The underlying causes of Alzheimer's disease are not fully understood, but a good deal of evidence points to the accumulation of β-amyloid, a protein that's toxic to nerve cells. β-amyloid -- a toxic protein known to accumulate in the brains of most Alzheimer's disease patients -- is formed by several enzymes, including BACE1. Researchers have now found that BACE1 does more than just help produce β-amyloid -- it also regulates another cellular process that contributes to memory loss. This is important information for drug makers looking to target BACE1 to prevent or treat Alzheimer's disease.