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

• White matter damage was quantified using the Fazekas rating scale.
• Measures of amyloid were measured using positron emission tomography.
• There was a greater severity of damage in demented individuals.
• White matter damage significantly predicted dementia after controlling for amyloid.
• There is a clinical utility to using the Fazekas scale in addition to amyloid levels.

Background and purposeElevated 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 methodsThe 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.ResultsLevels 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.ConclusionsThe 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.