Introduction: Attention deficit hyperactivity disorder (ADHD) has a complex aetiology, mainly attributed to a number of susceptibility genes and environmental factors. Genetic association studies, however, have been inconsistent and have identified genetic variants with a moderate effect that explain a small proportion of the estimated inheritability of the disorder (< 10%). Recent studies suggest that the gut microbiota and diet play an important role in the development and symptoms of different mental disorders. Nevertheless, no clear evidence exists on the issue. This project proposes an alternative approach to identify mechanisms by which the intestinal microbial ecosystem and diet could contribute to the presence of ADHD.
Aim: To identify biomarkers for ADHD by examining the gut microbiota.
Subjects and methods: We conducted a cross-sectional study of adult patients with ADHD (n = 100) and control subjects (n = 100). Measures of ADHD evaluation and eating habits were performed in both groups. Samples of faecal material were obtained from which to extract bacterial DNA, then used to characterise the participants' gut microbiota. A meta-genomic association study was later performed to attempt to correlate the bacterial composition of the intestine with the clinical subtypes of the disorder.
Results and conclusions: Comparing the gut microbiota profiles of subjects with ADHD and controls is expected to help account for the clinical heterogeneity of the disorder and identify new mechanisms involved in its development.
Title: El eje intestino-cerebro en el trastorno por deficit de atencion/hiperactividad: papel de la microbiota.
Introduccion. El trastorno por deficit de atencion/hiperactividad (TDAH) presenta una etiologia compleja, atribuida principalmente a multiples genes de susceptibilidad y factores ambientales. No obstante, los estudios geneticos de asociacion han sido inconsistentes, identificando variantes geneticas de efecto moderado que explican una pequeña proporcion de la heredabilidad estimada del trastorno (< 10%). Recientes estudios sugieren que la microbiota intestinal y la dieta desempeñan un papel importante en el desarrollo y los sintomas de diferentes trastornos mentales. Sin embargo, en la actualidad no existe una claridad absoluta al respecto. El presente proyecto propone un abordaje alternativo para identificar mecanismos a traves de los cuales el ecosistema microbiano intestinal y la dieta podrian contribuir a la presencia del TDAH. Objetivo. Identificar biomarcadores para el TDAH a traves del estudio de la microbiota intestinal. Sujetos y metodos. Estudio transversal de pacientes adultos con TDAH (n = 100) y de individuos control (n = 100). En ambos grupos se tomaran medidas de evaluacion de TDAH y habitos alimentarios. Se obtendran muestras fecales para la extraccion del ADN bacteriano, que permitiran caracterizar la microbiota intestinal de los participantes, para posteriormente realizar un estudio de asociacion metagenomico e intentar correlacionar la composicion bacteriana intestinal con subtipos clinicos del trastorno. Resultados y conclusiones. Se espera que la comparacion de los perfiles de microbiota intestinal entre sujetos con TDAH y controles ayude a explicar la heterogeneidad clinica del trastorno e identificar nuevos mecanismos implicados en su desarrollo.