Arquivo da tag: Alergias

Common anticholinergic drugs like Benadryl linked to increased dementia risk (Harvard Health Blog)

POSTED JANUARY 28, 2015, 8:55 PM

Beverly Merz, Harvard Women’s Health Watch

One long-ago summer, I joined the legion of teens helping harvest our valley’s peach crop in western Colorado. My job was to select the best peaches from a bin, wrap each one in tissue, and pack it into a shipping crate. The peach fuzz that coated every surface of the packing shed made my nose stream and my eyelids swell. When I came home after my first day on the job, my mother was so alarmed she called the family doctor. Soon the druggist was at the door with a vial of Benadryl (diphenhydramine) tablets. The next morning I was back to normal and back on the job. Weeks later, when I collected my pay (including the ½-cent-per-crate bonus for staying until the end of the harvest), I thanked Benadryl.

Today, I’m thankful my need for that drug lasted only a few weeks. A report published online this week in JAMA Internal Medicine offers compelling evidence of a link between long-term use of anticholinergic medications like Benadryl and dementia.

Anticholinergic drugs block the action of acetylcholine. This substance transmits messages in the nervous system. In the brain, acetylcholine is involved in learning and memory. In the rest of the body, it stimulates muscle contractions. Anticholinergic drugs include some antihistamines, tricyclic antidepressants, medications to control overactive bladder, and drugs to relieve the symptoms of Parkinson’s disease.

What the study found

A team led by Shelley Gray, a pharmacist at the University of Washington’s School of Pharmacy, tracked nearly 3,500 men and women ages 65 and older who took part in Adult Changes in Thought (ACT), a long-term study conducted by the University of Washington and Group Health, a Seattle healthcare system. They used Group Health’s pharmacy records to determine all the drugs, both prescription and over-the-counter, that each participant took the 10 years before starting the study. Participants’ health was tracked for an average of seven years. During that time, 800 of the volunteers developed dementia. When the researchers examined the use of anticholinergic drugs, they found that people who used these drugs were more likely to have developed dementia as those who didn’t use them. Moreover, dementia risk increased along with the cumulative dose. Taking an anticholinergic for the equivalent of three years or more was associated with a 54% higher dementia risk than taking the same dose for three months or less.

The ACT results add to mounting evidence that anticholinergics aren’t drugs to take long-term if you want to keep a clear head, and keep your head clear into old age. The body’s production of acetylcholine diminishes with age, so blocking its effects can deliver a double whammy to older people. It’s not surprising that problems with short-term memory, reasoning, and confusion lead the list of anticholinergic side effects, which also include drowsiness, dry mouth, urine retention, and constipation.

The University of Washington study is the first to include nonprescription drugs. It is also the first to eliminate the possibility that people were taking a tricyclic antidepressant to alleviate early symptoms of undiagnosed dementia; the risk associated with bladder medications was just as high.

“This study is another reminder to periodically evaluate all of the drugs you’re taking. Look at each one to determine if it’s really helping,” says Dr. Sarah Berry, a geriatrician and assistant professor of medicine at Harvard Medical School. “For instance, I’ve seen people who have been on anticholinergic medications for bladder control for years and they are completely incontinent. These drugs obviously aren’t helping.”

Many drugs have a stronger effect on older people than younger people. With age, the kidneys and liver clear drugs more slowly, so drug levels in the blood remain higher for a longer time. People also gain fat and lose muscle mass with age, both of which change the way that drugs are distributed to and broken down in body tissues. In addition, older people tend to take more prescription and over-the-counter medications, each of which has the potential to suppress or enhance the effectiveness of the others.

What should you do?

In 2008, Indiana University School of Medicine geriatrician Malaz Boustani developed the anticholinergic cognitive burden scale, which ranks these drugs according to the severity of their effects on the mind. It’s a good idea to steer clear of the drugs with high ACB scores, meaning those with scores of 3. “There are so many alternatives to these drugs,” says Dr. Berry. For example, selective serotonin re-uptake inhibitors (SSRIs) like citalopram (Celexa) or fluoxetine (Prozac) are good alternatives to tricyclic antidepressants. Newer antihistamines such as loratadine (Claritin) can replace diphenhydramine or chlorpheniramine (Chlor-Trimeton). Botox injections and cognitive behavioral training can alleviate urge incontinence.

One of the best ways to make sure you’re taking the most effective drugs is to dump all your medications — prescription and nonprescription — into a bag and bring them to your next appointment with your primary care doctor.

