Markers of Alzheimers dont doom you to dementia
Even if you discover that you have the first biological signs of Alzheimers, you are not doomed to develop the crippling dementia, a new study suggests. Just because you have amyloid [proteins] in the brain doesnt mean youre going to get dementia tomorrow. It doesnt mean youre going to get dementia in five years, said lead researcher Ron Brookmeyer. Hes a professor of biostatistics with UCLAs Fielding School of Public Health.
It could be many years, and it could be longer than your natural life expectancy, Brookmeyer added. For example, high levels of abnormal amyloid proteins in your brain or shrinkage of your brain each confer only a minimal risk of future dementia, a new statistical risk model indicates.
Further, a persons dementia risk is even lower if the amyloid or shrinkage is detected at a more advanced age, the study authors noted.
On the other hand, a persons risk does rise if early biological signs of Alzheimers start stacking up, the investigators found.
For instance, a 60-year-old man with high levels of amyloid protein has just a 23 per cent chance of developing dementia in his lifetime, while a 60-year-old woman has a 31 per cent risk, the researchers said.
Shrinking of specific brain regions confer similarly low lifetime dementia risks at age 60; about 23 percent for men and 30 per cent for women.
But if men or women have both high amyloid levels and brain shrinkage at age 60, their dementia risk increases to 34 per cent and 42 per cent, respectively, according to the report.
People face the most risk if they have high amyloid levels, brain shrinkage and early signs of mild cognitive impairment, the researchers explained. This impairment usually crops up as memory loss.
With all three signs present, 60-year-old men and women have a 93 per cent and 96 per cent risk of developing Alzheimers, respectively.
Age and life expectancy also play a strong role in Alzheimers dementia risk, Brookmeyer said.
Dementia risk decreases with age because its less likely a person will develop Alzheimers during their lifetime, he explained. But life expectancy also plays a part.
Females will generally have higher risks, because females have a longer life expectancy. With a longer life expectancy, theres more time for the preclinical disease to progress, Brookmeyer said.
For this study, the researchers analyzed data on just over 2,000 people who participated in two long-term studies on Alzheimers disease. These studies included scans for amyloid, brain shrinkage and cognitive impairment, all of which can be observed before a person falls victim to dementia.
This study could be considered good news for the 46.7 million Americans who carry some early signals of Alzheimers disease, Brookmeyer said.
It may actually provide some reassurance to people that despite testing positive on some screening tests, their chances of developing Alzheimers dementia may remain low, Brookmeyer said.
However, he noted that the model needs to be further refined to include other factors -- such as genetics -- that affect dementia risk.
James Hendrix, director of global science initiatives for the Alzheimers Association, agreed that its too early to take much hope from this study.
HealthDay
