White matter lesions on magnetic resonance imaging in dementia with Lewy bodies, Alzheimer's disease, vascular dementia, and normal aging

Objectives-Alzheimer's disease and vascular dementia are associated with an increase in changes in white matter on MRT. The aims were to investigate w hether white matter changes also occur in dementia with Lewy bodies and to examine the relation between white matter lesions and the cognitive and non cognitive features of dementia with Lewy bodies, Alzheimer's disease, and v ascular dementia. Methods-Proton density and T2 weighted images were obtained on a 1.0 Tesla MRI scanner in patients with dementia with Lewy bodies (consensus criteria; n=27, mean age=75.9 years), Alzheimer's disease (NINCDS/ADRDA; n=28, mean age=77.4 years), vascular dementia (NINDS/AIREN; n=25, mean age=76.8 years) , and normal controls (n=26, mean age=76.2 years). Cognitive function, depr essive symptoms, and psychotic features were assessed using a standardised protocol. Periventricular hyperintensities (PVHs), white matter hyperintens ities (WMHs) and basal ganglia hyperintensities (BGHs) were visually rated blind to diagnosis using a semiquantitative scale. Results-Periventricular hyperintensities were positively correlated with ag e and were more severe in all dementia groups than controls. Total deep hyp erintensities scores (WMHs plus BGHs) were significantly higher in all deme ntia groups than controls and higher in patients with vascular dementia tha n those with dementia with Lewy bodies or Alzheimer's disease. In all patie nts with dementia, frontal WMHs were associated with higher depression scor es and occipital WMHs were associated with an absence of visual hallucinati ons and delusions. Conclusion-In common with Alzheimer's disease and vascular dementia, PVHs a nd WMHs were significantly more extensive in dementia with Lewy bodies than in controls. This overlap between different dementias may reflect shared p athological mechanisms. The link between frontal WMHs and depression and th e absence of occipital WMHs and psychotic symptoms has important implicatio ns for understanding the neurobiological basis of these symptoms.