Khat Catha edulis Forsk, qat, kat, chat Khat is a stimulant drug, which means it speeds up the messages going between the brain and the body. The drug is the leaves and buds of the khat plant. Source: Alcohol and Drug Foundation Related content Betel nut The areca nut, commonly referred to as betel nut, is the seed of the fruit of the areca palm. Kava Kava is a depressant drug, which means it slows down the messages travelling between the brain and the body. Quick guide to drugs & alcohol An easy to read reference book with information on a range of drugs, drug effects, drugs and driving, pregnancy, treatment, statistics, drugs and the law and where to go for help and further information.