Why Some People Get Alzheimer’s and Others Don’t

Many people who don't develop dementia are nonetheless discovered after their deaths to have the brain lesions associated with Alzheimer's disease.

It has been a surprise in Alzheimer’s disease research that a substantial number of people who never had dementia are discovered after their deaths to have the kinds of brain lesions associated with the disease. Dr. Juan Troncoso, a researcher at the Brain Resource Center at Johns Hopkins University, says in Big Think's Breakthroughs series that this is evidence that some individuals are able to resist the onset of Alzheimer’s.


What these individuals are resilient against is the toxic buildup in the brain of a fibrous protein called amyloid. This material, says Dr. Samuel Gandy of Mount Sinai Hospital, is made by cells throughout the body, throughout one's life, largely to no effect—until a certain point.

"For reasons we don’t understand, in certain regions of the brain, it changes its shape," says Gandy. The amyloid proteins form clumps that are poisonous to nerve cells. This poisoning of the brain from amyloid—known as the amyloid hypothesis—is a prevailing theory as to how the disease dissolves neurons, clogging the brain with the debris of dead cells. This, in turn, leads to dementia and eventually to death.

Those individuals who have been found with amyloid buildups in the brain but without dementia are, at least for a time, able to resist this amyloid toxicity, says Gandy. This happens through a system where the brain compensates, engaging other, new and more parts of its structure to perform a task which once took a localized part of the brain. 

Researchers are now looking for more hallmarks of resilience against the amyloid toxicity of Alzheimer’s disease. For example, imaging studies show evidence that the hippocampus in individuals who are able to resist the disease is generally larger, says Troncoso. Larger brain cells in some of those without dementia also signals a potential source of resiliency, says Gandy.

Short of an outright cure, building resiliency might eventually lead to therapies that delay the onset of dementia. "If we can identify what are the mechanisms to do that, it may contribute to prevent or to alleviate the disease," says Gandy.

The views expressed here are solely those of the participants, and do not represent the views of Big Think or its sponsors.

​There are two kinds of failure – but only one is honorable

Malcolm Gladwell teaches "Get over yourself and get to work" for Big Think Edge.

Big Think Edge
  • Learn to recognize failure and know the big difference between panicking and choking.
  • At Big Think Edge, Malcolm Gladwell teaches how to check your inner critic and get clear on what failure is.
  • Subscribe to Big Think Edge before we launch on March 30 to get 20% off monthly and annual memberships.
Keep reading Show less

Herodotus’ mystery vessel turns out to have been real

Archeologists had been doubtful since no such ship had ever been found.

(Christoph Gerigk/Franck Goddio/Hilti Foundation)
Surprising Science
  • In 450 BCE, Greek historian Herodotus described a barge that's never been found.
  • When the ancient port of Thonis-Heracleion was discovered, some 70 sunken ships were found resting in its waters.
  • One boat, Ship 17, uncannily matches the Herodotus' description.
Keep reading Show less

Horseshoe crabs are drained for their blue blood. That practice will soon be over.

The blood of horseshoe crabs is harvested on a massive scale in order to retrieve a cell critical to medical research. However, recent innovations might make this practice obsolete.

Credit: Business Insider (video)
Surprising Science
  • Horseshoe crabs' blue blood is so valuable that a quart of it can be sold for $15,000.
  • This is because it contains a molecule that is crucial to the medical research community.
  • Today, however, new innovations have resulted in a synthetic substitute that may end the practice of farming horseshoe crabs for their blood.
Keep reading Show less

Jordan Peterson on Joe Rogan: The gender paradox and the importance of competition

The Canadian professor has been on the Joe Rogan Experience six times. There's a lot of material to discuss.

Personal Growth
  • Jordan Peterson has constantly been in the headlines for his ideas on gender over the last three years.
  • While on Joe Rogan's podcast, he explains his thoughts on the gender differences in society.
  • On another episode, Peterson discusses the development of character through competition.
Keep reading Show less