People with enlarged fluid-filled spaces in the brain around small blood vessels may be more likely to develop dementia than people whose perivascular spaces are smaller, according to a new study published in Neurology®.

Perivascular spaces are involved in clearing waste and toxins from the brain and may play a role in the brain changes associated with aging.

The study, led by Dr Matt Paradise at UNSW Sydney’s Centre for Healthy Brain Ageing (CHeBA), involved 400 people with an average age of 80. Participants took tests of thinking and memory skills at the beginning of the study and again four years later. Researchers evaluated participants for dementia at the beginning of the study and again eight years later. The participants also had MRI brain scans to check for enlarged perivascular spaces in two areas of the brain. The top quarter of the people with the largest number of enlarged perivascular spaces, or the severe cases, were compared to those with fewer or no enlarged spaces, or the mild or absent cases.

"Severe perivascular space disease may be a marker for an increased risk of cognitive decline and dementia."

Dr Matthew Paradise, Study Author & Research Fellow at CHeBA

“More research is needed to understand how these enlarged spaces develop, as they could be an important potential biomarker to help with early diagnosis of dementia.”

Researchers found that people with severe cases in both areas of the brain were nearly three times more likely to develop dementia during the study than people with fewer or no enlarged spaces.

A total of 97 people, or 24%, were diagnosed with dementia during the study. Of the 31 people with severe cases in both areas of the brain, 12 people, or 39%, were diagnosed with dementia.

The people with severe cases in both areas of the brain or in just the area called the centrum semiovale were also more likely to have greater decline four years later on their overall scores on thinking and memory skills tests than the people with mild or absent cases.

The results remained after researchers adjusted for other factors that could affect either scores on tests or the development of dementia, such as age, high blood pressure and diabetes. The researchers also took into account other signs of disease in the small blood vessels in the brain, which can also be a sign of risk of dementia.

"These results suggest that there is an independent mechanism for the perivascular spaces as a biomarker of cognitive impairment and dementia apart from being a general marker of disease in the small vessels."

Dr Matthew Paradise

“For example, enlarged perivascular spaces may be a biomarker of impaired waste clearance in the brain.”

Co-author and Co-Director of CHeBA, Professor Perminder Sachdev, said that vascular abnormalities play a central role in the development of dementia in a large proportion of patients.

"Vascular abnormalities can manifest in many forms, and this study highlights the importance of looking at perivascular spaces, which have often been dismissed in the past as being simply normal age-related changes."

Professor Preminder Sachdev, Co-Author & CHeBA C0-Director

Limitations of the study include that tests of thinking and memory skills were taken at the beginning of the study and then only one more time during the study and that imaging data could have missed enlarged perivascular spaces in the brain.

The study was supported by the Australian National Health and Medical Research Council and the Josh Woolfson Memorial Scholarship