Daily physical activity is associated with reduced risk for Alzheimer disease (AD) among elders, a new study shows. Roughly 700 adults (average age, 82) free of dementia wore actigraphs on their wrists 24 hours a day for up to 10 days to measure their daily physical activity. During a mean 3.5-year follow-up, 10% were diagnosed with AD. Participants in the lowest decile of physical activity had more than twice the AD as those in the highest decile. The results remained significant after adjustment for self-reported physical, social, and cognitive activities and for performance on motor function tests. More physical activity on actigraphy was also associated with less cognitive decline.

Editorialists conclude, "In a world that is becoming progressively sedentary, and in the context of very limited success of the currently available medications to treat or delay AD, physical activity provides a promising, low-cost, easily accessible, and side-effect-free means to prevent AD."

Comment: This study adds to the growing body of literature emphasizing the importance of physical exercise in maintaining brain health. It is unique in its prospective approach and departure from standard self-report measures of physical activity. Novel findings worth emphasis and future investigation include the advanced age of the participants and the impact of both exercise and nonexercise physical activity, even in the context of restricted mobility. Although asking participants to wear the actigraph may have introduced a confound, if these results are reproducible in other populations, then it may be worth the investment to motivate patients and to routinely assess activity levels as a preventive health initiative. At a minimum, these findings suggest that the time is upon us to engage in a "no excuses!" approach to physical activity advocacy in the clinical setting.

The Higher the Body-Mass Index, the Higher the Risk for Adenoma

A 5-unit increase in BMI was associated with a 19% increased risk for colorectal adenoma.

Obesity is considered a risk factor for colon cancer and adenomas. However, study results have been mixed on the magnitude of risk and whether it is limited to men. Now, researchers have conducted a meta-analysis to clarify the link between body-mass index (BMI) and colorectal adenoma.

Investigators identified 36 studies (16 case-control, 13 cross-sectional, and 7 cohort or nested case-control) appropriate for the meta-analysis. A 5-unit increase in body-mass index (BMI) was associated with a 19% increased risk for colorectal adenoma regardless of patient sex, study region (U.S., Europe, or Asia), or adjustment for physical activity, smoking, caloric intake, alcohol use, and nonsteroidal anti-inflammatory drug use in a subset of studies. In a meta-analysis based on BMI categories, obese patients (BMI 30) but not overweight patients (BMI 25 and <30) had an increased risk for colorectal adenoma compared with patients with normal BMI (<25). A subanalysis of 11 studies found that increased BMI was associated with increased risk for colon adenoma but not rectal adenoma.

Comment: This study firms up the association between body-mass index and colon adenomas. Increased BMI has also been linked with increased risk for cancer of the colon but not the rectum. Current guidelines do not recommend adjustment of screening or surveillance intervals based on BMI.

Cardiovascular disease remains the number-one killer in the U.S. Therefore, the American Heart Association has challenged the American public to improve cardiovascular health by (1) not smoking; (2) being physically active; achieving normal (3) blood pressure, (4) blood glucose and (5) total cholesterol levels, and (6) weight; and (7) eating a healthy diet. To examine trends in cardiovascular health, as related to all-cause and cardiovascular mortality risk, investigators studied National Health and Nutrition Examination Survey (NHANES) data from 1988–1994, 1999–2004, and 2005–2010, and from the NHANES III Linked Mortality File (through 2006).

Of nearly 45,000 participants, very few met all seven cardiovascular health goals (1988–1994, 2.0%; 2005–2010, 1.2%). Absolute mortality risks were significantly lower in participants meeting six or more goals than in those meeting one or fewer goals.  

Comment: Not unexpectedly, according to this large study, the more cardiovascular health goals we meet, the lower our risks for all-cause and cardiovascular mortality. Unfortunately — but also unsurprisingly — few Americans meet these goals. Importantly, the investigators did not study how changes in individuals' cardiovascular health profiles affect risk.