Some smokers have more of an urge to light up right after they wake up, and researchers have identified a reason: variation in a substance that breaks down nicotine in the brain. Smokers with genes that produce more of the enzyme FMO3, which metabolizes nicotine in the brain, were more likely to smoke first thing in the morning — a key indicator of nicotine dependence. The new understanding could someday allow researchers to individualize tobacco cessation treatments.

Can your ‘good’ cholesterol be too high?

High levels of high-density lipoprotein, or “good” cholesterol, are generally considered healthy. But can you have too much of a good thing? Possibly, a study in the European Heart Journal found. In the study, Danish researchers found that an HDL of 73 milligrams per deciliter in men and 93 in women was associated with the lowest all-cause mortality. Compared with that, men with HDL levels of 97 to 115 had a 36 percent increased risk for death, and twice the risk above 116. Women at greater than 135 had a 68 percent increased risk.

Prostate screening may save lives after all

After years of doubt about the value of screening men for prostate cancer, a new analysis of existing clinical trial evidence has found that when men between 55 and 70 get the prostate-specific antigen, or PSA, test, the result is lives saved. The new research concluded that screening men over age 55 “can significantly reduce the risk for prostate cancer death.” That reduction was between 25 percent and 32 percent, the study found.

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