A groundbreaking project called the “ninety plus study has uncovered new pages of the dementia story.

Dr. Claudia Kawas of the University of California, Irvine and other scientists are studying 14,000 individuals 90 and older who lived at the retirement community Leisure World. Leisure World kept a detailed medical history of all of their residents. These individuals and their medical histories are a scientist’s dream and provide valuable clues into what causes dementia and how it can be avoided.

The “ninety plus study” has turned the way we think about Alzheimer’s dementia upside down.

Alzheimer’s can only be definitively diagnosed in the brain after death. When looking at the brain postmortem Doctor’s always look for the plaques and tangles in the brain that are thought to be the telltale signs of Alzheimer’s disease.

However, Kawas and fellow scientists found that many diagnosed with Alzheimer’s didn’t have any plaques or tangles when their brain was inspected after death.

The scientists found instead tiny microscopic strokes called microinfarcts. These strokes are so small that they are undetectable during life even with the use of an MRI machine. A person may have hundreds and even thousands of these strokes without even noticing it. Overtime their dementia worsens. This type of dementia is called vascular dementia.

Researchers found that over 40 percent of the time what doctor’s thought was Alzheimer’s was in fact vascular dementia caused by hundreds of these undetectable micro-strokes.

The scientists also found that some of those studied who never experienced symptoms of Alzheimer’s disease in life were found to have plaques and tangles in their brain after death. Kawas is puzzled by these new findings.

Several possibilities exist. “Perhaps plaques and tangles have nothing to do with Alzheimer’s. Or perhaps plaques and tangles do cause cognitive problems, but a 90 year old who didn’t develop thinking problems has some way of getting around the plaques and tangles that the rest of us would like to know about,” said Dr. Kawas.

The researchers were particularly interested in two of the Leisure World study participants who still had strong cognitive skills and had not developed dementia. A new type of pet scan can detect plaques and tangles in the living and found that one of these two participants had plaques and tangles in his brain. Although the pet scan found plaques and tangles he is mentally sharp and alert with no cognitive decline. The researchers are excited to work with him and discover his secrets. Perhaps he is the key to finding a cure for Alzheimer’s.

To learn more watch the 60 Minutes special on the ninety plus study.”

New research is changing the way we think about Alzheimer’s disease.