The causes of Alzheimer’s disease (AD) are still not known, despite years of intensive research. According to the National Institute on Aging, causes may include genetic problems, lifestyle factors, elements in the environment, abnormal protein deposits on the brain, age, family history and problems with the immune system.
Alzheimer’s disease differs from other types of dementia with the presence of neuritic plaques (clusters of degenerating nerve endings) and neurofibrillary tangles (twisted fragments of proteins that clog nerve cells). However, doctors can only verify these changes by viewing the brain cells through a microscope during an autopsy.
Another factor related to the causes of AD is a protein called the tau protein. It supports the structure for brain neurons and researchers think it can damage neurons if it becomes altered. Because affected people are usually older than 65, age is thought to be a cause of Alzheimer’s disease, however AD is not considered to be a part of the normal aging process. Having a close family member with the disease, or genes such as APOE epsilon 4 allele, increases the risk of developing Alzheimer’s.
Mild cognitive impairment (MCI) may be associated with Alzheimer’s disease. This mild form of forgetfulness often precedes the onset of the disease, but people with MCI do not always develop Alzheimer’s.
Researchers also think issues related to lifestyle and heart health may be related to the causes of Alzheimer’s disease. Growing evidence suggests that that there is some association between cognitive disease and high blood pressure, high cholesterol, obesity and diabetes. A lack of social engagement and physical and mental activity that keep the brain stimulated may also be factors involved in AD.