Researchers from the Yale University School of Medicine have found a protein that is the missing link in the complicated chain of events that lead to Alzheimer`s disease.

Researchers also found that blocking the protein with an existing drug can restore memory in mice with brain damage that mimics the disease.

Stephen Strittmatter, the Vincent Coates Professor of Neurology and senior author of the study, said that the new discovery has given them hope that they e can find a drug that is going to work to lessen the burden of Alzheimer`s.

In earlier work, Strittmatter`s lab showed that the amyloid-beta peptides, which are a hallmark of Alzheimer`s, couple with prion proteins on the surface of neurons. By an unknown process, the coupling activates a molecular messenger within the cell called Fyn.

In the new study, the team revealed the missing link in the chain, a protein within the cell membrane called metabotropic glutamate receptor 5 or mGluR5.

When the protein is blocked by a drug similar to one being developed for Fragile X syndrome, the deficits in memory, learning, and synapse density were restored in a mouse model of Alzheimer`s.

The findings have been reported in the journal Neuron.