Why does Alzheimer's affect memory?

THAT'S THE WHY: Every 70 seconds, someone in the US is diagnosed with a new case of Alzheimer's disease. It is the most common form of dementia, an umbrella term for conditions that damage brain tissue and lead to progressive loss of brain function over time.

But why do people with Alzheimer’s disease gradually lose memory and motor function as the condition progresses?

Normally, the brain works by passing electrical and chemical signals along and between its estimated 100 billion neurons – long spindly brain cells that interconnect or “wire” with each other to form networks.

In Alzheimer’s disease this flow of information is disrupted as deposits of proteins and other molecules build up, and as the condition progresses, more brain cells become jammed and die.

There are two main types of deposit: sticky amyloid plaques that accumulate outside neurons and long stringy tangles of tau proteins that form within the cells.

The pathology usually follows a predictable pattern within the brain and deposits accumulate in the hippocampus, the brain’s memory and learning centre, explaining symptoms of forgetfulness and confusion. By the severe stages of the condition, the damage to brain tissue is widespread.

Current drug treatments may delay the progression of Alzheimer’s disease in an individual, and other strategies are also being developed, such as “vaccines” that target amyloid-beta protein to inhibit plaques from forming.