Attention Deficit Hyperactivity Disorder (ADHD) and Polyphenols: A Systematic Review

Polyphenols are natural compounds also contained in daily consumed foods that show their efficacy in different clinical fields. Both pre-clinical and clinical studies demonstrated that polyphenols may manage neuroinflammation and oxidative stress processes tightly connected to neurodegenerative diseases and mental disorders. Thus, a neuroinflammatory state may influence the neurotransmitters pathways, such as the noradrenergic, glutamatergic, serotoninergic, and, in particular, dopaminergic ones, whose impairment is strongly associated with attention deficit hyperactivity disorder (ADHD). Therefore, the aim of the present systematic review is to provide an overview of the clinical outcomes' changes following ADHD treatment with polyphenols alone and in combination with the traditional drugs. This review was conducted according to PRISMA guidelines and recorded on PROSPERO with the number CRD42023438491; PubMed, Scopus, and Web of Science were used as search-engines to lead our research until June 2023. The inclusion criteria were articles written in English, including clinical, placebo-controlled, and case-control trials. We excluded reviews, metanalyses, background articles, and papers published in other languages. To avoid any bias, Rayyan software (COPYRIGHT (c) 2022 RAYYAN) was used to organize the work and manage the literature review. After screening, 10 studies were included, with a total of 556 patients that met the established inclusion criteria. The data obtained from these studies showed that polyphenols rebalanced oxidative stress pathways through different mechanisms, are effective for the treatment of ADHD both alone and in combination with traditional drugs, and are able to reduce symptoms as well as the side effects related to the use of conventional therapies. Finally, a positive effect of using polyphenols for ADHD prevention could be hypothesized.