Here is more evidence for the theory that Alzheimer's is due to a special form of insulin-insensitive diabetes of the brain. Insulin blocks toxic proteins from damaging nerve cells.
EVANSTON, Ill. --- A Northwestern University-led research team reports that insulin, by shielding memory-forming synapses from harm, may slow or prevent the damage and memory loss caused by toxic proteins in Alzheimer's disease.
The findings, which provide additional new evidence that Alzheimer's could be due to a novel third form of diabetes, will be published online the week of Feb. 2 by the Proceedings of the National Academy of Sciences (PNAS).
In a study of neurons taken from the hippocampus, one of the brain's crucial memory centers, the scientists treated cells with insulin and the insulin-sensitizing drug rosiglitazone, which has been used to treat type 2 diabetes. (Isolated hippocampal cells are used by scientists to study memory chemistry; the cells are susceptible to damage caused by ADDLs, toxic proteins that build up in persons with Alzheimer's disease.)
The researchers discovered that damage to neurons exposed to ADDLs was blocked by insulin, which kept ADDLs from attaching to the cells. They also found that protection by low levels of insulin was enhanced by rosiglitazone.
Diabetics have a significantly greater risk of dementia, both Alzheimer's disease — the most common form of dementia — and other dementia, reveals important new data from an ongoing study of twins. The risk of dementia is especially strong if the onset of diabetes occurs in middle age, according to the study.
"Our results . . . highlighted the need to maintain a healthy lifestyle during adulthood in order to reduce the risk of dementia late in life," explained Dr. Margaret Gatz, who directs the Study of Dementia in Swedish Twins.
In a study published in the January 2009 issue of Diabetes, Gatz and researchers from Sweden show that getting diabetes before the age of 65 corresponds to a 125 percent increased risk for Alzheimer's disease. Nearly 21 million people in the United States have diabetes, according to the American Diabetes Association, which publishes the journal.
Eating less to remember more might become a new prescription for some elderly people, German researchers say.
They found that memory and thinking skills improved among healthy, overweight subjects who cut their calorie intake by 30 percent over a three-month period.
If further research supports this conclusion, "from a public health point of view, you could actually do something for the prevention of cognitive decline from aging," said lead researcher Dr. Agnes Floel, assistant professor of neurology at the University of Munster.
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