Research on Brain Abnormalities May Lead to Progress in Alzheimer Therapies

Two types of brain abnormalities associated with Alzheimer's disease indeed appear to be linked, according to reports in Science magazine, raising hopes the discovery will "facilitate efforts to develop more effective Alzheimer's disease therapies."

Neurological deposits called plaques, made of beta-amyloid proteins, and tau tangles are both hallmarks of Alzheimer's disease, but until recently, the mice used in studying Alzheimer's disease--and testing potential therapies--have contained only amyloid plaques.

Then Dr. Michael Hutton of the Mayo Clinic in Jacksonville, Florida was able to engineer a line of mice that developed tangles, but not plaques.

Now, crossbreeding of the two strains has produced mice that develop both plaques and tangles, Hutton reported. And the tangles found in the brains of this new strain of mice were much more numerous, suggesting that the amyloid-beta peptide or a related protein may be involved in the formation of tangles.

"These results indicate that (the amyloid protein) influences the formation of neurofibrillary tangles," Hutton reported. "The interaction . . . in these mice supports the hypothesis that a similar interaction occurs in Alzheimer's disease."

Another study in Science by researchers at the University of Zurich also points to a link between plaques and tangles.

Dr. Roger M. Nitsch reported that after injecting amyloid-beta bits into the brains of mice, the mice developed five times more tangles than mice that did not receive the injection. Interestingly, most of the tangles occured not at the site of the injection, but in a part of the brain linked to the injection site by long nerve-cell projections called axons.

Dr. Virginia M. Y. Lee of the University of Pennsylvania, in an accompanying editorial, concludes that the "discovery of possible interactions between amyloid-beta deposits and tau tangles and the availability of genetically engineered mouse models containing both pathologies will facilitate efforts to develop more effective Alzheimer's disease therapies."

Other sources: Science