Associação entre o estado nutricional, consumo alimentar e transtorno de déficit de atenção e hiperatividade na infância

Abstract

Attention-Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder that begins in childhood and may persist into adulthood. Its etiology involves both genetic and environmental factors, with dietary patterns and excess weight standing out as relevant influences. Evidence suggests a bidirectional association between ADHD and obesity, indicating that the disorder may both predispose individuals to and result from alterations in nutritional status. Studies also suggest that frequent consumption of ultraprocessed foods exacerbates ADHD symptoms, whereas a balanced diet rich in unprocessed foods may alleviate them. Cortisol, a hormone regulated by the hypothalamic-pituitary-adrenal (HPA) axis, may mediate these associations, as children with ADHD tend to present HPA axis hypoactivity, while obesity and inadequate diets are associated with its hyperactivity. However, longitudinal studies that investigate these relationships in an integrated manner during childhood remain scarce. This dissertation aimed to examine the bidirectionality of the associations between ADHD symptoms, nutritional status, and dietary intake in childhood, as well as to assess the potential mediating role of hair cortisol in the relationship between ADHD and the consumption of ultra-processed foods. Data were drawn from the 2015 Pelotas Birth Cohort, with information collected at 2, 4, and 6–7 years of age. The first article evaluated the relationship between ADHD symptoms and nutritional status using cross-lagged panel models and cross-sectional analyses. It found that ADHD symptoms at age 4 were positively associated with height, and at age 6–7, with greater fat-free mass, weight, height, and BMI. Nevertheless, longitudinal analyses did not show a statistically significant bidirectional relationship between ADHD and BMI. The second article examined the cumulative effects and sensitive periods of dietary intake on ADHD symptoms. Children with consistently high intake of unprocessed foods showed lower ADHD symptoms at age 6–7, while those with high consumption of ultraprocessed foods exhibited higher symptom levels. The ages of 4 and 6–7 were identified as critical windows during which diet exerts a stronger influence on neurological development. The third article investigated the bidirectional relationship between ADHD symptoms and ultra-processed food consumption at ages 4 and 6–7, as well as the potential mediating role of hair cortisol. ADHD symptoms at age 4 were associated with greater consumption of ultra-processed foods at age 6–7 in unadjusted models; however, this association lost statistical significance after adjustment. No association was found in the reverse direction, and hair cortisol did not mediate this relationship. In conclusion, ADHD symptoms were associated with indicators of nutritional status and dietary intake throughout childhood, particularly with increased consumption of ultra-processed foods. The findings did not support hair cortisol as an explanatory mechanism in the relationship between ADHD and ultra-processed food consumption. The findings reinforce the importance of encouraging healthy eating habits from childhood as a strategy to support adequate growth and neurodevelopment.