Kathryn S. Kalasinsky

For more than 50 years, methamphetamine has been a widely used stimulant drug taken to maintain wakefulness and performance and, in high doses, to cause intense euphoria. Animal studies show that methamphetamine can cause short-term and even persistent depletion of brain levels of the neurotransmitter dopamine. However, the clinical features of Parkinson's disease, a dopamine deficiency disorder of the brain, do not appear to be characteristic of human methamphetamine users. We compared dopamine levels in autopsied brain tissue of chronic methamphetamine users with those in patients with Parkinson's disease and in a control group. Mean dopamine levels in the methamphetamine users were reduced more in the caudate (-61%) than in the putamen (-50%), a pattern opposite to that of Parkinson's disease. Some methamphetamine users had severely decreased dopamine levels, within the parkinsonian range, in the caudate (up to 97% dopamine loss) but not in the putamen. As the putamen and caudate subserve aspects of motor and cognitive function, respectively, our data suggest that methamphetamine users are not parkinsonian because dopamine levels are not sufficiently decreased in the motor component of the striatum. However, the near-total reduction in the caudate could explain reports of cognitive disturbances, sometimes disabling, in some drug users, and suggests that treatment with dopamine substitution medication (e.g. levodopa) during drug rehabilitation might be helpful.

An optical detection method, Raman chemical imaging spectroscopy (RCIS), is reported, which combines Raman spectroscopy, fluorescence spectroscopy, and digital imaging. Using this method, trace levels of biothreat organisms are detected in the presence of complex environmental backgrounds without the use of amplification or enhancement techniques. RCIS is reliant upon the use of Raman signatures and automated recognition algorithms to perform species-level identification. The rationale and steps for constructing a pathogen Raman signature library are described, as well as the first reported Raman spectra from live, priority pathogens, including Bacillus anthracis, Yersinia pestis, Burkholderia mallei, Francisella tularensis, Brucella abortus, and ricin. Results from a government-managed blind trial evaluation of the signature library demonstrated excellent specificity under controlled laboratory conditions.

The authors found that striatal levels of serotonin and those of its metabolite 5-hydroxyindoleacetic acid were severely depleted by 50 to 80% in brain of a chronic user of methylenedioxymethamphetamine (MDMA) whereas concentrations of dopamine were within the normal control range. Our data suggest that MDMA exposure in the human can cause decreased tissue stores of serotonin and therefore some of the behavioral effects of this drug of abuse could be caused by massive release and depletion of brain serotonin.