CBS’s 60 Minutes aired a report on a 10-year study of the “oldest old” on Sunday, May 4. Known as the 90+ Study, researchers at UC Irvine have been following 1400 people over the age of 90 since 2003. They review their medical records and visit each participant every 6 months to assess their physical and cognitive functioning. The results are both fascinating and surprising.

Alzheimer’s Disease in those Over 90

The Study’s findings on dementia are startling. Contrary to popular belief, there does not appear to be any age at which one is no longer susceptible to dementia. The risk of developing dementia doubles every 5 years, and that risk continues for those over the age of 90.

Role of Plaques and Tangles

Plaques and tangles in the brain have long been considered the hallmarks of Alzheimer’s disease. However, the brain scans of the 90+ Study participants present a much more complicated picture:

•  50% of the participants who die without any symptoms of dementia have plaques and tangles in their brains.

• 40% of the participants who exhibit symptoms of dementia have no plaques or tangles in their brains.

Strokes and Blood Pressure

Frequently, the brain scans of participants with dementia but without plaques or tangles show evidence of multiple microscopic strokes.

High blood pressure is generally associated with a higher risk of stroke. However, in the cohort of those 90+, those with low pressure were more likely to develop dementia than those with higher blood pressure.

Implications

Dr. Claudia Kawas, the principal investigator of the 90+ Study, thinks that the causes of Alzheimer’s and other dementias are far more complex than the research community has acknowledged. Plaques and tangles are only part of the Alzheimer’s puzzle. Researchers will need to expand their thinking to identify other possible agents as well as protective factors.

Next steps

The National Institute of Aging has funded the 90+ Study and recently renewed its grant to UC Irvine for another 5 years.  Over this next funding period, the study will try to answer these questions:

•  Why do many of the oldest old remain cognitively intact even though their brains have plaques and      tangles?
•  Are there protective mechanisms in some people that compensate for the presence of plaques and  tangles?
•  What are the causes of cognitive decline of the oldest old who show no Alzheimer’s pathology?
• Are the factors that determine whether a person over 90 develops Alzheimer’s different from the factors that affect younger people?

You can read more about the 90+ Study, including its very interesting findings on longevity, here.  If you would like to watch the 60 Minutes segment (it is broken into 2 separate videos) and meet some of the research participants, you can do so here.