www.SciAmMind.com SCIENTIFIC AMERICAN MIND 7

Once an alcoholic, always an alcohol-ic—the saying is decades old, but sci-entists have only recently uncovered why it is often true. Long-term alcohol abuse changes the brain, making a person more sensitive to stress and more likely to reach for the bottle to soothe his or her anxiety. According to a new study, drugs that inhibit these stress pathways could help recovering alcoholics stay in control.

Scientists at the National Institutes of Health and University College Lon-don bred mice lacking the neuro kinin 1 receptor (NK1R), a protein involved in the brain’s stress response. The mice were given unlimited access to alcohol-spiked water for 60 days, during which the alcohol content was incrementally raised from 3 to 15 percent. The NK1R-defi cient mice consumed far

less alcohol—especially later in the trial when alcohol concentration was higher—than the normal mice did. They were also more sensitive to alcohol’s effects than the normal mice were; studies have shown that the more sensitive a person is to alcohol, the less likely he or she is to abuse it.

The team then treated 25 highly anxious recovering alcoholics with a drug that blocks the NK1 receptor. After four weeks of hospital treatment, the subjects taking the drug reported fewer spontaneous and stress-induced alcohol cravings than patients given a placebo did. When the scientists used functional MRI to look at the subjects’ brain activity, they found that the treated subjects showed less activity in the insula, a region associated with craving. The scientists believe the drug

targets a stress pathway specifi c to alcoholics because it has been shown to have little effect on stress levels in other types of patients.

Lead author Markus Heilig of the NIH cautions that although the study is promising, it does not prove that the drug will help alcoholics long-term. Scientists “need to do studies in outpatients and look at reduction in drinking,” he says. A larger clinical trial designed to do just that will begin recruiting subjects later this year. —Melinda Wenner

ADDICTION

Ease Anxiety, Curb CravingsBlocking a stress mechanism in the brain diminishes alcohol urges

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The deadliest and most com-mon type of brain cancer has a strange bedfellow: cytomega-lovirus, a kind of herpes pres-ent in about 80 percent of the U.S. population. Now scien-tists are exploiting this coinci-dence to treat the cancer with a vaccine that targets the virus and slows tumor regrowth.

In 2002 scientists showed that cytomegalovirus, or CMV, was active in the brain tumors but not the surrounding healthy tissue of all 27 patients they tested who had glioblas toma multi forme. CMV is dormant and undetect able in most people.

Neuroscientist Duane Mitchell of Duke University Medical Center and his colleagues confi rmed in 2007 that CMV is active in at least 90 percent of glioblastoma tumors. Now Mitchell’s team has developed an experimental vaccine that triggers the immune system to attack CMV, thereby attacking its tumor tissue home. As reported at the American Society of Clinical Oncology meeting earlier this year, the vaccine, together with radiation and chemo -therapy, prevented the brain tumor from

reemerging after surgery for 12 months as compared with the typical six to seven months with no vaccine. Patients’ average life span increased from 14 months to more than 20.

So does this herpesvirus cause cancer? The answer is unclear: tumor cells may simply be a fertile ground for growing the virus, as cells such as these often lack the normal immune functions that suppress CMV reproduction. But University of Wisconsin–Madison researchers reported in May that the virus has the ability to take over a cell’s braking mechanism and cause uncontrolled reproduction. Even so, the numbers do not seem to add up: four of fi ve Americans has CMV, but only about one in 30,000 ends up with glioblastoma. And a small number of glioblastoma patients do not have CMV in their tumors.

“Most evidence to date does not support CMV being a cancer-causing virus,” Mitchell says. Don Diamond, a virologist at the City of Hope Cancer Center near Los Angeles, agrees: his extensive research on CMV and cancer has convinced him the virus does not cause tumors. But for patients it does not matter whether the connection between herpes and brain cancer is causal or not—the vaccine appears to work. Mitchell hopes to have the vaccine ready for market in a few years. —Victoria Stern

MEDICINE

Does Herpes Cause Brain Cancer?Targeting a common virus staves off tumor regrowth

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Cytomegalovirus