Cognitive deficit, and neuropathological correlates, in the oldest-old

The correlation between neuropathology levels and cognitive performance in centenarians

INTRODUCTION

Neuropathological substrates associated with neurodegeneration occur in brains of the oldest old. How does this affect cognitive performance?

METHODS

The 100-plus Study is an ongoing longitudinal cohort study of centenarians who self-report to be cognitively healthy; post mortem brain donation is optional. In 85 centenarian brains, we explored the correlations between the levels of 11 neuropathological substrates with ante mortem performance on 12 neuropsychological tests.

RESULTS

Levels of neuropathological substrates varied: we observed levels up to Thal-amyloid beta phase 5, Braak-neurofibrillary tangle (NFT) stage V, Consortium to Establish a Registry for Alzheimer's Disease (CERAD)-neuritic plaque score 3, Thal-cerebral amyloid angiopathy stage 3, Tar-DNA binding protein 43 (TDP-43) stage 3, hippocampal sclerosis stage 1, Braak-Lewy bodies stage 6, atherosclerosis stage 3, cerebral infarcts stage 1, and cerebral atrophy stage 2. Granulovacuolar degeneration occurred in all centenarians. Some high performers had the highest neuropathology scores.

DISCUSSION

Only Braak-NFT stage and limbic-predominant age-related TDP-43 encephalopathy (LATE) pathology associated significantly with performance across multiple cognitive domains. Of all cognitive tests, the clock-drawing test was particularly sensitive to levels of multiple neuropathologies.

The interplay between micro RNAs and genetic liability to Alzheimer's Disease on memory trajectories in the general population

Deficits in cognitive function and memory are common early symptoms of neurodegenerative disorders, such as Alzheimer's Disease (AD). Several studies have discussed micro RNAs (miRNAs) as potential epigenetic early detection biomarkers. In a longitudinal general population sample (n = 548) from the Study of Health in Pomerania, we analyzed the associations between 167 baseline miRNA levels and changes in verbal memory scores with a mean follow-up time of 7.4 years. We additionally assessed the impact of an individual's genetic liability for AD on verbal memory scores in n = 2,334 subjects and a possible interactions between epigenetic and genetic markers. Results revealed two miRNAs associated with changes in immediate verbal memory over time. In interaction analyses between miRNAs and a polygenic risk score for AD, five miRNAs showed a significant interaction effect on changes in verbal memory. All of these miRNAs have previously been identified in the context of AD, neurodegeneration or cognition. Our study provides candidate miRNAs for a decline in verbal memory as an early symptom of neurodegeneration and AD. Further experimental studies are needed to verify the diagnostic value of these miRNA markers in the prodromal stage of AD.

Normative data for test of learning and memory in an ecuadorian adult population

OBJECTIVE

The objective of this study was to develop norms for two neuropsychological tests of learning and memory in an Ecuadorian adult population.

METHOD

322 healthy individuals, ages between 18 and 84, were enrolled in the Metropolitan District of Quito. Participants were administered a comprehensive neuropsychological evaluation that included tests of learning and memory (Rey-Osterrieth Complex Figure Test [ROCF] and Hopkins Verbal Learning Test-Revised [HVLT-R]). Backward stepwise multiple linear regression analyses were used to examine the influence of demographic variables age, education, and gender on test performance. Normative data were developed adjusting for demographic variables found to be significant in the final regression models.

RESULTS

The final multiple linear models revealed performance on tests of learning and memory worsened with age and improved as a function of education. A user-friendly Excel-based calculator is presented to calculate the z score and percentile automatically based on raw score and sociodemographic information.

CONCLUSION

This is the first study that presents normative data for tests of learning and memory for an adult population in Ecuador. It is expected that these norms will help to improve the clinical practice of neuropsychology in Ecuador by limiting erroneous raw score interpretation and incrementing diagnostic accuracy.