TDP-43 pathology in Alzheimer's disease, dementia with Lewy bodies and ageing.

Intracellular inclusions consisting of TAR DNA binding protein-43 (TDP-43 pathology) are present in up to 57% of Alzheimer's disease (AD) cases and follow a distinct topographical pattern of progression described in the TDP-43 in AD staging scheme. This scheme has not been applied to the assessment of TDP-43 pathology in dementia with Lewy bodies (DLB) and aged controls. We investigated TDP-43 pathology prevalence and severity in AD, DLB, mixed AD/DLB (Mx AD/DLB) and aged controls. One hundred and nineteen human post-mortem brains were included, neuropathologically diagnosed as AD: 46, DLB: 15, Mx AD/DLB: 19 and aged controls: 39. Paraffin sections inclusive of the amygdala, hippocampus, striatum and neocortex were immunohistochemically stained with antibodies against phosphorylated TDP-43 and staged according to the TDP-43 in AD staging scheme. TDP-43 pathology was present in all groups: AD: 73.9%, DLB: 33.3%, Mx AD/DLB: 52.6% and controls: 17.9%. Prevalence of TDP-43 pathology was significantly higher in AD and Mx AD/DLB compared to controls. In controls, higher age at death was associated with prevalence of TDP-43 pathology and higher TDP-43 in AD stage, suggesting that this type of TDP-43 pathology may partly be an age-associated phenomenon. Significantly higher prevalence of TDP-43 pathology in the AD group indicates that AD pathology possibly triggers and aggravates TDP-43 pathology. The validity of the TDP-43 in AD staging scheme is not limited to AD and should be applied to assess TDP-43 pathology in post mortem brains of aged individuals to further elucidate the role of TDP-43 pathology in age associated neurodegeneration.