Carotid arteries are in the neck and supply blood to the brain. Thickening of the carotid artery wall is an early sign of atherosclerotic disease and a risk factor for stroke.
The association between obesity – regardless of other risk factors, such as high blood pressure – and atherosclerotic disease has been controversial, says the study's author Paolo Rubba, M.D., professor of internal medicine and director of the clinical unit for vascular medicine Federico II University, Naples, Italy.
"There is an established link between obesity and damage to the heart, but whether obesity also has an independent effect on the carotid arteries is less well known," he says.
Researchers investigated whether overall obesity and obesity specific to the abdominal area were associated with thickening of the carotid arteries. They analyzed data from the Progetto ATENA study, an ongoing study of chronic disease in more than 5,000 middle-aged women from Southern Italy. In this region, increased caloric intake, increased animal fat intake and sedentary habits have led to a high prevalence of overweight and obesity, the researchers say.
Researchers took a sub-sample of 310 study participants (average age 55) who had ultrasound testing to examine the intima-media thickness (IMT), which is the lining and middle muscle layers of the carotid artery. They also examined the intima-media area (IM). The researchers compared body mass index (BMI) and waist-to-hip ratio – which both indicate obesity – to the health of the carotid arteries.
They found a significant association between the estimates of obesity and the level of wall thickness, which was still significant after accounting for other risk factors, such as age, blood pressure and cholesterol.
Women with BMI of 30 kilograms per meter squared (kg/m2) or greater had higher blood pressure, triglycerides, glucose, and insulin and lower high-density lipoprotein (HDL, the "good" cholesterol.)
A gradual increase in IMT was found with increasing weight. Lean women (23.0 BMI) had an average IMT of 0.94 millimeters (mm), overweight women (27.2 BMI) had an average of 0.98 mm and obese women (33.8 BMI) had an average of 1.02 mm. IM was 20 mm for lean women, 21 for overweight women and 23 for obese women.
Women with high waist-to-hip ratios also had higher triglycerides, glucose and insulin and decreased HDL. The wall thickness measurements were higher for women with higher waist- to-hip ratios.
Hence, BMI and waist-to-hip ratio were significant predictors of carotid wall thickness, independent of other risk factors. Researchers conclude that general and abdominal obesity are associated with carotid artery wall thickening in middle-aged women.
"Controlling blood pressure is not enough to prevent the cardiovascular damage from being overweight," Rubba says. "Doctors should face the difficult challenge of encouraging patients to lose weight to prevent premature atherosclerosis and stroke. With the information in this study, women also should be aware of further health implications if they don't reduce their weight."
The study suggests that ultrasound screening in obese women may help identify those at high risk and those who may require aggressive therapy to prevent early atherosclerosis, he says. By seeing the early warning signs, women and their doctors might be better motivated to aggressively treat obesity and the benefits of their efforts might be evident in follow-up evaluations years later.
Future studies should focus on whether atherosclerosis in obese women progresses faster than in women who are not obese, Rubba says.
Co-authors are Mario De Michele, M.D.; Salvatore Panico, M.D.; Arcangelo Iannuzzi, M.D.; Egidio Celentano, M.D.; Anna V. Ciardullo, M.D.; Rocco Galasso, M.D.; Lucia Sacchetti, Ph.D.; Federica Zarrilli, Ph.D.; and M. Gene Bond, Ph.D.
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