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Brain Matter and Alzheimer's

Not Just Amyloid: White Brain Matter and Alzheimer's Disease

A new study published in the February 18, 2013 online version of The Journal of the American Medical Association – Neurology, agrees with a growing body of evidence indicating that cerebrovascular disease of the small vessels contributes to the development of Alzheimer's disease (AD). This study revealed that elevated WMHs (total white matter hyperintensities), as shown on an MRI scan, independently predict a diagnosis of Alzheimer's disease. The same is true of the brain amyloid tracer Pittsburgh compound B (PIB), which is measured by PET (i.e. positron emission tomography) scans.

These specific findings of this study suggest that while amyloidosis (a group of serious, rare diseases resulting from abnormal protein deposits) is required for an Alzheimer's disease diagnosis, it may not be enough to result in the development of dementia. In fact, total white matter hyperintensities may be another important dementia contributor.

Research Find Link between Alzheimer's Disease and Vascular Diseases

According to one of the study authors, a lot of research data that is being released at the moment clearly indicates the important relationship between Alzheimer's and vascular diseases. In the past, medical experts were not aware that there was a vascular component associated with Alzheimer's disease. Alzheimer's was only thought to be a condition of microscopic neural plaques and tangles. Now vascular lesions are also considered to be important factors.

Study researchers from Columbia University in New York utilized a 2003 Alzheimer's disease database. They obtained statistical information from 21 normal control patients, 59 patients with mild cognitive impairment, as well as 20 individuals with a clinical diagnosis of Alzheimer's. In addition, investigators downloaded data from PIB-PET scans and examined volumes of WMHs as seen on participants' MRI scans.

WHMs and Amyloid Related to Diagnosis of Alzheimer's

Findings of this research indicated that WHMs and amyloid were equally related to a diagnosis of Alzheimer's disease. In addition, these two factors were equal predictors of which mildly cognitively impaired participants would ultimately progress on to a diagnosis of Alzheimer's. Since risk factors for total white matter hyperintensities are controllable, these findings suggest that there are various ways to potentially prevent Alzheimer's disease in patients who have amyloid deposits.

The 59 participants who had mild cognitive impairment were followed up for approximately 30 months after the study's completion and eventually 37 percent developed Alzheimer's disease. When these 59 patients' data was analyzed in terms of their high or low WMH volume and PIB positivity, researchers realized that both factors were significantly predictive of future Alzheimer's development.

Researchers are still unsure exactly how WMHs and amyloid are connected. However, these results suggest that if patients have a lot of WMHs, they will also have a lot of amyloid within their brains. This fact is not a definitive indicator that these two factors are related, mechanically speaking.

Conclusions

In light of the findings of this study, it appears that it may be very important to control WMH risk factors. These risk factors are basically the same as stroke risk factors such as heart disease, hypertension, obesity, diabetes, and/or smoking. The study's lead researcher states that while it is still not completely clear if preventing the accumulation of WMHs and/or controlling vascular risk factors actually prevents the onset of Alzheimer's, there is certainly growing evidence suggesting that controlling vascular factors could at minimum reduce the risks, possibly delay onset and perhaps lessen the severity of Alzheimer's disease symptoms.

Resources:

http://www.sciencedaily.com/releases/2013/02/130219172231.htm

http://www.medscape.com/viewarticle/779690

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