The Neurocognitive Phenotype of Excess Weight in Adolescents and Young Adults: Biological, Genetic, and Psychosocial Factors

Programa de Doctorat en Medicina i Investigació Traslacional [eng] INTRODUCTION: Excess weight is a complex health condition that is associated with the development of (multi)morbidity. The fact that adolescents with excess weight have a five- fold increased risk of maintaining this condition as adults highlights the need to study which factors favor its emergence and chronicity. The neurocognitive phenotype of excess weight could be referred to as the psychological and brain characteristics that represent a vulnerability to engage in behaviors that promote excess weight. Studying the correlates of this neurocognitive phenotype would help identify individuals at risk of developing excess weight and to propose specific interventions. HYPOTHESES: This thesis approaches excess weight beyond adiposity and targets biological, genetic, and psychosocial factors to study the neurocognitive phenotype of excess weight in adolescents and young adults. Consequently, the hypotheses of this thesis are threefold. First, excess weight and the A allele of the fat mass and obesity-related gene rs9939609 may be associated with lower structural connectivity in the reward network. Second, cardiometabolic factors usually present in excess weight may be associated with increased impulsivity and alterations in white matter microstructure. Third, stress, either led or followed by exposure to adverse childhood experiences or allostatic load, may be associated with poorer executive functioning. OBJECTIVES: In the first study, we aimed to investigate the structural connectivity patterns in the reward network according to body mass index and the genetic risk of obesity assessed by the A allele of the fat mass and obesity-related gene rs99396309. In the second study, we evaluated the association between cardiometabolic factors and both impulsivity and microstructural changes in white matter tracts typically associated with excess weight and impulsivity. In the third study, we examined whether executive functioning was vulnerable to physiological (allostatic load) and psychological stress (adverse childhood experiences). [cat] INTRODUCCIÓ: L'excés de pes és una condició de salut complexa que s'associa amb el desenvolupament de (multi)morbiditat. El fet que els adolescents amb excés de pes tinguin cinc vegades més risc de mantenir aquesta condició en l'edat adulta posa de manifest la necessitat d'estudiar quins factors afavoreixen la seva aparició i cronicitat. El fenotip neurocognitiu d