"Memory Eraser" Clue to Alzheimer's

Depression and obesity link, cell phone and brain tumor controversy, schizophrenic particle

BIG AND LONELY WOMEN

LILLE, France

Overweight women are more likely than others to be depressed, while glum males tend to be slim, according to a ten-year French statistical study that also found a correlation between people's weight and the amount of reading they do.

    Dr. Jean-Michel Borys found a quarter of overweight women in a sample of over 6,000 people suffering from depression, against only 14 percent of women without weight problems. There was no clear correlation, however, between depression and obesity in men-possibly because many depressed men are also heavy smokers, which stops them putting on weight, the study said.

    Short of chain-smoking, women may however manage to stave off obesity by reading, it suggested. The research found that women who read a lot were far less likely to be overweight, and suggested that reading inspired them to seek a healthy balance in their lives and to exercise more. Conversely, women with obesity were often poorly educated.

    The study also found a link between obesity and the gene responsible for producing insulin in the body, which may explain why some families seem more vulnerable to obesity than others. The gene sets the amount of glucose that the body stocks in muscle and fatty tissue-more in some people than others.

    A total of 6,666 people from the northern French towns of Fleurbaix and Laventie took part in the study. Northern France was chosen for the study because it has the highest rate of obesity and cardiovascular disease in the country.

SOYA FIGHTS CANCER

LONDON

New research suggests that soya milk and tofu-soya bean curd-may reduce the risk of breast cancer.

    Diets rich in soya appear to affect the make-up of breast tissue, said scientists from the charity Cancer Research UK, which carried out the research with the National University of Singapore and the US National Cancer Institute. Women who ate a lot of soya were much less likely to have the "dense" tissue associated with breast cancer, the researchers said.

    Scientists had previously suspected that eating soya might contribute to the low breast cancer rates in countries like China and Japan. But until now, the evidence has proved inconclusive.

    The new study of 406 women living in Singapore found that women who ate the most soya were 60 percent less likely to have "high risk" breast tissue than those who ate the least.

    Said Cancer Research UK's Stephen Duffy: "This research shows for the first time how the amount of soya a woman eats may have an effect on breast tissue and in turn may potentially reduce her risk of breast cancer."

    Scientists think the active ingredient in soya is isoflavone, a member of a family of plant chemicals called phytoestrogens that mimic that action of the female sex hormone estrogen.

    Many cases of breast cancer are largely caused by the way estrogen acts on breast tissue. Isoflavone may block estrogen in the breast. Exposure to phytoestrogens seem to lengthen a woman's menstrual cycle. Previous research has suggested that the fewer menstrual cycles a woman goes through in her lifetime, the lower is her risk of breast cancer.

    Breast cancer affects more than 40,000 women in UK. Paul Nurse, interim chief executive of Cancer Research UK, said "the findings make an important contribution towards our ongoing studies on the relationship between diet and cancer, and may eventually point to new ways of preventing breast cancer."

MOLECULE TO FORGET

PARIS

A molecule that helps the brain delete unwanted information could be to blame for the memory loss which creeps up with old age, according to a Swiss study.

    "Not everything that we learn is useful, so the brain needs a mechanism to prevent itself from being burdened by unhelpful details," said researchers Alcino Silva and Sheena Josselyn in an article in Nature.

    Studies on mice by the Swiss Federal Institute of Technology in Zurich found that those in which the activity of a protein called protein phosphatase-1 (PP1) was inhibited were less likely to forget what they had learned, said the institute's David Genoux. The enzyme "actively suppresses memories in mice, both during and after a learning exercise," the article said.

    The study was "unraveling the basis of forgetfulness" and had found these "molecules of forgetfulness" which were part of a complex system that clears the brain of unwanted memory and allows relearning. The results show "we are well on our way to unraveling the biology of memory, and of course, forgetting," said Silva and Josselyn of the University of California.

THEY DO?

STOCKHOLM

Owners of older mobile telephones are at substantially greater risk of contracting a brain tumor, a Swedish study reveals.

    Researchers spent four years studying 1,617 patients with brain tumors in central Sweden-in what they said was the largest study so far on first-generation mobile phones and cancer risk-and compared them with a healthy control group. The result showed that users of Nordic Mobil Telephone (NMT) phones were from 1.3 to 3.5 times greater at risk of developing cancer than those who did not use those phones.

    "It is clear that NMT users should exercise caution," Kjell Hansson Mild of the Swedish National Instititue for Working Life, coauthor of the study with Lennart Hardell of Orebro University Hospital, said. Hansson Mild carried out his study on users of first-generation NMT mobile phones, looking at the short-term risk of cancer, and over a 10-year period.

    NMT users were shown to run a 1.3 times greater risk, and over a 10-year period the overall tumor risk was 1.8 times greater, the study showed. The risk of a tumor developing in the temporal lobe of the brain-on the side of the head where the phone is used-was 2.5 times higher. Still higher were the chances of tumors (3.5 times) in the auditory nerve.

    Hansson Mild said that the risk of cancer was not as clearly established for users of GSM phones, the most-widely used type of mobile phone today. But he also pointed out that GSM phones had not yet been in circulation for many years, and no one in the study had been using such a phone for more than a decade.

    "Although we can see similar tendencies (with GSM phones), any conclusions regarding these phones must wait until the results of other ongoing studies are published," he said.

THEY DON'T?

SYDNEY

Australian scientists said new research had found no link between the use of digital mobile telephones and cancer. The team at Adelaide's Institute of Medical and Veterinary Science said its latest findings contradicted an earlier study, which concluded that longtime use of cellular telephones could cause cancer.

    In the latest project published in Radiation Research, researchers exposed 1,600 genetically modified and "wild type" mice to differing levels of mobile phone radiation for an hour a day over two years. The scientists found no increase in the mice's lymphoma rate, even though the transgenic mice had been bred with a "hair-trigger" tendency to develop tumors in response to cancer-promoting changes in their environment.

    The findings contradicted an earlier Adelaide study in which the same type of mice developed double the number of cancers when exposed to 900 megahertz mobile phone radiation. That study prompted widespread concern because it was the first reputable research pointing to a strong link between mobile phones and cancer. The new research repeated the earlier work but with more mice and stricter control over how they were exposed to the radiofrequency energy.

    Tim Kuchell, leader of the latest project, said other aspects of mobile phone radiation still had to be explored and were the subject of work now underway in Italy and elsewhere. "We're left with some of the other questions about headaches, sleep disorders, etc.," Kuchell said. "Which can only really be answered satisfactorily with human studies and they are ongoing both in Australia and overseas," he added.

EXPLAINING SCHIZOPHRENIA

STOCKHOLM

Swedish researchers said they had discovered an unidentified particle present in the cerebrospinal fluid of schizophrenics that could help explain the causes of the disease.

    "We have found a marker for the disease. The next step is to find out if this is a general phenomenon worldwide, or just in Scandinavian patients," said Lennart Wetterberg of the Karolinska Institute research team. Wetterberg said the particle did not appear to be virus or bacteria, but could be either part of a disturbed brain membrane or a new life form. "This could be a new life form. This is of course a hypothesis that we are testing," he said.

    In the study, the particle was found in 20 of 22 Scandinavian schizophrenic patients. Only two of 38 people who did not suffer from schizophrenia were found to have the particle. "Now we have to find out if this particle appears in the beginning of the disease or if it is part of the healing process. We don't know at what stage the particle first appears," he said.