Long Term Memory Loss Causes: Potential Risk Factors for Dementia

Research shows that age matters when it comes to risk factors of dementia and long term memory loss.

By Dr. Claudia Kawas

Unique Dementia Risks for the 90+ Population.jpg

Today, people age 90 and older make up 4.7 percent of the older population (people age 65 and older). By 2050, the number of people age 90 and older, commonly referred to in geriatric studies as the “oldest old,” is expected to increase to 10 percent of the older population. As lifespans rise, the changing demographics will impact our social, economic and health care systems—and lead to more people living with long-term memory loss. So why do we know nearly nothing about the oldest old?

Doctors and researchers in geriatric medicine have long treated seniors of all ages with the same standards of care. That means symptoms in 55-year-olds are addressed in the same way they might be for 98-year-olds. We’ve been assuming one set of truths holds true across older age groups without evidence that the blanket approach is appropriate.

In 2003, I started the 90+ Study at the University of California, Irvine, to gather data to help improve the quality and length of life among the oldest old. After more than 10 years of research, we are proving that what is true for 55-year-olds simply doesn’t hold true for people 90 and up.

As an example, we can look at differences in dementia risk factors between the 55-plus and 90-plus communities. Numerous studies suggest that having high blood pressure earlier in life (around ages 55–70) is a risk factor for dementia later in life. But when we studied people in their late 80s and 90s, we found that high blood pressure is not a risk factor for dementia. In fact, we found that the oldest old who have normal or low blood pressure are actually at the highest risk for dementia. 

We have also found a very strong relationship in the oldest old between low oxygen saturation levels in their blood and the odds of having dementia. A quarter of the 90-plus participants we studied over the past 10 years had a saturation level of 93 percent or less, whereas a normal level would be between 98 percent and 100 percent. That low level is less common in other age groups. 

We don’t know exactly why these differences occur just yet, but that’s why this type of research is so important.

The fact is that when it comes to health care, age matters. We have always known that age mattered for the youngest generations, which is why standards of care are different for a 14-year-old, a 4-year-old and a 6-month-old. But somewhere along the way, we lost sight that age is just as important on the other end of the spectrum. To ensure this growing population of the oldest old is adequately cared for, we must continue to do research—and aging adults must continue to ask questions about their care. 

Claudia Kawas, M.D., is professor of neurology and neurobiology and behavior at the University of California, Irvine, and a geriatric neurologist and researcher in the areas of aging and dementia. 

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