The mechanisms underlying monogenic intellectual disability (ID) and autism spectrum disorder (ASD), affecting >2% of the population, remain poorly understood. Moreover, most ID/ASD syndromes are still untreatable, the exception being some disorders of metabolic origin. Therefore, identifying unappreciated metabolic mechanisms underlying the pathophysiology of ID/ASD provides a promising avenue to treatment. Several lines of evidence suggest that the transcription factors FOXP1/2/4 are ID/ASD genes with such an underappreciated role in brain (energy) metabolism: mitochondrial defects and altered metabolic rate in FOXP animal models, unpublished FoxP-/- brain transcriptome data of my host, and GWAS-based data indicating that FOXP1/2 genes are significantly associated with body mass index in the general population. Therefore, my main aim is to characterize ID/ASD phenotype-relevant metabolic dysregulation in FoxP mutants and ameliorate its effects. Powerful genetic tools in Drosophila allow me to probe specific molecular mechanisms with high spatial and temporal resolution and relate them to clinically relevant phenotypes, including locomotion behaviour habituation learning, and sleep. My objectives are to: 1) Identify phenotype-relevant metabolic target pathways of FoxP, 2) Characterize metabolic dysregulation in FoxP neurons with spatial resolution 3) Reverse behavioural FoxP phenotypes with metabolic or other innovative therapeutic interventions. This interdisciplinary approach further develops the data analyses, molecular, and imaging skills that I acquired through my PhD training and allows me to merge it with unique disease-relevant data, clinical knowledge, and collaborating networks. This project has the potential to provide novel insights into the relation of metabolism, cognition, and behaviour, and revolutionize the treatment of FOXP1/2/4 disorders. These insights may also have implications for further molecularly and clinically related ID/ASD disorders.