Study suggests insulin may be treatment for Alzeheimer's

Insulin appears to shield the brain from toxic proteins associated with Alzheimer's disease, U.S. researchers said on Monday, supporting a theory that Alzheimer's may be a third form of diabetes.

Nerve cells from the hippocampus a part of the brain that is critical to memory, were treated with insulin and the drug Avandia in a study conducted at the Northwestern University. Avandia is a drug used to treat type 2 diabetes. Researchers discovered that insulin protected the cells from proteins called amyloid beta-derived diffusible ligands (ADDLs), which attack nerve connections in the brain.

The study said that GlaxoSmithKline's diabetes drug Avandia, or rosiglitazone appears to enhance the protective effect.

Researchers say that the discovery that insulin may slow or prevent Alzheimer's-related memory loss support theories that propose that the disease may be a third type of diabetes.

In Alzheimer's large sticky plaques of a substance called amyloid beta protein are appear in the brain tissue. These plaques cause memory loss, confusion and the inability to care for oneself with the condition finally progressing to death.

Persons who have type 2 diabetes lack the capacity to produce enough insulin, or the body is unable to use insulin properly. The latest research suggests that there may be a ''type 3'' diabetes. According to available evidence brain cells need insulin to survive and a drop in insulin levels leads to brain cell damage. If the damaged cells are located in the hippocampus it may lead to memory loss.

"Recognizing that Alzheimer's disease is a type of brain diabetes points the way to novel discoveries that may finally result in disease-modifying treatments for this devastating disease," says Sergio T. Ferreira, a member of the research team and a professor of biochemistry in Rio de Janeiro, Brazil.

In the current study, researchers found that insulin prevent ADDLs from attaching to connections between nerve cells, protecting them from damage. They also discovered that Avandia boosts the capacity of insulin at lower levels to shield against the harmful effects of ADDLs. They say that the discovery opens up new ways and new hope for fighting the debilitating disease.

"Therapeutics designed to increase insulin sensitivity in the brain could provide new avenues for treating Alzheimer's disease," says William L. Klein, a professor of neurobiology and physiology in the Weinberg College of Arts and Sciences and a researcher in Northwestern's Cognitive Neurology and Alzheimer's Disease Center. "Sensitivity to insulin can decline with aging, which presents a novel risk factor for Alzheimer's disease. Our results demonstrate that bolstering insulin signaling can protect neurons from harm."