Resilience of Neural Cellularity to the Influence of Low Educational Level.

BACKGROUND: Education is believed to contribute positively to brain structure and function, as well as to cognitive reserve. One of the brain regions most impacted by education is the medial temporal lobe (MTL), a region that houses the hippocampus, which has an important role in learning processes and in consolidation of memories, and is also known to undergo neurogenesis in adulthood. We aimed to investigate the influence of education on the absolute cell numbers of the MTL (comprised by the hippocampal formation, amygdala, and parahippocampal gyrus) of men without cognitive impairment. METHODS: The Isotropic Fractionator technique was used to allow the anisotropic brain tissue to be transformed into an isotropic suspension of nuclei, and therefore assess the absolute cell composition of the MTL. We dissected twenty-six brains from men aged 47 to 64 years, with either low or high education. RESULTS: A significant difference between groups was observed in brain mass, but not in MTL mass. No significant difference was found between groups in the number of total cells, number of neurons, and number of non-neuronal cells. Regression analysis showed that the total number of cells, number of neurons, and number of non-neuronal cells in MTL were not affected by education. CONCLUSIONS: The results indicate a resilience of the absolute cellular composition of the MTL of typical men to low schooling, suggesting that the cellularity of brain regions is not affected by formal education.

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.

Chronic Traumatic Encephalopathy Presenting as Alzheimer's Disease in a Retired Soccer Player.

The relationship between soccer and chronic traumatic encephalopathy (CTE) is not well established. We report clinicopathological correlations in an 83-year-old retired center-back soccer player, with no history of concussion, manifesting typical Alzheimer-type dementia. Examination revealed mixed pathology including widespread CTE, moderate Alzheimer's disease, hippocampal sclerosis, and TDP-43 proteinopathy. This case adds to a few CTE cases described in soccer players. Furthermore, it corroborates that CTE may present clinically as typical Alzheimer-type dementia. Further studies investigating the extent to which soccer is a risk for CTE are needed.