At this stage, there is no obvious clue in the environment. The great majority of the people live in the same rural area in the high plains of western Colombia. They are poor and not well-educated. Alternately, another gene could switch presenillin 1 on at an age that varies from person to person. Once the abnormal gene is turned on, researchers have only a sketchy idea of what happens.
Unaffected brains make the same protein, showing that it is something that the body needs.
Too much of it, however, forms plaques that surround connections between brain cells, preventing normal communications between its separate areas. Since not much difference exists between behavior and the condition of the brain in both early and conventional Alzheimer's, new information about the former may help solve mysteries of the latter. For example, Selkoe and his colleagues are looking for drugs that turn down the production of amyloid beta.