Pete Hannon, MD

King KS, Peshock RM, Rossetti HC, McColl RW, Ayers CR, Hulsey KM, et al. (HCR)Effect of Normal Aging Versus Hypertension, Abnormal Body Mass Index,and Diabetes Mellitus on White Matter Hyperintensity Volume. Stroke. 2013

“White matter changes consistent with non-specific chronic microvascular disease.” These words, or something similar, grace a very large percentage of our MRI reads, and have caused much consternation to patients, not to mention any number of Neurology referrals. When it comes to white matter changes, how much is too much? What is normal?

To help answer these questions, authors Dr. Kevin King and colleagues have compared age-related differences in MRI white matter hyperintesity (WMH) volume in healthy individuals vs. those with comorbid hypertension, abnormal BMI and/or diabetes. From 2007 to 2009, MRIs of 2011 participants were evaluated for WMH volume. Of that number, 285 lacked the pre-specified comorbidities (relative healthy controls), 973 had hypertension, 245 had diabetes, and 1578 had abnormal BMI. Participants were subgrouped by ethnicity, sex and age. Per authors, there was a linear association between age and a greater log WMH volume. Before age 50 there was no significant difference between the two groups, however after age 50 a more rapid increase in WMH volume was noted in the group with comorbidities (p=0.0008).

Within the scope of the subgroups selected, it is evident that “normal” aging carries with it some increase in WMH burden. Unfortunately within the control group, there is no mention of smoking history, cholesterol levels, or other cardiovascular risk factors, and the two groups had significant difference at baseline regarding sec and race, making it difficult to generalize what WMH volume can be attributed to normal aging, free of other comorbities. The marked cutoff after age 50 does highlight the role that HTN, DM and obesity to play in WMH burden, however, especially as we age.

It’s commendable that this study aims to find what WMH can be attributed to normal aging, and that which may be attributed to other causes. In the future it will be nice to have specific criteria for what burden of WMH burden can be considered “within normal limits.”