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Up Front | Apr 2014

Medical Updates

Common Infections May Increase Risk for Memory Decline

Exposure to common infections may be linked to memory and brain function, according to research presented at the American Heart Association's International Stroke Conference 2014 and reported in a news release.1

Clinton Wright, MD, MS, of the Evelyn F. McKnight Brain Institute at the University of Miami, and colleagues conducted brain function tests and took blood samples from 588 patients. Half of the patients then took cognitive tests 5 years later to determine whether past exposure to infections contributed to performance on tests of memory, thinking speed, and other brain functions.

The investigators found that an index of antibody levels caused by exposure to Chlamydophila pneumoniae, Helicobacter pylori, cytomegalovirus, and herpes simplex viruses 1 and 2 was associated with worse cognitive performance including memory, speed of mental processing, abstract thinking, planning, and reasoning ability. They believe exposure to the infections may be associated with an increase in stroke risk, atherosclerosis, and inflammation, according to the news release.

Although the study does not explain why the infections may be related to worsened cognitive function, Dr. Wright said that it may be an immune system response to the infections or that the infection itself could result in clinical damage. “There is no evidence yet that treating these infections is beneficial,” he said in the news release.

  1. 1. Common infections may increase risk for memory decline [news release]. February 13, 2014. http://newsroom. heart.org/news/common-infections-may-increase-risk-for-memory-decline Accessed February 17, 2014.

Mammography May Not Improve Breast Cancer Survival

Annual mammography failed to reduce mortality due to breast cancer, according to follow-up data from the Canadian National Breast Screening Study.1

Anthony B. Miller, MD, of Dalla Lana School of Public Health, University of Toronto, and colleagues conducted a study of 89,835 women aged 40 to 59 years who were randomly assigned to mammography or control (no mammography). Women aged 40 to 49 years in the mammography arm and all women aged 50 to 59 years in both arms received annual physical breast examinations. Women aged 40 to 49 years in the control arm received a single examination followed by usual care.

During the 5-year screening, 666 invasive breast cancers were diagnosed in the mammography arm (n=44,925) and 524 in the control arm (n=44,910). Of these, 180 women in the mammography arm and 171 in the control arm died of breast cancer during the 25-year follow-up.

The study authors concluded that women between the ages of 40 and 59 who received annual mammography for 5 years had a breast cancer mortality hazard of 1.05 (95% CI, 0.85–1.30) compared with women in the same age group who received physical examination. During a mean follow-up of 22 years, the group that received mammography had a breast cancer mortality hazard of 0.99 (95% CI, 0.88–1.12) compared with the group that received physical examination.

“Overall, 22% of screen-detected invasive breast cancers were over-diagnosed, representing one over-diagnosed breast cancer for every 424 women who received mammography screening in the trial,” the study authors concluded.

  1. Miller AB, Wall C, Baines CJ, Sun P, To T, Narod SA. Twenty-five year follow-up for breast cancer incidence and mortality of the Canadian National Breast Screening Study: randomised screening trial. BMJ. 2014;348:g366. doi:10.1136/bmj.g366.

Prescription Testosterone Associated With Increased Risk of Myocardial Infarction in Men

Prescription testosterone therapy increased the rate of myocardial infarction (MI) in men older than 65 years and in men younger than 65 years who had preexisting diagnosed heart disease, according to a study in PLoS One. 1

William D. Finkle, of Consolidated Research, and colleagues conducted a cohort study of the risk of acute, nonfatal MI following an initial testosterone therapy prescription (n=55,593) in a large health care database. The investigators compared the rate of MI during the year prior to prescription and the 90 days following prescription.

Men over age 65 years who received a prescription for testosterone therapy had a twofold increase in MI rate (post/pre ratio rate, 2.19) regardless of cardiovascular disease history. Men under 65 with a history of heart disease had a nearly threefold increase (post/pre ratio rate, 2.90) in MI incidence. The researchers reported no excess risk of MI in men under 65 without a history of heart disease (post/pre ratio rate, 1.17).

The study also examined MI incidence rate in 167,279 men who received prescriptions for phosphodiesterase type 5 inhibitors (sildenafil or tadalafil). The study found no increase in MI among men 65 or older, men under 65 with a history of heart disease, or men under 65 without a history of heart disease (overall post/pre rate ratio, 1.08).

“Given the rapidly increasing use of [testosterone therapy], the current results, along with other recent findings, emphasize the urgency of the previous call for clinical trials adequately powered to assess the range of benefits and risks suggested for such therapy,” the study authors wrote. “Until that time, clinicians might be well advised to include serious cardiovascular events in their discussions with patients of potential risks, particularly for men with existing cardiovascular disease.”

  1. Finkle WD, Greenland S, Ridgeway GK, et al. Increased risk of non-fatal myocardial infarction following testosterone therapy prescription in men [published online ahead of print January 29, 2014]. PLoS One. doi:10/1371/journal.pone.0085805.

Low-Range Hypertension May Increase Stroke Risk

Even slightly elevated blood pressure may be associated with an increased risk of stroke, according to a meta-analysis published in Neurology.1

Yuli Huang, MD, of Southern Medical University in Guangzhou, China, and colleagues searched PubMed and Embase databases for studies with data on prehypertension and stroke. Prospective studies were included if they reported multivariate-adjusted relative risks (RRs) with 95% CIs for the association between stroke and prehypertension or its two subranges (low-range prehypertension: 120–129/80–84 mm Hg; high-range prehypertension: 120–129/85–89 mm Hg). Subgroup analyses were conducted according to blood pressure ranges, stroke type, endpoint, age, sex, ethnicity, and study characteristics.

Pooled data included the results of 762,393 patients from 19 prospective cohort studies. Prehypertension increased the risk of stroke (RR, 1.66; 95% CI, 1.51–1.81) compared with optimal blood pressure (<120/80 mm Hg). In the secondary outcomes analyses, even low-range prehypertension increased the risk of stroke (RR, 1.44; 95% CI, 1.27–1.63). The risk was greater for high-range prehypertension (RR, 1.95; 95% CI, 1.73–2.21). The RR was higher with high-range than with low-range prehypertension (P <.001). There were no significant differences in any of the subgroup analyses.

“After adjusting for multiple cardiovascular risk factors, prehypertension is associated with stroke morbidity,” the study authors concluded.

  1. Huang Y, Cai X, Li Y, et al. Prehypertension and stroke risk [published online ahead of print March 12, 2014]. Neurology. doi:10.1212/WNL.0000000000000268.

–Compiled by Callan Navitsky, Senior Editor