Neurofilament-immunoreactive neurons in Alzheimer's disease and dementia with Lewy bodies

Abstract

The cortical neurons thought to be selectively affected in dementia with Lewy bodies (DLB) are those containing nonphosphorylated 200-kDa neurofilament (NF) protein. As these neurons are largely spared in Alzheimer's disease (AD), DLB and AD may impact on different cortical neuronal populations. The present study quantifies the NF-containing neurons in frontal and temporal cortex of 8 AD, 8 DLB, and 8 control cases. Formalin-fixed paraffin-embedded tissue was immunohistochemically stained with antibodies against nonphosphorylated and phosphorylated NF. Immunoreactive neurons were quantified by areal fraction analysis and corrected for cortical volume. As expected, nonphosphorylated and phosphorylated NF accumulated in the pathological hallmarks of AD and DLB. However, rather than a decrease in NF-containing neurons, a doubling of this population was observed in DLB, compared with AD and controls. This increased number of cortical NF-containing neurons reveal novel widespread cortical changes, beyond those explained by Lewy body formation, that are specific for DLB.