Research Review
1. Ecstasy can harm the brains of first-time users
Researchers have discovered that even a small amount of MDMA (better known as ecstasy) can be harmful to the brain, according to a first study to look at the neurotoxic effects of low doses of this recreational drug in new ecstasy users. The findings were presented at the annual meeting of the Radiological Society of North America (RSNA).
What is MDMA?
MDMA (3, 4-methylenedioxymethamphetamine, also known as ecstasy) is a synthetic drug that causes both hallucinogenic and stimulant effects. The drug was developed in Germany in the early twentieth century as an appetite suppressant, but today's users consume the drug for its hallucinogenic effects, which they claim heighten their senses and makes them feel less inhibited.
Many young users consume MDMA for its stimulant properties and to enable them to dance for hours at all-night parties and nightclubs. http://www.usdoj.gov/ndic/pubs3/3494/index.htm#
This research found a decrease in blood circulation in some areas of the brain in young adults who had just started to use ecstasy. According to Maartje de Win, Academic Medical Centre, University of Amsterdam, Netherlands, the findings also indicated a relative decrease in verbal memory performance in ecstasy users compared to the non-users.
Ecstasy is an illegal drug that acts as a stimulant and psychedelic. A 2004 survey by the National Institute on Drug Abuse (NIDA) found that 450,000 people in the United States age 12 and over had used ecstasy in the past 30 days. In 2005, NIDA estimated that 5.4 percent of all American 12th graders had taken the drug at least once.
Ecstasy targets neurons in the brain that use the chemical serotonin to communicate. Serotonin plays an important role in regulating a number of mental processes including mood and memory. Past research had shown that long-term or heavy ecstasy use can damage these neurons and cause depression, anxiety, confusion, difficulty sleeping and decrease in memory. However, no previous studies had looked at the effects of low doses of the drug on first-time users.
In this research, Dr de Win and colleagues examined 188 volunteers with no history of ecstasy use but at high-risk for first-time ecstasy use in the near future. The examinations included neuro-imaging techniques to measure the integrity of cells and blood flow in different areas of the brain and various psychological tests. After 18 months, 59 first-time ecstasy users who had taken six tablets on average, and 56 non-users, were re-examined with the same techniques and tests.
The study found that low doses of ecstasy did not severely damage the serotonergic neurons or affect mood. However, there were indications of subtle changes in cell architecture and decreased blood flow in some brain regions, suggesting prolonged effects from the drug, including some cell damage. In addition, the results showed a decrease in verbal memory performance among low-dose ecstasy users compared to non-users.
Dr de Win says "We do not know if these effects are transient or permanent. Therefore, we cannot conclude that ecstasy, even in small doses, is safe for the brain, and people should be informed of this risk. This research is part of a Netherlands XTC Toxicity (NeXT) Study which also looks at high-dose ecstasy users and aims to provide information on long-term effects of ecstasy use in the general population.”
2. Controlling Confusion: Researchers make insight into memory and forgetting
Why do we forget? Do memories decay on their own or are they harmed by interference from similar memories? Using a technique called "transcranial magnetic stimulation" (TMS), brain researchers at the University of Wisconsin-Madison may have found an answer.
Although the notion of decay makes sense, Brad Postle, assistant professor of psychology at UW-Madison, says it may be inaccurate. He says that "psychologists have known for decades that the intuitive notion of decay is probably less of a factor in forgetting than is interference. Interference occurs when other remembered information disrupts and competes with or confuses the information that we want to remember.
Interference is always present, but most of us do not always notice it. "An obvious case is like yesterday, when a friend was telling me his cell phone number but actually gave me his home phone number. Another scenario is equally familiar: we get most details of the story right, but misidentify the source. Or we remember that the quotation comes from Shakespeare, but we name the wrong play.
"Interference is also often to blame in cases when we simply cannot remember something. If blocking interference is so important to a good memory, where - and how - does that blocking occur?"
In a study published in the Proceedings of the National Academy of Sciences in the week of 4 December 2006, Postle (together with Guilio Tononi of the UW-Madison School of Medicine and Public Health, and Eva Federoes, a researcher in the UW-Madison department of psychology) studied how part of the brain's prefrontal cortex can reduce the disruptive effects of interference. The prefrontal cortex is responsible for complex thought.
From brain scans, scientists already knew that the sub-region under study, called the inferior frontal gyrus, or IFG, is active when volunteers take memory tests while confronting interference. But was the IFG essential to controlling interference, or was it just contributing more brain power to complex memory tasks?
To answer that question, the researchers temporarily disrupted the IFG using TMS, a non-invasive technique that shows potential for treating depression and other disorders.
According to Tononi, a pioneer in refining the technique for brain research, “…TMS is a technique that allows the induction of a current in the brain using a magnetic field that passes through the scalp and the skull safely and painlessly. TMS can be used to briefly 'scramble' neural activity in the underlying brain area for a short time, typically a second or so. This scrambling is fully reversible, and after the pulsing, the targeted brain area becomes fully functional again.
“Neuroscientists have traditionally identified the roles of particular parts of the brain by studying people with brain injury. TMS allows them to do a similar study on healthy volunteers. The great advantage for researchers is that one can test whether a given brain area is causally involved in producing a given behaviour, but as soon as the current is turned off, the brain returns to normal."
In the current study, volunteers read a group of letters (F, B, P, X), and were asked a few seconds later whether a particular letter had appeared in the most recent group (for example, did you just see a Z?). In this type of test, having seen a Z in the string-before-last causes interference that makes the task more difficult. The subjects take longer to respond, and are more likely to incorrectly say ‘yes’.
Postle adds that “the research set-up was designed to be a simplified version of many everyday memory challenges. Without a good sorting mechanism, our brains would be utterly confused by the vast amount of observations, ideas and memories that we have stored away. We might, for example, dial the phone number of the friend we just called rather than the one we intended to call.
”In previous studies of interference, the IFG consistently lit up in brain scans, showing that it does something when the memory tries to deal with interference. But the IFG could simply be contributing some type of generic processing power to the task. However, the new study proved that the IFG is essential to blocking interference because accuracy plummeted when the IFG got a brief jolt of magnetic stimulation at the exact moment when the subject was confronting confusion.
”Eventually, locating the site of specific memory operations in the brain may help the millions of people with declining memories. Understanding how the brain controls interference may be a first step to helping people with memory problems."
In this connection, Tononi adds that “the precise system used to target the magnetic pulse has many other applications in neuroscience research and treatment. TMS can be used not only to disrupt brain activity, but also to change it. If applied repeatedly, TMS can strengthen certain circuits that have become pathologically weak.
”TMS is already being tested to treat severe depression, one of the most serious psychiatric illnesses. In studying this treatment, it is important to be able to target TMS exactly to the right area for each individual brain, just as we did in this study."
For further contact:
David Tenenbaum, Brad Postle, University of Wisconsin-Madison, http://www.wisc.edu
Reference:
http://www.medicalnewstoday.com/medicalnews.php?newsid=58164
Monika Bhatia
Project Manager and Editor, Quality4life
13 December 2006
