The exact cause or causes of AD are not fully understood. Researchers believe that AD is caused by a combination of genetic, lifestyle and environmental factors which over time affect the normal function of the brain. One of the significant unexplained mysteries of the disease is why it largely strikes older adults. At present, considerable research on brain aging is attempting to answer this question.
Experts believe that in AD certain brain proteins fail to function normally and disrupt the neurons which in turn produces a series of toxic events. Neurons become damaged, lose their connections to each other and eventually die. Much of this damage begins in the region of the brain that controls memory and over time neuron damage spreads to other regions of the brain. In the late stage of AD, the brain significantly shrinks
Considerable research on the causes of AD has focused on the role of two key proteins:
- Certain proteins, called Tau proteins, play a role in the neuron’s transport system to help carry nutrients and other essential materials. However, in AD the Tau proteins change shape and form different structures called neurofibrillary tangles. As a result, the tangles disrupt the transport system and become toxic to cells.
Image: This image depicts a healthy brain vs. a severe Alzheimer's brain. By the final stage of Alzheimer’s Disease, the brain tissue shrinks significantly. (Abnormal deposits of proteins form amyloid plaques and tau tangles throughout the brain. Once-healthy neurons stop functioning, lose connections with other neurons, and die. As more neurons die, additional parts of the brain are affected and begin to shrink. By the final stage of Alzheimer’s, damage is widespread, and brain tissue has shrunk significantly).