Anúncios

Gut bacteria that protect against food allergies identified (Science Daily)

Date: August 25, 2014

Source: University of Chicago Medical Center

Summary: The presence of Clostridia, a common class of gut bacteria, protects against food allergies, a new study in mice finds. The discovery points toward probiotic therapies for this so-far untreatable condition. Food allergies affect 15 million Americans, including one in 13 children, who live with this potentially life-threatening disease that currently has no cure, researchers note.

Artist’s rendering of bacteria (stock illustration). Credit: © zuki70 / Fotolia

The presence of Clostridia, a common class of gut bacteria, protects against food allergies, a new study in mice finds. By inducing immune responses that prevent food allergens from entering the bloodstream, Clostridia minimize allergen exposure and prevent sensitization — a key step in the development of food allergies. The discovery points toward probiotic therapies for this so-far untreatable condition, report scientists from the University of Chicago, Aug 25 in the Proceedings of the National Academy of Sciences.

Although the causes of food allergy — a sometimes deadly immune response to certain foods — are unknown, studies have hinted that modern hygienic or dietary practices may play a role by disturbing the body’s natural bacterial composition. In recent years, food allergy rates among children have risen sharply — increasing approximately 50 percent between 1997 and 2011 — and studies have shown a correlation to antibiotic and antimicrobial use.

“Environmental stimuli such as antibiotic overuse, high fat diets, caesarean birth, removal of common pathogens and even formula feeding have affected the microbiota with which we’ve co-evolved,” said study senior author Cathryn Nagler, PhD, Bunning Food Allergy Professor at the University of Chicago. “Our results suggest this could contribute to the increasing susceptibility to food allergies.”

To test how gut bacteria affect food allergies, Nagler and her team investigated the response to food allergens in mice. They exposed germ-free mice (born and raised in sterile conditions to have no resident microorganisms) and mice treated with antibiotics as newborns (which significantly reduces gut bacteria) to peanut allergens. Both groups of mice displayed a strong immunological response, producing significantly higher levels of antibodies against peanut allergens than mice with normal gut bacteria.

This sensitization to food allergens could be reversed, however, by reintroducing a mix of Clostridia bacteria back into the mice. Reintroduction of another major group of intestinal bacteria, Bacteroides, failed to alleviate sensitization, indicating that Clostridia have a unique, protective role against food allergens.

Closing the door

To identify this protective mechanism, Nagler and her team studied cellular and molecular immune responses to bacteria in the gut. Genetic analysis revealed that Clostridia caused innate immune cells to produce high levels of interleukin-22 (IL-22), a signaling molecule known to decrease the permeability of the intestinal lining.

Antibiotic-treated mice were either given IL-22 or were colonized with Clostridia. When exposed to peanut allergens, mice in both conditions showed reduced allergen levels in their blood, compared to controls. Allergen levels significantly increased, however, after the mice were given antibodies that neutralized IL-22, indicating that Clostridia-induced IL-22 prevents allergens from entering the bloodstream.

“We’ve identified a bacterial population that protects against food allergen sensitization,” Nagler said. “The first step in getting sensitized to a food allergen is for it to get into your blood and be presented to your immune system. The presence of these bacteria regulates that process.” She cautions, however, that these findings likely apply at a population level, and that the cause-and-effect relationship in individuals requires further study.

While complex and largely undetermined factors such as genetics greatly affect whether individuals develop food allergies and how they manifest, the identification of a bacteria-induced barrier-protective response represents a new paradigm for preventing sensitization to food. Clostridia bacteria are common in humans and represent a clear target for potential therapeutics that prevent or treat food allergies. Nagler and her team are working to develop and test compositions that could be used for probiotic therapy and have filed a provisional patent.

“It’s exciting because we know what the bacteria are; we have a way to intervene,” Nagler said. “There are of course no guarantees, but this is absolutely testable as a therapeutic against a disease for which there’s nothing. As a mom, I can imagine how frightening it must be to worry every time your child takes a bite of food.”

“Food allergies affect 15 million Americans, including one in 13 children, who live with this potentially life-threatening disease that currently has no cure,” said Mary Jane Marchisotto, senior vice president of research at Food Allergy Research & Education. “We have been pleased to support the research that has been conducted by Dr. Nagler and her colleagues at the University of Chicago.”


Journal Reference:

  1. A. T. Stefka, T. Feehley, P. Tripathi, J. Qiu, K. McCoy, S. K. Mazmanian, M. Y. Tjota, G.-Y. Seo, S. Cao, B. R. Theriault, D. A. Antonopoulos, L. Zhou, E. B. Chang, Y.-X. Fu, C. R. Nagler. Commensal bacteria protect against food allergen sensitization. Proceedings of the National Academy of Sciences, 2014; DOI: 10.1073/pnas.1412008111