TUESDAY, May 21, 2002 (HealthDayNews) -- A protein that heralds heart trouble may cause problems in the brain as well.
The molecule -- called high-sensitivity C-reactive protein -- may be linked to as much as a threefold increased risk of cognitive loss such as Alzheimer's disease and dementia related to vessel damage, says a new study of Japanese-Americans.
C-reactive protein is an echo of inflammation that has been gaining prominence as a potentially critical measure of blood vessel damage. Studies have shown that people with the highest concentrations of the substance are between three and four times more prone to heart and vessel disease than those with low amounts.
However, as the latest work suggests, whatever vessel distress C-reactive protein reflects isn't limited to the plumbing around the heart, but extends to the pipes that feed the brain. A report on the findings appears in the August issue of the Annals of Neurology, which posted the paper this week on its Web site.
The study falls out of an ongoing analysis of thousands of Japanese-American men living in Hawaii. Researchers in Austria and the United States compared C-reactive protein levels with dementia risk in 1,050 volunteers in the project, which has been going on for more than 35 years. Of those, 836 had no signs of cognitive trouble, while 214 had been diagnosed with either probable Alzheimer's disease or dementia related to vessel damage.
As part of the initial study, the men had blood drawn between 1968 and 1970.
Compared with men with levels of the protein in the lowest quarter, those with more blood protein had triple the odds of being demented roughly 25 years later, the researchers found. The risk of vascular dementia -- though not Alzheimer's -- increased somewhat as C-reactive protein levels climbed.
Factors such as a history of strokes, diabetes and cardiovascular disease boosted the risk of both elevated C-reactive protein and dementia. However, the effect of the protein remained strong even when the researchers accounted for these and other variables, including level of education and smoking status, known to worsen cognitive loss with age.
Lenore Launer, an epidemiologist at the National Institute on Aging, which funded the study, says it appears C-reactive protein is a proxy for brain vessel harm that doesn't show up as strokes or other obvious tip-offs.
"If we had better indicators of vascular damage in the brain specifically, then maybe we would find that the association [between the protein and dementia] is no longer" evident, says Launer, a study co-author.
Although the researchers looked only at men, studies of C-reactive protein and heart disease have found no glaring gender differences, Launer adds, so it's plausible the link to dementia would also apply to women.
Dr. Lon White, an aging medicine specialist at the University of Hawaii in Honolulu and head of the long-term study, says the latest results support the notion that Alzheimer's disease and other forms of dementia are closely connected.
"Insults that lead to vascular disease may exacerbate Alzheimer's, and contribute to total brain injury," White says.
Researchers have come to see the brain as vulnerable to "hardware" damage, such as strokes and head trauma, and "software" trouble, such as a lack of education, White says. Either can sap the mind's reserves. And since these reserves ebb with time, earlier deficits may lead to debilitating losses later in life.
"The individual mechanisms may be very independent and discrete, but patients may get sicker earlier or later depending on the combination," White says.
What To Do: For more on C-reactive protein, try MEDLINEplus. To learn more about Alzheimer's disease, try the Alzheimer's Association.
