Cognitive impairment risk: White matter hyperintensity progression matters

OBJECTIVE: To determine whether white matter hyperintensity (WMH) progression rate is a better predictor of cognitive impairment risk than baseline WMH volume in healthy elderly individuals. METHOD: Ninety-eight cognitively intact elderly subjects were followed in the Oregon Brain Aging Study. Forty-nine had at least 3 brain MRIs and annual cognitive and neurologic assessments until diagnosed with persistent cognitive impairment (PCI). Brain, ventricular CSF (vCSF), intracranial volume (ICV), hippocampus, total WMH, periventricular (PV) WMH, and subcortical WMH volumes were measured. Cox proportional hazards survival analyses were used to assess cognitive impairment risk. RESULTS: After adjusting for age, apolipoprotein E4 status, incident hypertension, ICV, entry Mini-Mental State Examination, baseline hippocampus, and both baseline vCSF volume and rate of vCSF volume change, increased progression of total WMH volume (hazard ratio [HR] 1.84, 95% confidence interval [CI] 1.3-2.7, p = 0.0007) and PV WMH volume (HR 1.94, 95% CI 1.3-3.1, p = 0.001) conferred higher risk of PCI, whereas baseline WMH volumes did not. Every 1 mL/y increase in PV WMH volume was associated with a 94% increased risk of PCI. CONCLUSION: Progression of total and periventricular (PV) white matter hyperintensity (WMH) volumes are better predictors of persistent cognitive impairment (PCI) than baseline WMH burden. Greater PV WMH burden progression is associated with the development of PCI, a potential precursor to Alzheimer or vascular dementia. Identification of factors that decrease WMH accumulation over time is needed to maintain cognitive health in our growing elderly population.