Barbiturates are known to do what?

Barbiturates are a class of drugs that function primarily as central nervous system depressants. They work by enhancing the effects of the neurotransmitter GABA (gamma-aminobutyric acid) in the brain. This action reduces neural excitability, which leads to a calming effect, often helping to alleviate anxiety. However, due to their depressant properties, barbiturates can also impair cognitive functions, including memory and judgment. This characteristic makes them useful in certain therapeutic contexts, such as for anxiety relief or as sedatives, but it also raises concerns about potential misuse and the risk of overdose.

The other choices do not accurately reflect the pharmacological effects of barbiturates. For instance, they do not stimulate the central nervous system, enhance cognitive functions, or improve respiratory functions in a beneficial way. Instead, while they may provide some respiratory control at therapeutic levels, at high doses they can significantly depress respiratory function, leading to dangerous consequences.