Changes to the lateral geniculate nucleus in Alzheimer's disease but not dementia with Lewy bodies

Abstract

AimsComplex visual hallucinations occur in 70% of dementia with Lewy bodies (DLB) cases and significantly affect patient well‐being. Visuo‐cortical and retinal abnormalities have been recorded in DLB and may play a role in visual hallucinations. The present study aimed to investigate the lateral geniculate nucleus (LGN), a visual relay centre between the retina and visual cortex, to see if changes to this structure underlie visual hallucinations in DLB.MethodsFifty‐one [17 probable DLB, 19 control and 15 probable Alzheimer's disease (AD)] cases were recruited for a functional magnetic resonance imaging study, in which patients' response to a flashing checkerboard stimulus was detected and measured in the LGN, before comparison across experimental groups. Additionally, post mortem LGN tissue was acquired for a cross‐sectional study using 20 (six DLB, seven control and seven AD) cases and analysed using stereology. α‐Synuclein, phosphorylated tau and amyloid‐β pathology was also assessed in all cases.Results DLB cases did not significantly differ from controls on neuroimaging, morphometry or pathology. However, a significant increase in amyloid‐β pathology, a reduction in number of parvocellular neurones and magnocellular gliosis was found in AD cases compared with control and DLB cases.ConclusionsThese findings suggest that the early visual system is relatively spared in DLB, which implies that upstream visual structures may be largely responsible for the generation of hallucinatory percepts. The significance of the degeneration of the LGN in AD cases is uncertain.

Review: Clinical, neuropathological and genetic features of Lewy body dementias

“…Pathology of the lateral geniculate nucleus showed no significant differences between DLB with VH and AD. However, AD cases had significantly more Aβ, less parvocellular neurons and had magnocellular gliosis compared to controls and DLB . Results from the study of the superior colliculus showed reduced neuronal densities in DLB in the stratum griseum intermedium compared to AD and controls .…”

Retinal Microperimetry: A Useful Tool for Detecting Insulin Resistance-Related Cognitive Impairment in Morbid Obesity

“…By contrast, the superior colliculus and the parietal and frontal cortex play an essential role in gaze fixation. There is evidence that both the geniculate body and the superior colliculus are affected by AD [42][43][44].…”

Specific patterns of neuronal loss in the pulvinar nucleus in dementia with lewy bodies

“…Neuropathological and physiological studies have demonstrated changes in the retina in DLB. However, the lateral geniculate nucleus (LGN), the primary afferent visual relay structure between the retina and the primary visual cortex, is spared in DLB compared with AD, suggesting that visual hallucinations in DLB may be facilitated by pathological changes in other parts of the visual system. In contrast to the LGN, α‐synuclein pathology was found throughout the pulvinar but was particularly marked in the medial pulvinar.…”

“…Images were taken within the dissector frames and analyzed using an ImagePro Plus v.4.1 image analysis system (Media Cybernetics, Bethesda, MD. Using previously published techniques, the mean percentage area of immunopositivity was determined by standardizing red‐green‐blue thresholds per antibody and applying these to all sections per case. Each case thus had a mean value generated per antibody across all sections analyzed.…”