This invention relates to benzodiazepine derivatives, compositions comprising therapeutically effective amounts of those benzodiazepine derivatives and methods of using those derivatives or compositions in treating cognitive impairment associated with central nervous system (CNS) disorders. In particular, it relates to the use of a α5-containing GABAA receptor agonist (e.g., a α5-C containing GABAA receptor positive allosteric modulator) as described herein in treating cognitive impairment associated with central nervous system (CNS) disorders in a subject in need or at risk thereof, including, without limitation, subjects having or at risk for age-related cognitive impairment, Mild Cognitive Impairment (MCI), amnestic MCI (aMCI), Age-Associated Memory Impairment (AAMI), Age Related Cognitive Decline (ARCD), dementia, Alzheimer's Disease (AD), prodromal AD, post traumatic stress disorder (PTSD), schizophrenia, bipolar disorder, amyotrophic lateral sclerosis (ALS), cancer-therapy-related cognitive impairment, mental retardation, Parkinson's disease (PD), autism spectrum disorders, fragile X disorder, Rett syndrome, compulsive behavior, and substance addiction. It also relates to the use of a α5-containing GABAA receptor agonist (e.g., a α5-containing GABAA receptor positive allosteric modulator) as described herein in treating brain cancers (including brain tumors, e.g., medulloblastomas), and cognitive impairment associated therewith.