Alzheimer’s disease has been associated for over 100 years with two different types of brain lesions, the beta-amyloid plaques and the tau tangles, both discovered by Dr. Alzheimer himself.

…But it seems that living with plaques and tangles, doesn’t always lead to cognitive impairment.

At least this is what a team from Northwestern University in Chicago recently suggested.

They studied the brain of 8 individuals with superior memory who lived to be at least 90 years old.

In 3 cases, brains contained widespread plaques and tangles that would have normally been associated with full-blown Alzheimer’s symptoms.

A similar observation was made a few years ago in what is known as the « 90study » which studied the brains of Americans aged 90 years or older.

Autopsies revealed that intermediate or high level Alzheimer’s disease pathology was found in about a third of people without dementia or cognitive impairment in advanced old age.

According to the lead investigator from Northwestern University, these observations suggest that unknown factors protect the brain against Alzheimer’s pathology. These factors could either have a genetic origin, or could also be associated with the lifestyle of these elderly people.

For instance, higher education, social engagement, and the maintenance of cardiovascular health are thought to be factors that provide the brain with a cognitive reserve. This reserve might allow some individuals to tolerate a substantial amount of Alzheimer’s disease pathology without leading to memory impairment.

Research teams around the world are now engaged in epidemiological studies to determine which of several risk and protective factors are the best candidates for improving our ability to prevent symptoms of the disease.