Degeneration of dementia with Lewy bodies measured by diffusion tensor imaging.

Dementia with Lewy bodies (DLB) is the second most common form of dementia. It is thought to involve impairment of the visual association area. In this study, we applied diffusion tensor imaging (DTI) to examine the microstructural interruption of visual association areas in patients with DLB. The DTI metrics of three visual association fibres - the inferior longitudinal fasciculus (ILF), visual pathway, and splenial fibres - were compared between 14 patients with DLB and 13 healthy subjects. The fractional anisotropy value of the ILF was significantly lower in patients with DLB than in healthy subjects. The difference in the mean diffusivity value of ILF was at trend level. The lambda(2),(3) of ILF were significantly lower in patients with DLB; however, there was no difference in lambda(1). DTI metrics of the visual pathway and splenial fibres showed no differences between the groups. Our results showed degeneration of the ILF, which is responsible for visuospatial cognition. ILF dysfunction may influence the clinical features in DLB.