Enlarged perivascular spaces, which are commonly seen on brain MRIs in older adults, have important associations with worse cognitive performance, particularly information processing speed and executive function, according to a new study that challenges historical consideration that perivascular spaces are a harmless imaging marker.
Enlarged perivascular spaces are fluid-filled spaces around the cerebral small vessels seen on brain MRIs. In comparison to common markers of small vessel disease, results show a more frequent association between enlarged perivascular spaces and cognition than expected.
Computer tomography of human brain, from base of the skull to top. Image credit: Department of Radiology, Uppsala University Hospital via Wikimedia, CC0 Public Domain
And, while some small vessel disease markers overlap in connection to cognition, these enlarged spaces appear to reflect unique pathways of injury that were distinct from the other markers.
The study, which looked at older adults who have not yet developed dementia, offers evidence that small vessel disease is not a singular construct. Rather, it is likely a diverse construct in which multiple neuroimaging markers of small vessel disease reflect distinct pathways of injury as well as early or late features of severity, said Angela Jefferson, PhD, professor of Neurology, director of the Vanderbilt Memory and Alzheimer’s Center at Vanderbilt University Medical Center, and senior author of the study published in Neurology.
“Enlarged perivascular spaces contributed to adverse cognitive health through a unique pathway of injury that was distinct from the other markers. That result was unexpected and emphasizes that enlarged perivascular spaces deserve further study. Our work shows they are not benign,” said Jefferson.
Cerebrovascular changes, including small vessel disease, are common in aging and contribute to unhealthy memory loss and dementia. In particular, cerebrovascular disease contributes to more than 80 percent of all autopsy-confirmed cases of dementia and is the most common pathology to co-occur with Alzheimer’s disease, which is the most frequent form of dementia among older adults.
For example, among aging adults, the detection of one or two microinfarcts at autopsy likely indicates over 1,000 total microinfarcts exist throughout the brain.
The study was designed to better understand how several markers of small vessel disease connect to cognition and what these changes mean for older adults when detected on brain scans.
The authors looked at whether each of the imaging markers related to different cognitive activities, such as language, memory, visuospatial skills, information processing speed and executive functioning, and if the markers reflected a common or unique pathway of injury.
The researchers focused on well-studied markers of small vessel disease, including white matter hyperintensities, infarcts, and microbleeds, as well as enlarged perivascular spaces, which have received less attention in scientific literature.
The most frequent associations in the study linked white matter hyperintensities and cognition, including language, information processing speed, executive functioning and visuospatial skills.
Unexpectedly, for the researchers, the next most frequent links were between enlarged perivascular spaces and information processing speed and executive functioning.
“These results are important for any clinician or scientist who works in aging. Many of these small vessel disease markers are due to common vascular risk factors for cardiovascular disease, such as high blood pressure or diabetes. We know these conditions can be prevented and treated, which means small vessel disease and its impact on abnormal cognitive changes can be prevented,” said Jefferson.
Source: Vanderbilt University