Posted by Quintal on February 4, 2007, at 9:29:45
In reply to I was wrong about the needle in a haystack, posted by Squiggles on February 4, 2007, at 9:00:39
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CLARIFICATION ABOUT BRAIN DAMAGE
by Professor Heather Ashton
August 29, 2002I agree that there is an abundance of people with very long-term problems and I have never denied that benzos can cause lasting, possibly permanent, neurological and other symptoms (see my articles on protracted withdrawal syndromes). What I have said is that there is no convincing evidence to date that they cause structural brain damage - e.g. death of neurons, brain atrophy etc. I think that long-lasting changes are probably functional, at the level of the GABA/BZ receptors which fail to revert to their pre-benzodiazepine state, often leaving the nervous system hyperexcitable (paraesthesiae, formication, muscle twitches, fasciculation, sensory hypersensitivity, tinnitus, jaw and dental pain, insomnia etc.) or generally unregulated/uncoordinated (cognitive) problems. Being functional changes, they are potentially capable of resolving which is why many people do notice gradual, if incomplete, improvement over the years.
Professor Lader himself carried out CAT scan studies on long-term benzodiazepine users and failed to find definite structural brain changes. As you know I tried several times unsuccessfully to obtain a grant for MRI studies in long-term benzo users who have withdrawn (combined with neurocognitive and EEG measurements), and to my knowledge no such study has ever been performed. Several correspondents have had MRI scans which have been reported as normal. On the other hand, I have of course seen many patients with long-lasting tinnitus, paraesthesiae, muscle spasms and joint pains etc. which are reported in my papers on protracted withdrawal. See especially the 1991 paper.
However, neither CAT scans nor MRI can reveal functional as opposed to structural changes. A search for structural changes would require very careful comparisons of brain volumes, hippocampal size, ventricular volume etc, in benzo users compared to age, sex and IQ matched controls; or else prospective longitudinal studies, again comprising benzo users with matched non-users over the long term. Cerebral blood flow measurements (fMRI) or PET (positron emission tomography) of GABA receptors might be more informative about functional changes, but have not been carried out.
http://www.benzo.org.uk/ashanswer.htm
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poster:Quintal
thread:729581
URL: http://www.dr-bob.org/babble/20070201/msgs/729583.html