Scientists believe that, for most people, Alzheimer’s disease results from a combination of genetic, lifestyle, and environmental factors that affect the brain over time.
Less than 5 percent of the time, Alzheimer’s is caused by specific genetic changes that guarantee a person will develop the disease.
While the causes of Alzheimer’s are not yet fully understood, its effect on the brain is clear. Alzheimer’s disease damages and kills brain cells. A brain affected by Alzheimer’s disease has many fewer cells and many fewer connections among surviving cells than does a healthy brain.
As more and more brain cells die, Alzheimer’s leads to significant brain shrinkage. When doctors examine Alzheimer’s brain tissue under the microscope, they see two types of abnormalities that are considered hallmarks of the disease:
*[connected this to plaques, tangles]*
Mayo Clinic Staff. “Alzheimer’s Disease: Overview.” Mayo Foundation for Medical Education and Research, 30 Dec. 2017, www.mayoclinic.org/diseases-conditions/alzheimers-disease/symptoms-causes/syc-20350447.