My understanding is that it will affect the way your brain works in terms of the chemistry but that will come back over time. I know it killed my ability to feel emotions properly and thats slowing coming back for me. I dont know how long is too long but if you are off now, good for you. Please stay off..its a nightmare worse than any physical pain.
Our brains are very adaptive & there are things that you can do to increase the likelihood of being one of the 90% who achieve full recovery.
Most importantly, regularly exercise your body & your brain. Get your heart rate pumping & learn a new skill or do puzzles.
The amino acid d-phenylalanine can help restore natural endorphins in some people. Sex is also helpful.
"The brain that changes itself" by neuroscientist, Dr. Norman Doidge, is a great resource for the best ways to improve the health of your brain. For inspiration, read Jill Bolte Taylor's "My stroke of insight", about her complete recovery from a stroke that left her paralysed and speechless.
I have been off of Roxycodone, Oxycodone, the Fentanyl patch (100 mcg), Advair, Albuterol, the water pill (I was 210 lbs.), Effexor, Xanax, Hydrocodone, cortisone shots in my lower back, Abilify (why, I don't know), since June 2, 2009. I was sick 24/7 for 8 months with nausea, lost 85 lbs easy because I was too sick to eat but had to force feed myself just to stay alive. I am 62, in excellent health, nothing wrong with my organs, no growths, no health problems, but a lower back of 4 herniated disks which I went to spinal decompession for 58 sessions. I am now out of pain and my lower back is not completely healed, but I am out of horrific pain. I have to go periodicly to my chiropractor to straighten my spinal health and go to spinal decompression with the DRX 9000 machines. The only thing I feel is that I do not feel happy, or right in my own skin. I take a comprehensive amino acid therapy program geared to keep myself calm and to balance the brain's neurotransmitters. My memory is perfect. I took a test last April and found that I had extremely low levels of calming aminos and high levels of excitatory aminos in my body. So a program was set up for me by Neuroscience Labs to correct the inbalances. However, I still do not feel right 80% of the time. I do not know if it just takes time or that I want to find out if there is something else I can do or take like meditation practice again. I was a meditator for 30 years. It was wonderful, but then I had an accident which injured my lower back and herniated 4 disks. Looking into other aminos or products for recovery.