 |
 |
IN THE LAB - Alzheimer's May Respond To New Drug By Linda Marsa, Special to The Times October 27, 2003 People with Alzheimer's disease received some encouraging news this month when the U.S. government approved the first drug for those in the late stages of the disease. That medication, Namenda, or memantine, may be just the beginning. A new type of drug called ampakines promises not just to treat Alzheimer's but also to prevent memory loss in healthy people and combat other neurological ills that afflict millions. "These are going to be the first broad-spectrum psychiatric medicines," says Gary Lynch, a UC Irvine neuroscientist who first devised ampakine drugs. "Essentially, many of your psychiatric diseases do turn out to be a confusion in cortical communication." Scientists believe that the gradual weakening or failure of the brain's electrical circuits may be at least partly responsible for Alzheimer's and age-related memory deterioration; a misfiring of these neural connections may trigger such diverse ailments as autism, Parkinson's disease and schizophrenia. Ampakines seem to enhance communication among brain cells, "like turning up the dimmer on a light switch," says Gary Rogers, a chemist with Irvine's Cortex Pharmaceuticals, which has pioneered the development of ampakines. Early tests suggest that the synthetic compounds may not only sharpen memory but also stave off symptoms of Alzheimer's and Parkinson's disease, improve mental acuity in those suffering from a genetic form of mental retardation, help people with schizophrenia think more clearly and even make the sleep-deprived more alert. "Ampakines are a reasonable scientific avenue to pursue," says Dr. Robert Malenka, a neuroscientist at the Stanford University School of Medicine in Palo Alto. "But while they're exciting," he cautions, "we're still in the early days, and we probably won't know for several years whether they work." The ampakine drug that is furthest along is Cortex's CX-516, which is being tested as a treatment for schizophrenia, Alzheimer's disease, autism and fragile X syndrome, the leading cause of inherited mental retardation. However, studies of CX-516 as a memory enhancer have generated the most attention because of the huge anticipated need and enormous potential market. In 10 years, all 77 million baby boomers will be older than 50, and one in four may eventually develop some form of dementia. Preliminary research has been encouraging. The drugs appear to work by enhancing glutamate, a chemical messenger that expedites the transmission of at least 75% of the electrical signals between brain cells. In a 1997 Swedish study, a dozen medical students who were given the drug showed significant improvement on four cognitive performance measures. In another 1997 study, 24 volunteers ages 65 to 75 and 36 volunteers in their 20s were given a memory test. After some of these seniors were given the drug, their test scores tripled; these results were similar to those in the younger group. "The drug brought them about two-thirds of the way back to the 25-year-olds," Lynch says. A more extensive study has just been completed on 175 people ages 55 to 75 who suffer from frequent memory lapses, a condition called mild cognitive impairment that afflicts an estimated 8 million Americans older than 50. Although people with the condition can still function, many progress to Alzheimer's. Half of the volunteers took CX-516 three times a day for 28 days, and the rest were given a placebo, or dummy pill. Results should be available in early 2004. Experts say that drugs like CX-516 are only the beginning, however. "In the past two years, the field has gone crazy," Lynch says. * Other drugs in development More than 60 drug companies around the world are devising other types of memory-enhancing drugs. At least a dozen are in the early stages of human tests, and they all work in different ways. SGS742, for example, which is being developed by Saegis Pharmaceuticals of Half Moon Bay, Calif., blocks GABA, a brain chemical that can inhibit memory consolidation. Another drug, MEM 1414, which is made by Memory Pharmaceuticals in Montvale, N.J., prevents the breakdown of cyclic- AMP, a brain chemical that plays a key role in the formation of long-term memory. Still another, Axonyx's Phenserine, which is being tested in Alzheimer's patients, inhibits the action of an enzyme that destroys brain chemicals essential for memory and cognition. "If any of these drugs work, they're potentially worth billions," says Dr. Robert Malenka, a neuroscientist at the Stanford University School of Medicine. SOURCE: Los Angeles Times, CA http://tinyurl.com/ssvj * * * ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn