Previous studies have established that prenatal exposure to cigarette smoking is a risk factor for obesity. Results from a cross-sectional study conducted in Canada suggest that this exposure may promote obesity in adolescents by enhancing dietary preference for fat.
“We have shown previously that prenatal exposure to maternal cigarette smoking (PEMCS) enhances accelerated weight gain during late puberty, increasing both whole-body and intra-abdominal adiposity,” the researchers wrote.
Using the ongoing Saguenay Youth Study, Amirreza Haghighi, MD, from The Hospital for Sick Children at the University of Toronto, Canada, and colleagues examined 378 patients aged 13 to 19 years who were recruited through regional high schools. The researchers only included adolescents at Tanner stages 4 and 5 of puberty.
Of the patients included, 180 were exposed and 198 were not exposed to maternal cigarette smoking. Exposure was defined as having a mother who smoked more than one cigarette per day during her second trimester. Unexposed patients were defined as having a mother who did not smoke one year prior to and throughout pregnancy, researchers wrote.
The researchers assessed fat intake with a 24-hour food recall and measured body adiposity with anthropometry and multifrequency bioimpedance. Researchers wrote that they also used MRI to measure the volumes of key brain structures involved in reward processing, including the amygdala, nucleus accumbens and orbitofrontal cortex.
According to data, exposed patients vs. unexposed patients displayed higher total body fat by about 1.7 kg (P=.009) and fat intake by 2.7% (P=.001). Moreover, patients also displayed a lower volume of the amygdala by 95 mm3 (P<.001), but not the other two brain structures, the researchers wrote. Further data indicate amygdala volume had an opposite association with fat intake (r=–0.15; P=.006).
“The results of our study suggest that PEMCS may increase the risk for obesity by enhancing dietary intake of fat, and that this effect may be mediated in part through subtle changes in brain structures involved in reward processing,” the researchers wrote.
Further functional imaging studies in humans and preclinical studies in animals to improve the understanding of how cigarette smoking impacts the amygdala and reward processing of fat intake have been suggested by the researchers.
Disclosure: The researchers report no relevant financial disclosures.