Professor of Molecular Neurobiology at the University of Manchester in England, has been exploring possible links between viruses and Alzheimer's. Viruses are tiny infectious particles that attach themselves to and penetrate cells, then use the capabilities of those cells to reproduce. They can cause diseases like colds, flu and AIDS, or they can just sit there, remaining dormant or latent for long periods of time. A latent virus can become active when triggered by stress, other infections or environmental factors.
For a virus to contribute to the development of Alzheimer's, Dr. Itzhaki reasoned, it would have to be very common in humans. And because Alzheimer's appears to develop over a long period of time, it would make sense to look for a virus that has long periods of latency, but could periodically be reactivated and cause damage.
One family of viruses fits her criteria: herpes. There are over 100 types of herpes, of which eight infect humans, causing diseases ranging from chickenpox and shingles to cold sores and mononucleosis. Most people have some type of herpes, even though they may have no symptoms.
We will review one type of herpes which is particularly suspected in having tight causal links with Alzheimer's in more details.
About Herpes Simplex Virus1
Herpes Simplex Virus Type 1 (HSV1) is especially common in humans. It is also regularly referred to as cold sores, fever blisters, oral herpes or herpes labialis. It is a viral infection of the skin that may occur once or return again and again. This happens when the virus is cleared from the skin by the immune system it hides in the nerves and is never completely removed from the body. Herpes outbreak infections are very common. It is estimated that nine out of ten people have been exposed to herpes outbreaks and many of these don't even know they have it. Those who carry herpes can spread the disease without even knowing it.
Herpes simplex begins as a group of small red bumps that blister and preceded by itching and burning of the area. The blisters begin to dry up after a few days and form a yellow crust. The crust then falls off and the redness slowly goes away. The whole process takes about 10-14 days. Scars rarely form.
What causes Herpes Simplex Virus1?
- Cold sores are generally contracted from skin to skin contact with an infected area.
- People can catch HSV1 by sexual contact such as kissing a person with a cold sore or sharing a drinking glass or utensils
- Family members should not share towels or linen with someone who has an outbreak of herpes on the genitalia or cold sores. Herpes outbreaks can spread from person to person even when an infected individual has no outbreak or symptoms.
- Once infected with cold sores, the virus remains inside the body in a latent (sleeping) state. Throughout a person's life the virus can then become "activated" causing a cold sore recurrence.
What causes or "activates" a Cold sores or fever blisters recurrence?
If you've had cold sores before, it can be hard to tell what might make them come back. Below are some factors that may trigger it to return:
- Stress
- Sun (Exposure of the area to strong sunlight)
- Incorrect diet
- Fever
- Menstruation Cycle
- Fatigue (not getting enough rest)
- Being run-down
- Pregnancy
- Drinking a lot of alcohol
- Ultraviolet light
- Skin irritation (such as sunburn)
- Certain foods
- Temperature extremes
Herpes Simplex Virus1 and Alzheimer's
Whilst it is not the case that everyone with herpes will indeed develop Alzheimer's, there is a fairly strong linkage. It all comes down to a particular gene which appears to damage a key part of the nervous system which is responsible for keeping Alzheimer's at bay.
What this means is that whilst herpes does not directly cause Alzheimer's, it doesn't weaken the system which Alzheimer's attacks, and therefore leaves you more vulnerable than someone who does not have the HSV1 disease.
Over the past several years, compelling evidence has surfaced linking HSV1 to Alzheimer's disease. In 2008, Canadian researchers Luc Letenneur and Karine Peres demonstrated a dramatic increase in antibodies directed against HSV1 in Alzheimer's patients compared to age-matched individuals without the disease.
University of New Mexico (UNM), Brown University, and House Ear Institute (HEI) recent study supplied even more conclusive results to support the theory of this causal relationship. "It's no longer a matter of determining whether HSV1 is involved in cognitive decline, but rather how significant this involvement is. We'll need to investigate anti-viral drugs used for acute herpes treatment to determine their ability to slow or prevent cognitive decline," comments Elaine Bearer, M.D., Ph.D., Harvey Family Professor and Vice Chair for Research, Department of Pathology, UNM School of Medicine.
