Brain derived neurotrophic factor level indicates childhood obesity risk

By Sally Robertson, B.Sc.Sep 4 2012

Brain derived neurotrophic factor (BDNF) may play an important role in the development and pathophysiology of childhood obesity, report researchers.

In a study of Japanese children aged a mean of 10.3 years, the team found that plasma BDNF levels were significantly lower in morbidly obese children than in obese and nonobese children.

Interestingly, plasma BDNF was associated with the children's birth weight. "This result might suggest that the weight at birth could affect the plasma BDNF levels in obese children," say Shunsuke Araki (University of Occupational and Environmental Health, Kitakyushu, Japan) and colleagues.

Using national statistics for Japanese school children as reference, the team calculated body mass index (BMI), BMI-percentile, and BMI Z-score (a measure of their relative weight adjusted for age and gender) for 66 obese Japanese children and 32 age-matched obese children who underwent assessment of BDNF levels and anthropometric parameters.

As reported in Obesity Research and Clinical Practice, the mean BMI-Z score was significantly higher among the morbidly obese (BMI ≥99^th percentile) children than among those who were obese (≥90^th BMI percentile, <99^th BMI percentile) and nonobese (<90^th percentile), at 3.39, 2.15, and -0.67, respectively.

The mean plasma BDNF level among the morbidly obese children was significantly lower than in the obese and nonobese children, at 507 pg/mL versus 626 pg/mL and 621 pg/mL, respectively.

The researchers also found that 10 of the children were diagnosed with the metabolic syndrome (eight morbidly obese and two obese) and that the mean BDNF level among these children was significantly lower than among children who did not have the metabolic syndrome, at 476 pg/mL versus 611 pg/mL.

As some studies have also shown that a small size for gestational age at birth might be a risk factor for Type 2 diabetes and the metabolic syndrome, the team also assessed the relationship between birth weight and plasma BDNF levels in the obese children.

Among the obese and morbidly obese children the plasma levels of BDNF were positively correlated with birthweight and inversely correlated with BMI-Z score, report Araki et al.

Furthermore, multivariate analysis showed that BMI Z-score and birth weight were independent predictors of the plasma BDNF levels.

"The impact of birth weight on the circulation of BDNF levels in obese individuals needs to be investigated in further studies," says the team.

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