Your health: High BMI increases diabetes risk, but not heart attacks
High BMI increases diabetes risk
Being overweight is less likely to cause a heart attack or kill you than it is to increase your risk of diabetes, according to a new study of identical twins, the American Heart Association News reports.
Researchers used a nationwide Swedish twin registry to find twin pairs with identical DNA but different body mass indexes, or BMIs. While conventional medical wisdom has long suggested that heavier people are more likely to have premature heart attacks than lean people, the new study suggests otherwise.
The research, published online recently by JAMA Internal Medicine, followed more than 4,000 genetically identical twin pairs with differing BMIs from March 1998 to January 2003, and followed up with them through 2013. The study compared the risk of heart attack, death and Type 2 diabetes.
“The fatter twin actually had a lower risk of myocardial infarction (heart attack) or death, although the risk of diabetes was higher,” said the lead researcher of the study, Peter Nordström, Ph.D., of the Umea University in Sweden.
“After adjusting for genetic factors, obesity does not seem to be associated with cardiovascular disease or death, at least not to an increased risk,” Nordström said.
The study reported 203 heart attacks (5 percent) and 550 deaths (13.6 percent) among the heavier twins, who had an average BMI of 25.9. But the leaner twins, with an average BMI of 23.9, had slightly higher numbers, with 209 heart attacks (5.2 percent) and 633 deaths (15.6 percent).
Even twins who had a BMI of 30 or higher — the threshold to be considered obese — still didn't have a greater risk of heart attack or death than the leaner twin.
Yet when it came to Type 2 diabetes, the heavier twins did have a greater risk, leading investigators to conclude “lifestyle interventions to reduce obesity may be more effective in reducing the risk of diabetes than the risk of cardiovascular disease or death.”
“This study has important clinical implications,” wrote Dr. David J. Davidson, of NorthShore University HealthSystem, and the University of Chicago's Dr. Michael H. Davidson in an editorial accompanying the study. “The findings confirm the causal link between obesity and diabetes, which is a growing epidemic throughout the world. Therefore, weight reduction should remain the cornerstone for the prevention of diabetes.”
Even so, they wrote, the study has some important limitations. Waist size — a better indicator of whether someone is “metabolically obese” despite having a normal BMI — was not measured, and the 12-year follow-up period may not have been long enough for the higher diabetes rate among the heavier twins to result in more cases of heart disease.
Study looks at genes affecting depression
In a key advance for the study of depression, a comprehensive scan of human DNA has turned up the apparent hiding places of more than a dozen genes linked to the disorder, The Associated Press reports.
“This is a jumping-off point” for further work to reveal the biological underpinnings of depression, which in turn can guide development of new drugs, said Ashley Winslow, an author of a paper on the work.
Experts said the result is important not only for its specific findings, but also for its demonstration that the study's approach can help uncover clues to the biology of depression, which is largely a mystery.
The work by Winslow and others identified 15 areas of the human DNA — the “genome” — that show signs of harboring genetic variations that affect risk of becoming depressed. That indicates where scientists can focus on identifying and studying the affected genes, which in turn could reveal what processes go awry to raise the risk of the disease.