May 28, 2010
A blood protein commonly associated with heart disease and inflammation is also linked to problems with thinking, a new study found. The findings further strengthen the growing links between heart health and brain health and point to a possible role of inflammation in contributing to the thinking problems of Alzheimer’s disease.
The protein, called C-reactive protein, or CRP, often signals that there is inflammation somewhere in the body when CRP levels are higher than normal. The more CRP a person has, the greater the likelihood of heart and blood vessel disease, heart attacks and strokes. These diseases are believed to involve inflammation within artery walls. Other studies have also linked high inflammation to an increased risk of Alzheimer’s and other forms of dementia, though the relationship still needs to be made clearer.
The new study was published in the journal Neurology, from the American Academy of Neurology. Researchers in Germany found that those with high CRP levels had brain changes associated with problems in so-called executive function, or the ability of the brain to plan and execute tasks and behave in an appropriate manner.
High levels of CRP, however, were not associated with problems in memory or language skills, which are often a prominent feature of Alzheimer’s disease. CRP did seem to correlate with defects in the brains frontal lobes, which are involved in thinking.
For the study, scientists examined 447 men and women, average age 63, who were mentally intact and free of symptoms of Alzheimer’s. They underwent a type of brain scan known as DTI, for diffusion tensor imaging, to look for defects in the brain’s white matter. They also completed tests to measure verbal recall and memory (the ability to use words) and executive function (planning and making decisions).
The study found that people with higher levels of CRP did worse on executive function tests. Overall, the average time to complete a test of executive function was 85 seconds. Those with the highest levels of CRP took an average of seven seconds longer to complete the test than those with the lowest levels of the protein. The brain changes measured with DTI were equivalent to 12 years of aging for those with the highest levels of CRP compared to those with the lowest levels.
More research is required to determine how inflammation may damage the brain and possibly contribute to Alzheimer’s disease. High levels of inflammation are known to damage blood vessels, including those in the brain. But even when the brain shows signs of damage, it does not mean someone will exhibit memory loss and other thinking problems related to Alzheimer’s.
“The use of aspirin and statin drugs as well as physical activity and controlling weight can help lower CRP levels in the body, but our analyses did not consider whether therapy would be effective or not,” said study author Dr. Heike Wersching of the University of Münster in Germany.
Continuing research into inflammation, the brain and Alzheimer’s will, however, help us understand the underlying mechanisms of the disease and may one day help lead to effective treatments.
H. Wersching, MD; T. Duning, MD; H. Lohmann, PhD et al: "Serum C-reactive protein is linked to cerebral microstructural integrity and cognitive function." Neurology, Vol. 74, March 30, 2010, pages 1022-1029.
Ronald J. Killiany, PhD: "Are white matter signal abnormalities clinically relevant?" (editorial). Neurology, Vol. 74, March 30, 2010, pages 1014-1015.