Together with comparatively better understood diseases such as AIDS and Ebola virus, Alzheimer's disease is one of the three plagues of the late twentieth century.

Alzheimer's disease is characterized by the deposition of plaques and 'tangles' composed of beta-amyloid protein in the cells of the brain. Amyloid deposits appear to be inherently poisonous to cells. Although the molecular mechanisms involved in cell death are unclear, it is this toxic effect which gives the 'spongiform encephalopathies' their name, due to the characteristic holes seen in thin sections of affected brain tissue under a microscope. The holes are caused by the death of both neurons and their supporting framework of glial cells, which actually make up the structure of the brain. When this loss of cells affects the cerebral cortex, the brain shrinks perceptibly and higher cognitive abilities are progressively lost.

© AJC 1997.