Professor Ruth Itzhaki has explored the relationship of HSV1 to Alzheimer's disease in great depth. In her landmark article published in 2008 entitled "Herpes Simplex Virus Type 1 in Alzheimer's disease: The Enemy Within," Dr. Itzhaki revealed that HSV1 infects the brains of 90 percent of adults. If HSV1 causes Alzheimer's, this high rate of infection would be a necessary characteristic in light of the very high prevalence of Alzheimer's disease. Further, she points out, HSV1 can remain latent in the nervous system lifelong and may undergo periodic reactivation causing persistent brain inflammation. As an example, HSV1 is the cause of recurrent fever blisters that occur when the virus gets activated in the brain. Undoubtedly the most compelling evidence linking HSV1 to Alzheimer's disease comes from her recent discovery of HSV1 DNA actually located exactly within the beta amyloid plaque, the so-called "hallmark" of the disease.
So compelling are these findings that Dr. Itzhaki has concluded, "Our present data suggest that this virus is a major cause of amyloid plaques and hence probably a significant etiological factor in Alzheimer's disease. They point to the usage of antiviral agents to treat the disease and possibly of vaccination to prevent it."
How It Happens?
One of the theories of this relationship has to do with the way that the herpes virus interacts with the receptors of lipoproteins. In partnership with the gene � Allele, the system which is responsible for motor functions is gradually degraded � not to the point where it doesn't work, but instead to the point where it is left open to developing Alzheimer's more quickly.
Interestingly, when the Allele gene is not present, there is no effect of herpes on the development of Alzheimer's, meaning that obviously the two need to be in sync with each other to have any tangible effect.
Reviewing the possible causes for the devastating HSV1 role in Alzheimer's, Dr. Itzhaki mentioned that the complete mechanism on how HSV1 might damage the brain is still unclear. It could be via inflammation and oxidation. Oxidation is when unstable molecules called oxygen free-radicals combine with other molecules. In the same way that rusting damages metal, oxidation can damage brain cells. Dr. Itzhaki says that oxidation has been found in HSV1 infected cells in the lab and in brain cells harboring latent HSV1.
"We think inflammation must be a major factor," she says. She lays out the hypothesized chain of events: "When HSV1 is latent (i.e. in a dormant state) in the brain, it can be activated by inflammation of the brain. The latter can occur when somebody has an infection, or is stressed, or immunosuppressed. The virus then augments the inflammation there. So other viral or bacterial infections (not necessary in the brain) can cause indirect trouble."
Herpes Simplex Virus1 Treatment
Currently, there are no cures or vaccines for the herpes simplex virus. However, avoiding precipitating factors, such as sunburn and stress, can help prevent additional outbreaks. There are established treatments available to help decrease healing time, reduce pain associated with the lesion, and in specific cases, suppress the recurrence of the virus.
Nondrug therapy
Frequent hand washing will help reduce the spread of the virus to other parts of the body or to other people. Also, applying cool, moist compresses to the lesion may decrease pain and keep the lesion from drying and cracking.
Some recommendations on how to minimize the risk:
- Replace your toothbrush because it can harbor the virus for days and re-infect you with another cold sore. Don't keep your toothbrush in the bathroom. The moisture in the bathroom prolongs the life of the virus causing cold sore in your toothbrush. In short, keep your toothbrush dry.
- Avoid excessive arginine-rich food such as chocolate, cola, peas, grain cereals, peanuts, gelatin, cashew and beer.
- Supplement your daily diets with good food sources of lysine such as dairy products, potatoes and brewer's yeast.
- Lemon has been used to stop fever blisters or cold sores over decades in Europe. You can cut a small slice of lemon and place it either on your cold sore and leave it there as long as you can. Change it as often as possible with a fresh slice.
- Apple cider vinegar is one of the oldest home remedies for cold sores, herpes and wounds. It should not be used pure on open sores because it can sting a lot. Pour a few drops on a cotton ball and apply it on your cold sore or blister. You can also mix it with lemon juice to increase its potential.
- Garlic is a broad-spectrum antibiotic, killing bacteria, fungus, yeast, viruses and parasites. A scientific study has confirmed that garlic can destroy several virus types on contact including herpes type 1.
- Ice cubes are a great way to ease the pain associated with a cold sore. Simply rub an ice cube directly onto the cold sore for a few minutes when it first begins to appear. Repeat this every 10 minutes for about an hour or so.
- The juice from an aloe plant can help ease the pain from a cold sore. Simply rub aloe juice directly onto the infected area for some fast relief. Aloe gels can also be used instead of fresh aloe juice.
- Use petroleum-based products all over the infected area. This will help prevent any secondary infection from bacteria as well as expedite healing.
- An effective remedy is to apply tea bags to the affected area. This facilitates the tannic acid in the tea to act against the virus and prevent its further development. Another effective method is to press a warm tea bag on the cold sore. A five-day application will make the sores disappear.
