A psychoactive drug is a chemical substance which, when consumed, can affect the brain and nervous system, resulting in an altered mental state. The potent effects of psychoactive drugs have led some to be used as prescription medicines, while others have become some of the most widely prohibited illicit substances in the world. So what are the effects of drugs on the brain? What are the different types of psychoactive drug, and how do these various chemicals affect behaviour, consciousness, mood, perception, and the functioning of the brain?
Depressants slow brain and nervous system functionShow moreShow less
Depressant drugs inhibit signals in the brain and nervous system, reducing neuronal messages and slowing the brain's activity down.
The active compound in alcoholic drinks, ethanol, works on two of the brain's most important neurotransmitters, the molecules which transmit signals between networks of neurons. Ethanol increases the effects of gamma aminobutyric acid, the primary neurotransmitter which inhibits neuronal signalling, and suppresses the effects of glutamate, the major excitatory neurotransmitter.
The combined impact of these interactions on the brain is to slow neural function, lowering reaction times, worsening cognitive abilities, and enhancing sociability by lowering anxiety and social inhibitions. Consumption of large quantities of alcohol can eventually depress brain activity to the point of unconsciousness or even death, and over a longer period of time, alcohol consumption is associated with a decrease in brain volume.
[P1] Alcohol interacts with the brain to slow neural function.