Effects of 800mg of Rhodiola Rosea in Attention in Adults With Attention-Deficit/Hyperactivity Disorder

Inclusion Criteria: * Fulfillment of Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, (DSM-5) diagnostic criteria for ADHD in Adults * Intelligence Quotient (IQ) above 70 * Eligibility to Rhodiola rosea Exclusion Criteria: * clinical contraindication to Rhodiola rosea * any unstable chronic illness without proper treatment (hypertension, heart, kidney or liver disease, etc) * any significant neurological disease (delirium, dementia, epilepsy, AIDS, head trauma, multiple sclerosis, stroke, etc) * unstable psychiatric comorbidities requiring immediate treatment (risk of suicide, current Substance Use Disorder, etc.) * pregnant, nursing or absence of reliable contraception * current use of nicotine (\<30 days) * use of anticoagulants * current use of any psychoactive drug (\<30 days) * prior use of stimulants * current or lifetime psychosis * current or lifetime bipolar disorder