Scientists target brain enzyme as they inch closer to Alzheimer's origins

A laboratory study seems to support the theory that a buildup of beta-amyloid plaques in the brain is the first step in a process that leads to Alzheimer's disease.

Researchers pinpointed the important role of a particular enzyme in this process, and they believe the enzyme could offer a target for new drugs to fight Alzheimer's.

The theory that accumulation of beta-amyloid plaques triggered Alzheimer's disease was first suggested in the mid-1980s.

"One of the biggest questions since then has been whether beta-amyloid actually triggers the formation of the [fiberlike] tangles that kill neurons," said study co-senior author Rudolph Tanzi, director of the Genetics and Aging Research Unit at Massachusetts General Hospital.

According to the researchers, scientists had been stymied by laboratory cell cultures that can't replicate the "gelatinous" 3-D environment of the brain. They say their new approach gets closer to replicating that environment.

After growing special neural stem cells in the laboratory for six weeks, Tanzi's team noticed that cells tied to a fast-progressing form of Alzheimer's disease not only boosted levels of beta-amyloid, but also contained the "neurofibrillary tangles" that are the other hallmark of the disease.

"In this new system that we call 'Alzheimer's-in-a-dish,' we've been able to show for the first time that amyloid deposition is sufficient to lead to tangles and subsequent cell death," Tanzi said.

The researchers also found that boosting levels of a particular enzyme appeared to help reduce formation of the toxic tangles.

The findings were published online Sunday in the journal Nature.

Tanzi said that the new lab system could "revolutionize" drug discovery. -- HealthDay