Background: Down syndrome (DS) is the most common genetic cause of intellectual disability.Although progress in managing co-morbidities has improved life expectancy, no therapeutic options have showed to significantly improve intellectual deficiencies.The current focus of the pharmacological treatment of DS is on the improvement of the cognitive impairment that is probably due to neurodevelopmental alterations,neurotransmitter alterations and neurodegeneration,and is also targeted to the overexpression of selected genes on HSA21. Methods: We review the clinical trials of the last 5 years focusing on the cognitive improvement of children with DS. Results: We report the results of therapeutic trials concerning selective negative allosteric regulators of the GABAAa5 receptor, NMDA antagonists, Kinase inhibitors of DYRK1A, folinic acid and thyroid hormone supplementation, activators of serotonergic and cholinergic system. Conclusions: The incomplete understanding of individual phenotypic variability, natural history, lack of biomarkers, no adapted neuropsychological tests, placebo effect, epigenetic effect have limited our capacity to succeed, even when promising drugs are tested.We need new tools and models will allow a better understanding of the pathophysiology. We also need to create more sensitive and realistic outcome mesures to quantify disease and therapeutic efficacy. The association of different therapeutic agents (epidrugs included) with cognitive stimulation could be a future strategy.