Who is at risk and why?

Allergies can develop at any age, possibly even in the womb. They commonly occur in children but may give rise to symptoms for the first time in adulthood. Asthma may persist in adults while nasal allergies tend to decline in old age.

Why, you may ask, are some people “sensitive” to certain allergens while most are not? Why do allergic persons produce more IgE than those who are non-allergic? The major distinguishing factor appears to be heredity. For some time, it has been known that allergic conditions tend to cluster in families. Your own risk of developing allergies is related to your parents’ allergy history. If neither parent is allergic, the chance that you will have allergies is about 15%. If one parent is allergic, your risk increases to 30% and if both are allergic, your risk is greater than 60%.

Although you may inherit the tendency to develop allergies, you may never actually have symptoms. You also do not necessarily inherit the same allergies or the same diseases as your parents. It is unclear what determines which substances will trigger a reaction in an allergic person. Additionally, which diseases might develop or how severe the symptoms might be is unknown.

Another major piece of the allergy puzzle is the environment. It is clear that you must have a genetic tendency and be exposed to an allergen in order to develop an allergy. Additionally, the more intense and repetitive the exposure to an allergen and the earlier in life it occurs, the more likely it is that an allergy will develop.

There are other important influences that may conspire to cause allergic conditions. Some of these include smoking, pollution, infection, and hormones.

What are common allergic conditions and their symptoms and signs?

The parts of the body that are prone to react to allergies include the eyes, nose, lungs, skin, and stomach. Although the various allergic diseases may appear different, they all result from an exaggerated immune response to foreign substances in sensitive people. The following brief descriptions will serve as an overview of common allergic disorders.

Hypertension Drugs May Cut Alzheimer’s Risk

By Bill Hendrick
WebMD Health News

Reviewed By Louise Chang, MD

Jan. 12, 2010 — Drugs commonly used to treat high blood pressure and heart disease may reduce the risk of dementia and Alzheimer’s disease, a new study suggests.

Boston University scientists, reporting in the journal BMJ, say a class of high blood pressure drugs called angiotensin receptor blockers is associated with a striking decrease in the risk of occurrence and progression of dementia.

The researchers, using information from a U.S. Department of Health System Veterans Affairs database of more than 5 million people, examined records of more than 800,000 predominantly male patients 65 or older.

The researchers compared the patients in groups that included those using an angiotensin receptor blocker (ARB); those using an ACE inhibitor called lisinopril (Prinivil, Zestril); and those using other blood pressure/heart disease medications (excluding statins).

Angiotensin receptor blockers include candesartan (Atacand), irbesartan (Avapro), losartan (Cozaar), and valsartan (Diovan).

There were no differences in average blood pressure among the three groups.

The patients taking an angiotensin receptor blocker had a 19% lower risk of developing dementia compared to those taking lisinopril and a 24% lower risk compared to use of other blood pressure/heart medications. People taking both an ACE inhibitor and an angiotensin receptor blocker, which both target the angiotensin system, had a 46% lower risk of dementia compared with those taking other medications.

The researchers also studied records of patients who already were suffering from dementia or Alzheimer’s. Those patients taking ARBs, the scientists report, had a lower risk of being admitted to a nursing home or dying. Those taking both an ARB and an ACE inhibitor had a 67% lower chance of being admitted to a nursing home.

The results suggest that ARBs might protect against developing Alzheimer’s disease and dementia, the researchers write.

“For those who already have dementia, use of ARBs might delay deterioration of brain function and help keep patients out of nursing homes,” says Benjamin Wolozin, MD, PhD, professor of pharmacology at Boston University and one of the study researchers. “The study is particularly interesting because we compared the effects of ARBs to other medications used for treating blood pressure or cardiovascular disease.”

The researchers write that they do not know exactly why ARBs might be so beneficial, but they believe the drugs may help prevent and reduce nerve cell injury from stroke or blood vessel damage.

The researchers say they’ve conducted the first large-scale study to investigate whether angiotensin receptor blockers reduce the risk of developing Alzheimer’s or dementia.

The findings of the study are “immense,” write Colleen J. Maxwell, PhD, and David B. Hogan, MD, of the University of Calgary in an accompanying editorial. “About 36 million people worldwide have a form of dementia such as Alzheimer’s disease,” they write. “If survival, prevention or treatment do not improve dramatically, this number could double over the next 20 years.”

However, they add, though the findings of the study are dramatic, further work is needed to verify the results.

‘Longevity’ Gene May Cut Dementia Risk

By Denise Mann
WebMD Health News

Reviewed By Louise Chang, MD

Jan. 12, 2010 — The so-called “longevity gene” may do more than add years to your life. It may also help stave off age-related cognitive decline, and this discovery is paving the way for new drugs to treat Alzheimer’s disease, a study shows.

The longevity gene is a variant of the cholesteryl ester transfer protein (CETP) gene, which was discovered in 2003. This variant has been shown to improve cholesterol levels by increasing HDL “good” cholesterol and regulating the size of cholesterol particles. As a result, it has been linked to longevity and lower heart disease risk, but how or if this variant affects the cognitive decline that is known to occur with aging was not known — until now.

The study is published in the Jan. 13 issue of the Journal of the American Medical Association.

Researchers analyzed the blood of 523 people aged 70 and older with no signs of cognitive decline to see which copy or copies of the CETP gene they carried. People in the study also underwent standard neuropsychological and neurological testing each year from 1994 to 2009 and performed tests to measure memory, attention span, and the time it takes to process and react to a signal (psychomotor speed).

During 4.3 years of follow-up, there were 40 new cases of dementia seen among this group. Those participants who had a specific variation of the CETP gene were less likely to experience a decline in memory and to develop dementia.

“We found that people with two copies of the longevity variant of CETP had slower memory decline and a lower risk for developing dementia and Alzheimer’s disease,” says study researcher Amy E. Sanders, MD, assistant professor in the Saul R. Korey Department of Neurology at the Albert Einstein College of Medicine in the Bronx, N.Y., in a news release.

“More specifically,” she says, “those participants who carried two copies of the favorable CETP variant had a 70 percent reduction in their risk for developing Alzheimer’s disease compared with participants who carried no copies of this gene variant.”

This variant alters the gene so that the protein it encodes for will functions less efficiently than usual, the researchers explain. Now, drugs are now being developed that mimic this effect.

“These agents should be tested for their ability to promote successful aging and prevent Alzheimer’s disease,” says study researcher Richard B. Lipton, MD, the Lotti and Bernard Benson Faculty Scholar in Alzheimer’s Disease and professor and vice chairman in the Saul R. Korey Department of Neurology at Albert Einstein College of Medicine, in a news release.