Lab Notes

MRI Scans Offer Clues for People at Genetic Risk for Alzheimer’s

People at high risk for Alzheimer’s disease develop abnormal brain function even before the appearance of telltale amyloid, the protein that makes up the senile plaques that dot the brains of Alzheimer’s patients. Researchers at Washington University School of Medicine, led by Dr. Yvette Sheline, found that these patients had a particular form of a gene called APOE4. The research team conducted MRI scans on 100 people whose average age was 62. About half of them carried the APOE4 variant, which is a genetic risk factor for late-onset Alzheimer’s. The goal of the study is to identify those with the highest risk of Alzheimer’s and to develop treatments that interfere with the progression of the disease, keeping it from advancing to the stage when amyloid begins to build up in the brain and, eventually, dementia sets in. “The current belief is that from the time excess amyloid begins to collect in the brain, it takes about 10 years for a person to develop dementia,” Sheline says. “But this new study would suggest we might be able to intervene even before amyloid plaques begin to form. That could give us an even longer time window to intervene once an effective treatment can be developed.”

Growth Hormone Not the Answer for Longevity

A compound that acts in the opposite way as growth hormone can reverse some of the signs of aging, according to a recent Saint Louis University School of Medicine study. The finding may be counter-intuitive to some older adults who take growth hormone, thinking it will help revitalize them. In a study of mice engineered for studies of the aging process, the researchers found that MZ-5-156 had positive effects on oxidative stress in the brain, improving cognition, telomerase activity (the actions of an enzyme that protects DNA material) and life span, while decreasing tumor activity.

MZ-5-156, like many GHRH antagonists, inhibited several human cancers, including prostate, breast, brain and lung cancers. It also had positive effects on learning, and is linked to improvements in short-term memory. The findings are significant, says study co-investigator Dr. John E. Morley. “Many older people have been taking growth hormone to rejuvenate themselves,” Morley says. “These results strongly suggest that growth hormone, when given to middle-aged and older people, may be hazardous.”

Children with Mild Asthma May Benefit from Intermittent Treatment

Children who have asthma but are experiencing few or no symptoms often stop using daily asthma medications, much to their doctors’ chagrin. However, results of a new study suggest taking medication at the onset of symptoms is better than taking nothing at all. Researchers at Washington University School of Medicine and four other U.S. medical centers found that children with asthma who discontinued daily therapy could still get good results in controlling mild asthma by using a rescue inhaler (albuterol) followed by a low-dose inhaled corticosteroid only when they were having symptoms. “While standard treatment was still more effective in preventing symptoms, this alternative is preferable to discontinuing the medication entirely,” says Dr. Robert Strunk, Washington University professor of pediatrics. “This is the first study in which low-dose inhaled corticosteroids were used at the same time as a rescue inhaler, together with albuterol, in school-age children. Between 7 percent and 12 percent of children have asthma, which is the No. 1 cause of hospitalizations in children.

‘Healthy’ Patients at High Risk of Cardiac Death Identified

The way the heart responds to an early beat is predictive of cardiac death, especially for people with no conventional markers of cardiovascular disease, according to new research from Washington University School of Medicine. Conventional risk factors, such as high cholesterol, smoking, diabetes and high blood pressure, account for many but not all deaths from cardiovascular causes. New research indicates that an abnormal response to an early beat in the left ventricle, the heart’s main pumping chamber, can identify high-risk patients even when they have no other evidence of cardiovascular disease. A ventricular premature beat (VPB) occurs when the ventricle gets an inappropriate signal, causing it to beat before it should. VPBs are common, even in healthy people. ”These are people we do not expect to die of cardiac causes,” says Dr. Phyllis K. Stein, director of the Heart Rate Variability Laboratory at the School of Medicine. “They appear healthy, but they’re not. We have shown a way they’re not healthy that isn’t showing up using standard tests.” The question is not whether VPBs occur, but how the body responds to them. The heart’s response, called heart rate turbulence, can be measured with a Holter monitor, a device worn for 24 hours that records the electrical signals produced by the heart.