Here's some studies so far. The first link of more of a discussion around addiction. I don't think I could just put links up, discussing PAWS / protracted withdrawal without putting up a link discussing addiction. Hope these are helpful. Please let me know what you think or include any that may help. I can collate them and have them in the first page so they can help anyone going through this to research what is happening to them.
Moal, M.L., & Koob, G.F., (2007). Drug Addiction: Pathways to the Disease and Pathophysiological Perspectives
http://www.sciencedirect.com.voyager.chester.ac.uk/science/article/pii/S0924977X06002318
Satel, S.L., (MD), Kosten, S.R., (MD), Schuckit, M.A., (MD), & Fishman, M.W., (PhD) Should Protracted Withdrawal From Drugs Be Included in DSM-IV?
http://search.proquest.com.voyager.chester.ac.uk/docview/220477339
Aston-Jones, G., (2004). Brain substrates for increased drug seeking during protracted withdrawal
http://www.sciencedirect.com.voyager.chester.ac.uk/science/article/pii/S0028390804001819
Ashton, H. (1995) Protracted Withdrawal From Benzodiazepines: The Post-Withdrawal Syndrome
http://search.proquest.com.voyager.chester.ac.uk/docview/894195436
MORE LINKS...
More links...
Smith, R.J., & Aston-Jones, G. (2008). Noradrenergic transmission in the extended amygdala: role in increased drug-seeking and relapse during protracted drug abstinence
http://search.proquest.com.voyager.chester.ac.uk/docview/212035018
Gowing, L.R., (Dr.), Ali, R.L., White, J.M., 'The Management of Opiod Addiction'
DOI: 10.1080/713659366 (website link is too long so please look via title or DOI)
Shi, J., Zhao, L., Epstein, D.H., Zhang, X-L., Lu, L. (2007).Long-term methadone maintenance reduces protracted symptoms of heroin abstinence and cue-induced craving in Chinese heroin abusers
http://www.sciencedirect.com.voyager.chester.ac.uk/science/article/pii/S0091305707001323
Barr, J.L., Renner, K.J., Forster, G.L. (2010). Withdrawal from chronic amphetamine produces persistent anxiety-like behavior but temporally-limited
reductions in monoamines and neurogenesis in the adult rat dentate gyrus
http://www.sciencedirect.com.voyager.chester.ac.uk/science/article/pii/S002839
Evey xxxx