What Is Alzheimer's Disease?

Alzheimer's disease is a progressive, irreversible brain disorder that slowly destroys memory, thinking skills, and the ability to carry out simple daily tasks. It is the most common cause of dementia in older adults, though it is not a normal part of aging.

What Happens in the Brain 

The disease is characterized by physical changes in the brain tissue that lead to the buildup of abnormal proteins: 

  • Amyloid Plaques: Clumps of a protein called amyloid build up between brain cells.
  • Tau Tangles: Twisted fibers of another protein called tau build up inside the cells. 
These protein buildups damage and eventually destroy neurons (nerve cells) in the brain, causing the tissue to shrink. 


Key Symptoms

Symptoms develop gradually over many years and worsen over time. Early signs are often mistaken for normal aging, but they eventually become severe enough to disrupt daily life: 

  • Memory Loss: Frequently forgetting recent conversations, appointments, or repeatedly asking the same questions.
  • Cognitive Decline: Trouble managing finances, making sound decisions, or understanding abstract numbers.
  • Disorientation: Getting lost in familiar places or having difficulty knowing what day or season it is.
  • Behavioral Changes: Unexplained mood swings, increased confusion, withdrawal from social activities, and depression. 

Diagnosis

While there is no single test for Alzheimer's and no known cure, a combination of methods—including brain scans (MRI, PET), memory assessments, and blood tests—is used to make an accurate diagnosis.