Posted by Dave001 on August 29, 2005, at 2:30:32
In reply to Re: Neurotoxicity is a pretty sketchy term, posted by linkadge on August 28, 2005, at 16:50:15
> Why even wait for more conclusive evidence? Why bother to pick at the
> wording of the study? I think it is fully concievable that
> stimulants can induce dammage to the dopaminergic neurons.
>
>
> Sure they do die on their own, why accelerate that rate?I agree. At the very least, one should be aware of the potential for
damage, whether or not it _does_ occur at therapeutic doses. That
amphetamines can cause lasting damage to dopaminergic neurons in animals
has been known for a long time, but what has been inexplicably dismissed
is the need to determine the level at which humans are susceptible to
such damage, and to find a maximum dose range that provides a reasonable
margin of safety.There are obvious difficulties with conducting studies of neurotoxicity
in humans, but at least non-human primates make it much easier to
extrapolate doses. It's plausible that say, 10 mg/day in rats is
comparable with doses used in humans in clinical practice. Adjusting for
body surface area alone would account for much of the difference, and
then one must consider the much faster rate at which amphetamines are
metabolized in rats (independent from body mass/surface area variables).
Researchers have tried to account for latter variable using methods of
administration that provide a continuous release of drug via infusion or
(IIRC) implantable pellets.[...]
> called one's life-force. Eighty percent loss of dopamine neurons
> results in Parkinson's disease, often prefigured by depression."That's another problem: the symptoms of neuronal degeneration would
probably only manifest after a large amount of damage had already
resulted. The brain seems to adapt pretty well until neurons drop below
a critical level, not to mention amphetamine itself could mask some of
the deterioration. Tolerance is underappreciated.Dave
> Linkadge
poster:Dave001
thread:547372
URL: http://www.dr-bob.org/babble/20050827/msgs/547977.html