The effects of white matter hyperintensities and amyloid deposition on Alzheimer dementia

BACKGROUND AND PURPOSE Elevated levels of amyloid deposition as well as white matter damage are thought to be risk factors for Alzheimer Disease (AD). Here we examined whether qualitative ratings of white matter damage predicted cognitive impairment beyond measures of amyloid. MATERIALS AND METHODS The study examined 397 cognitively normal, 51 very mildly demented, and 11 mildly demented individuals aged 42-90 (mean 68.5). Participants obtained a T2-weighted scan as well as a positron emission tomography scan using (11)[C] Pittsburgh Compound B. Periventricular white matter hyperintensities (PVWMHs) and deep white matter hyperintensities (DWMHs) were measured on each T2 scan using the Fazekas rating scale. The effects of amyloid deposition and white matter damage were assessed using logistic regressions. RESULTS Levels of amyloid deposition (ps < 0.01), as well as ratings of PVWMH (p < 0.01) and DWMH (p < 0.05) discriminated between cognitively normal and demented individuals. CONCLUSIONS The amount of amyloid deposition and white matter damage independently predicts cognitive impairment. This suggests a diagnostic utility of qualitative white matter scales in addition to measuring amyloid levels.