In the case of PTSD sufferers, scientists are undertaking the effort with fascinating results:
Researchers study the mechanisms of fear by testing rats’ abilities to learn to associate ordinarily neutral stimuli, like beeping noises, to unpleasant stimuli, like electric shocks. When researchers condition rats to expect a shock upon hearing beeps, making the beep a “conditioned stimulus,” fear learning is said to have taken place. Likewise, when they learn to dissociate the conditioned stimuli with the shocks, called the “unconditioned stimuli,” this is evidence of fear extinction. …
Dr. Burghardt’s study showed that when rats were treated with an [antidepressant] SSRI called tianeptine, it drastically altered their capacities for fear extinction. Rats that received short-term SSRI treatments—they got the drug for 9 days—developed a greater capacity for fear extinction. Conversely, rats that were treated for 22 days saw their ability to cultivate fear extinction become impaired.
Researchers also noted in the group treated for 22 days a decrease in the amount of a particular receptor protein largely affected by serotonin activity. This suggests that the protein, called the NR2B subunit of the NMDA glutamate receptor, is crucial in mediating the fear responses. Which means that the millions of people taking antidepressants for PTSD may be quashing their ability to successfully instigate fear extinction—and fear learning.
The Dish 