Hippocampal atrophy and altered brain responses to pleasant tastes among obese compared with healthy weight children

OBJECTIVE: The hippocampus is a key structure implicated in food motivation and intake. Research has shown that the hippocampus is vulnerable to the consumption of a western diet (i.e., high saturated fat and simple carbohydrates). Studies of patients with obesity (OB), compared with healthy weight (HW), show changes in hippocampal volume and response to food cues. Moreover, evidence suggests that OB children, relative to HW, have greater hippocampal response to taste. However, no study has examined the association of hippocampal volume with taste functioning in children. We hypothesized that OB children, relative to HW, would show a significant reduction in hippocampal volume and that decreased volume would be significantly associated with greater activation to taste. Finally, we explored whether hippocampal activation would be associated with measures on eating and eating habits. SUBJECTS: Twenty-five 8-12-year-old children (i.e., 13 HW, 12 OB) completed a magnetic resonance imaging scan while participating in a taste paradigm (i.e., 1 ml of 10% sucrose or ionic water delivered pseudorandomly every 20 s). RESULTS: Children with OB, relative to HW, showed reduced left hippocampal volume (t = 1.994, P = 0.03, 95% confidence interval (CI) = -40.23, 755.42), and greater response to taste in three clusters within the left hippocampus (z = 3.3, P = 0.001, 95% CI = -0.241, -0.041; z = 3.3, P = 0.001, 95% CI = -0.2711, -0.0469; z = 2.7, P = 0.007, 95% CI = -0.6032, -0.0268). Activation within the hippocampus was associated with eating in the absence of hunger (EAH%; t = 2.408, P = 0.025, 95% CI = 1.751708, 23.94109) and two subscales on a measure of eating behaviors (Food responsiveness, t = 2.572, P= 0.017, 95% CI = 0.9565195, 9.043440; Food enjoyment, t = 2.298, P = 0.032, 95% CI = 0.2256749, 4.531298). CONCLUSION: As hypothesized, OB children, relative to HW, had significantly reduced hippocampal volume, and greater hippocampal activation to taste. Moreover, hippocampal activation was associated with measures of eating. These results contribute to research on the relationship between OB, overeating and cognitive impairment.