Neurology: MR links midlife vascular risk factors and brain aging

Image source: Cedars-Sinai Medical Center

MRI exams of midlife adults revealed that hypertension, diabetes, smoking and obesity were linked with accelerated vascular brain injury and global and hippocampal atrophy, according to a study published online Aug. 2 in Neurology. The study found the risk factors were associated with a decline in executive function a decade later.

Previous research has suggested that exposure to vascular risk factors in midlife may increase risk of dementia. However, their impact on structural brain aging and cognitive performance in individuals without dementia was unclear.

To improve understanding of the links between vascular risk factors and risk of dementia, researchers designed a study to examine MRI markers of structural brain aging and performance on neuropsychological tests among a cohort of 1,352 participants from the prospective Framingham Offspring Cohort Study.

Participants in the study had undergone brain MRI and neuropsychological tests assessing memory and executive function between 1999 and 2005, and subsequent exams for this group were performed between 2005 and 2007.

MRI markers included lower total brain volume and hippocampal volume as well as other markers.

“All measures of change in MRI markers of brain aging were significantly correlated with each other and with change in verbal memory and executive function,” reported Stephanie Debette, MD, PhD, of the department of neurology at the Boston University School of Medicine, and colleagues.

The researchers found that hypertension and increasing systolic blood pressure correlated with a more rapid increase in white matter hyperintensity volume, and worsening performance in executive function a decade later.

Midlife diabetes was significantly associated with a greater annual increase in total hippocampal volume, a surrogate marker of accelerated hippocampal atrophy. Meanwhile, midlife smoking was linked with a greater annual increase in total hippocampal volume and decrease in total brain volume. Another key finding was that increasing waist-to-hip ratio was linked with an increased risk of marked decrease in total brain volume.

“Moreover, changes in brain structure were significantly associated with decline in both memory and executive function,” offered the authors.

Debette et al noted that interventional studies are required to assess any causative link between midlife vascular risk factor exposure and changes in structural brain aging and cognitive decline. However, they added, the findings are suggestive. Nonetheless, they urged caution, explaining that vascular risk factors are highly correlated with each other, which makes it difficult to uncover individual effects.

There are multiple strengths to the study, including its population-based setting, longitudinal design and availability of risk factor data in midlife. On the flip side, the sample was almost entirely Caucasian and had fewer risk factors than individuals unwilling or unable to undergo brain MRI or neuropsychological testing.

The researchers concluded with a pair of suggestions. Patients with midlife vascular risk factors should be targeted for primary prevention trials of dementia. Longitudinal intermediate markers based on brain MRI and cognitive testing, which can be measured in midlife, may be useful to screen treatments prior to evaluation in larger studies using clinical dementia as an endpoint.