New research, published in JAMA Neurology by Dr. Bruce Reed and colleagues, has found that vascular brain injury, resulting from high blood pressure or stroke, might be more significant at predicting cognitive impairment than amyloid plaque formation, which is traditionally associated with Alzheimer’s and other forms of dementia. The study, conducted by researchers at the Alzheimer’s Disease Research Center at UC Davis, examined 61 elderly patients with varying degrees of impairment; 30 participants were considered ‘normal’ and exhibited no deficiencies, 24 were cognitively impaired and seven were diagnosed with dementia. Participants in the study underwent an MRI to measure vascular brain injury and a PET scan with carbon-11 Pittsburgh Compound B (PiB) to determine the extent of beta amyloid deposition (plaques).
Vascular brain injury appeared as infarcts (areas of dead brain tissue resulting from inadequate blood flow) and “white-matter hyperintensties” on MRI scans while the extent of amyloid plaque formation on PET scans was determined using PiB-PET. Researchers found 34 patients were positive for infarcts while 27 appeared negative. Twenty nine subjects were found to be PiB positive and the remaining 32 were negative
The presence of brain infarcts, especially when originating in the cortical and sub-cortical gray matter, negatively impacted the patient’s memory and ability to problem solve and organize. Interestingly, the level of amyloid deposits in the brain did not appear to correlate with changes in memory or function. These results correlated with previous research conducted at the Oregon Health and Science University (OHSU) that examined the connection between white-matter hyperintensties and the onset of cognitive impairment. Researchers found an increase in white-matter hyperintensties preceded the onset of mild cognitive impairment in patients by ten years, well before any clinical signs of dementia would appear.
Additionally, when Reed and colleagues examined the correlation between vascular brain injury and the formation of amyloid plaque, they found that vascular brain injury carried no increased risk for amyloid plaque formation. Reed said, “What this study says is that doctors should think about this in a little more complicated way. They should not forget about cerebrovascular disease, which is also very common in this age group and could also cause cognitive problems. Even if a person has amyloid plaques, those plaques may not be the cause of their mild cognitive symptoms.”
Making this distinction is significant due to the huge interest in detecting Alzheimer’s before a patient exhibits clinical symptom. This study is also particularly important in light of a new MRI technique that has been developed at the University of Pennsylvania which allows clinicians to differentiate between Alzheimer’s and another type of dementia. All of these new and exciting studies are helping push us closer to translating research advances into improved diagnostic and treatment plans for patients.