Higher Prevalence of TDP-43 Proteinopathy in Cognitively Normal Asians: A Clinicopathological Study on a Multiethnic Sample

Transactive response DNA binding protein 43 (TDP-43) proteinopathy is the major hallmark of frontotemporal lobar degeneration and amyotrophic lateral sclerosis. It is also present in a subset of Alzheimer's disease cases. Recently, few reports showed TDP-43 changes in cognitively normal elderly. In Caucasians, TDP-43 proteinopathy independently correlate with cognitive decline. However, it is challenging to establish direct links between cognitive and/or neuropsychiatric symptoms and protein inclusions in neurodegenerative diseases because individual cognitive reserves modify the threshold for clinical disease expression. Cognitive reserve is influenced by demographic, environmental and genetic factors. We investigated the relationships between demographic, clinical and neuropathological variables and TDP-43 proteinopathy in a large multiethnic sample of cognitively normal elderly. TDP-43 proteinopathy was identified in 10.5%, independently associated with older age (P=0.03) and Asian ethnicity (P=0.002). Asians showed a higher prevalence of TDP-43 proteinopathy than Caucasians, even after adjustment for sex, age, Braak stage and schooling (odds ratio=3.50, confidence interval 1.41-8.69, P=0.007). These findings suggested that Asian older adults may be protected from the clinical manifestation of brain TDP-43 proteinopathy. Future studies are needed to identify possible race-related protective factors against clinical expression of TDP-43 proteinopathies.