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Biotech / Medical : VD's Model Portfolio & Discussion Thread -- Ignore unavailable to you. Want to Upgrade?

To: Harold Engstrom who wrote (7989)	6/2/2000 9:35:00 AM
From: scott_jiminez	Read Replies (1) \| Respond to of 9719

Harold - yes I read that press release in putting together my post #7978. My view of the DAT hypothesis of ADHD is highly skeptical until supporting evidence grows MUCH more substantial. A news release from a company with a huge financial stake in expanding such evidence does not register whatsoever. There is evidence that methylphenidate (Ritalin) does indeed interact with the DAT, competing with dopamine (DA) for binding. The net effect is to raise the effective dopamine concentration in synapses thereby, in theory, counteracting the elevated DAT levels found in ADHD (DAT is a presynaptic uptake mechanism, regulating the amount of DA in the synaptic cleft at any given time). These data do lend support to the involvement of the DAT in ADHD. But to repeat the correlation vs. causation issue, 'lending support' does not imply by any stretch that DAT/DA abnormalities are diagnostic nor necessary for ADHD to become manifest. Two random samples to substantiate my point (as a reminder of some neurotransmitters (NTs) in the central nervous system, 1. the 'catecholamines' are dopamine, epinephrine [= adrenaline], and norepinephrine [= noradrenaline], 2. serotonin.): i. This study suggests that adrenergic NTs show higher correlation with ADHD than DA. ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10782925&dopt=Abstract These results indicate that the adrenergic genes play a greater role in ADHD than either the dopaminergic or serotonergic genes combined. ii. This study suggests that blood serotonin levels show higher correlation with (severe) ADHD than any other factor tested. ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10223434&dopt=Abstract We conclude that children with severe ADHD may have a different serotonin turnover compared to children with mild ADHD. Perhaps the serotonin data will only apply to severe cases. Perhaps not. ADHD is NOT a disease easily classified on a biochemical (or anatomical) basis. The disease CLEARLY involves a multitude of CNS systems and will require a substantial amount of collaborative work to piece together the whole picture. Unfortunately, much of neuroscience suffers from the blind man/elephant syndrome, each lab studying a single neurotransmitter system, finding a deficit in that NT associated with a pathology, and proclaiming 'victory'. As night follows day, another lab will subsequently express similar joy...based on a completely distinct NT system. There is evidence that methylphenidate ingestion is associated with vasculitis (i.e. stroke) ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10805196&dopt=Abstract We draw your attention to the risk of using methylphenidate for a long period of time.The ADHD/Ritalin problem is real and must be addressed. However, there is just as much danger in proposing diagnostic procedures based on tunnel-visioned hypotheses as there is in leaving the current state of patient evaluation unchanged.