Good posts. A few comments:
QUOTE(Firephoenix @ Jun 2 2009, 07:40 PM)
"Absinthe - besides exceedingly high amounts of ethanol, absinthe also contains thujone, a GABA receptor antagonist. Effectively, thujone is the opposite of benzodiazepine anticonvulsant/tranquilizers (such as Xanax and Valium). Unsurprisingly, in high doses, thujone has been proven to cause seizure and death. Fortunately (or unfortunately, if you're looking to damage your brain cells), the European Union places restrictions on thujone content in absinthe, ensuring the drink's psychoactive and neurotoxic qualities arise from the high alcohol content, and not the thujone.
It doesn't seem like any absinthe ever contained much thujone, as an interesting aside. It got hyped up for a while as a supposed reason absinthe was worse than other alcohol, but like most anti-drug campaigns it turned out to be bullshit.
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Alcohol - while the greatest ethanol-induced brain damage results from vitamin deficiencies (see Wernicke-Korsakoff Syndrome below), alcohol itself can also result in structural changes within the brain. Since ethanol has a variety of pharmacological effects, it's difficult to tell exactly how the damage arises, but MRI evidence shows decreased brain volume in alcoholic patients.
Yeah, no argument there.
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Dissociatives (DXM, MK-801, PCP, Ketamine) - A study by J.W. Olney showed that in rat models, administration of normal doses NMDA receptor antagonist drugs resulted in over-excitation and death of neurons as a result of malfunction of intracellular organelles (specifically, the mitochondria and endoplasmic reticulum). Since then, additional studies have shown many kinds of cognitive deficits in chronic ketamine users.
Also no argument, but with a caveat: There's a bit of controversy as to the brain-damaging effects of dissociatives. Last I read it was becoming more uncertain as to whether or not Olney's Lesions were caused by DXM at all, or perhaps only excessive use (for example), but I haven't researched this a lot so anyone wanting to try ketamine or DXM should look it up. I wouldn't recommend PCP at all, ever. It's got a bad rap, but not entirely unfairly.
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MDMA (Ecstasy) - MDMA has been proven to produce damage to serotonin neurons in rats and mice due to oxidative stress and free radical damage. Some have claimed that fMRI evidence demonstrates similar damage in humans, although many have disputed these studies. There have also been several studies showing memory deficits in those who abuse MDMA. Administration of a SSRI such as fluoxetine (Prozac) within 4-6 hours of MDMA use may reduce the risk of damage. The media has hyped MDMA's relationship to dehydration, which can also produce brain damage (see below).
Methamphetamine (speed, meth, ice, way too many Vicks Vapor Inhalers, etc.) - like MDMA, methamphetamine appears to produce oxidative stress, but damages dopamine rather than serotonin neurons. As a result, chronic methamphetamine abusers often show early-onset symptoms of Parkinson's disease and other cognitive deficits. Recent research has shown that prior administration of a free radical scavenger such as N-acetylcysteine can attenuate damage. Like any other stimulant, methamphetamine can also produce stroke (see below).
MPTP - MPTP results from improper synthesis of MPPP, a synthetic opioid. A single dose can result in severe damage to dopamine neurons, producing symptoms resembling those of Parkinson's disease. MPTP is often used to produce animal models of the disease to test new treatments.
All true. It's worth noting, though, that most opioids (morphine, heroin, the like) aren't neurotoxic at all. In fact, I can't think of a single commonly used opioid that is. They are pretty benign drugs and my personal favorites. Addictive, overdose, and improperly identified or synthesized drugs (i.e. MPTP) are still dangers, of course.