- If powered common salt is applied to the affected area by a moistened index finger, it'll make cold sores disappear in two to three days.
- Herbs like herbal sage, tea tree oil and the herbal sedative violet have been used as treatments for cold sores. Sage leaf tea with a small ginger root piece or ginger powder is effective against this condition.
- Avoid physical contact with the cold sore area. Touching, rubbing, and scratching cold sores can not only increase bacterial infection but also unwittingly spread the virus to other areas of the face and possibly infect other persons.
- Clean the cold sore with a washcloth, soap, and warm water. This will minimize itching as well as prevent the virus from spreading.
- Avoid salty and acidic foods like lemon and potato chips as these will aggravate cold sores and become more painful.
- Use an anesthetic ointment to alleviate the pain.
- Recognize cold sore symptoms to prepare you for it, as well as be aware of the conditions that trigger your cold sore outbreak. Stress, weather extremes, the menstrual cycle. All these can cause an outbreak. Avoid too much exposure to direct sunlight, and use a good sunscreen.
- Get lots of rest. A well-rested person would have higher immunity against cold sores.
- Take vitamin supplements, especially those with a substantial amount of anti-oxidants and Vitamin B. Vitamin B deficiency has been found to have a direct link with cold sore outbreaks, and anti-oxidants are essential for a healthy body.
- Exercise. Not only does it bolster your immune system, it is an effective way to ward off stress, one of the common triggers of cold sores.
Over-the-counter (OTC) topical medications
Most topical OTC products provide symptomatic relief only; they do not decrease healing time. Using topical anesthetics that contain benzocaine (5%-20%), lidocaine (0.5%-4%), tetracaine (2%), or dibucaine (0.25%-1%) will help relieve burning, itching, and pain. The most commonly recommended products are Lipactin gel and Zilactin. It is important to keep in mind that these topical anesthetics have a short duration of action, usually only lasting 20-30 minutes. Skin protectants, such as allantoin, petrolatum, and dimethicone-containing products help keep the lesion moist and prevent cracking of the lesion. Sunscreen-containing lip balms may also help prevent additional outbreaks if the sun is a precipitating factor. For additional pain relief, using aspirin, ibuprofen (Advil), or acetaminophen (Tylenol) may be beneficial. These products should be used according to package directions.
Docosanol 10% cream (Abreva) is the only OTC topical product that is known to decrease healing time when applied at the first sign of recurrence (for example, the prodrome or tingling sensation). Docosanol is applied five times per day until the lesion is healed. Common side effects include rash and itching at the site of application.
Prescription-strength topical medications
Treatment with topical acyclovir (Zovirax 5% cream) or penciclovir (Denavir 1% cream) will reduce healing time by approximately half a day and decrease pain associated with the lesion. Topical treatment is limited in its effectiveness because it has poor penetration to the site of replication of the virus, and therefore is restricted in its healing ability. Acyclovir cream should be applied five times per day for four days, and penciclovir cream should be applied every two hours while awake for four days. In August 2009, the FDA approved a cream containing acyclovir and a topical steroid, which reduces healing time by approximately one day.
Oral prescription-strength medications
The current FDA-approved oral antiviral medications used in the treatment of herpes simplex virus in adults are acyclovir, valacyclovir (Valtrex), and famciclovir (Famvir). Famciclovir has not been tested in children with cold sores. These oral medications have been shown to decrease the duration of the outbreak, especially when started during the prodrome (symptom onset before the actual condition becomes fully evident). The medications are generally well tolerated with few side effects. Most common side effects include headache, nausea, and diarrhea. Treatment is only for one day with valacyclovir and famciclovir. Valacyclovir is given as 2 grams orally every 12 hours for one day, and famciclovir is given as 1,500 milligrams orally for one dose. Acyclovir is given as 400 mg orally five times per day for five days. Acyclovir, valacyclovir, and famciclovir are considered relatively safe and effective when used in pregnancy, although topical treatment would be preferred when appropriate. Acyclovir and valacyclovir have been used while breastfeeding. However, pregnant women and nursing mothers should contact their physician or pharmacist prior to using any medication.
People who have more than two outbreaks in four months, which significantly affect their daily lives, should consider chronic suppressive therapy. The FDA has approved the use of oral valacyclovir daily to prevent recurrence of the herpes simplex virus in people with normal immune systems and famciclovir in people with suppressed immune systems.
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