Final answer:
Psychoactive drugs affect the central nervous system by acting on neurotransmitters at the synapses between neurons, either as agonists or antagonists to enhance or decrease neurotransmitter activity.
Step-by-step explanation:
Psychoactive drugs interfere with normal neural transmission within the central nervous system, specifically at the synapses between neurons. These drugs can act as either agonists or antagonists to different neurotransmitter systems, thereby enhancing or decreasing the activity of certain neurotransmitters. Agonists may increase the synthesis of neurotransmitters, reduce their reuptake, or mimic their action by binding to receptors. Antagonists, conversely, may block the normal activity of neurotransmitters at their receptors, impeding their effects.
For example, drugs prescribed for Parkinson's disease often act as dopamine agonists to mimic the effects of dopamine, addressing the low levels of dopamine associated with the condition. Moreover, these drugs have a wide range of applications, including medical, ritual, and recreational uses. However, misuse can lead to addiction and require rehabilitation, which might involve psychotherapy and the use of other psychoactive substances.