Does paroxetine causes permanent slow cognition, loss of alertness and attention?

Forever's very long: Withdrawal is a serious issue w/ this and many other psych drugs. It's serious and needs to be tapered and you need to be monitored. But, when you are off it - side effects should go away. Especially if you taper correctly, you'll be your old self. Of course, if that was a bit poor in those - you'll still be. Consider CBT therapy or Meditation to enhance those functions. It's quite possible. Best!

Not permanent: The side effects of Paxil, (paroxetine) as with many SSRI antidepressants can cause slower cognition, and loss of alertness and attention, however, these side effects should go away, or dissipate when the drug is stopped, with a few weeks. Since depression can also cause these symptoms, I would be careful blaming this on the drug if it hasn't been taken for at least 4-6 weeks regularly