The present invention is concerned with deuterium-enriched isobutyl and cyclohexylmethyl sulfonamides of formula I and II, and pharmaceutically acceptable salts and methods of use thereof for the treatment of general anxiety disorders, major depressive disorders, attention deficit disorders, attention deficit hyperactivity disorder, Alzheimer's disease, frontotemporal dementia, cognitive impairment associated with age-related dementia, schizophrenia, migraine, sleep disorders, neurodegenerative diseases and obesity.