Criteria: Inclusion Criteria:  Patients must receive a Diagnostic and Statistical Manual of Mental Disorders (DSM-5) oriented diagnosis of ADHD and need drug treatment for the severity of symptoms; Intelligent Quotient (IQ) > 85;  Exclusion Criteria:  Presence of Autism Spectrum Disorders; Presence of Mood Disorders; Previous/current diagnosis of neurological conditions (i.e. epilepsy, neurodegenerative diseases); Presence of Genetic Syndromes; Presence of basal medical conditions (i.e. heart, kidney or liver diseases) which may exclude the possibility to administer MPH.