Psychoactive drugs that slow down mental and physical activity are called inhalants stimulants hallucinogens depressants

There are 3 main categories of the psychoactive drugs namely stimulants, hallucinogens and lastly the depressants.The answer is depressants. They slow down the physical and mental ability of a person. Among the most used depressants are the barbiturates, tranquilizers and opiates.