How Do Rapidly Acting Antidepressants Differ from Traditional Ones?

Recent efforts to develop rapidly acting antidepressants have highlighted the effects of ketamine, which both works quickly and seems to help severely treatment-resistant depressed patients. Because depressed patients have a bias to attend to negative information, researchers receiving some industry support explored the neural basis of ketamine and venlafaxine effects in an animal study using a novel “affective bias” paradigm.

The paradigm used separate exposures to medication and stress to induce a negative bias in rodents. Ketamine immediately reversed this acquired affective bias, but venlafaxine did not. When given before training, venlafaxine (but not ketamine) prevented the development of affective bias. The researchers examined mechan…