The gamma secretase complex plays a major role in the creation of amyloid plaques, a typical characteristic of the brains of Alzheimer's patients. These plaques are abnormal accumulations of the beta-amyloid protein between the neurons. The gamma-secretase complex is also involved in the regulation of a series of essential proteins such as Notch, which plays a crucial role in the development of an embryo. This is why many of the medecines in development that act on the whole gamma-secretase complex run up against toxic side effects.We have studied the gamma-secretase complex in a variety of tissues and we were able to demonstrate that the complex assumes a different shape and function according to the tissue in which the secretase is active. The Aph1B gamma-secretase is a variant of the secretase complex thay cuts proteins specifically in the brain. Using a mice model, we have found that deactivating the Aph1B gamma secretase in Alzheimer mice leads to reduced formation of the plaques, without any harmful side effect. This raises hope for a drug that, for the first time, will succeed in stopping Alzheimer's disease.