Final answer:
Drugs that increase the actions of norepinephrine and/or serotonin by keeping them in synapses longer are used to treat clinical depression.
Step-by-step explanation:
Drugs that increase the actions of norepinephrine and/or serotonin by keeping them in synapses longer are most likely used to treat clinical depression. There are several classes of antidepressant medications that work by different mechanisms. For example, selective serotonin reuptake inhibitors (SSRIs) block the reuptake of serotonin into the presynaptic neuron, resulting in an increase in serotonin in the synaptic cleft.