# Shorter Telomere Length in Individuals with Neurocognitive Disorder and APOE ε4 Genotype

## TL;DR

This study finds that shorter telomeres and lower education are linked to higher risk of cognitive impairment, especially in APOE ε4 carriers.

## Contribution

The study reveals a novel interaction between APOE ε4 genotype, telomere length, and education in cognitive impairment risk.

## Key findings

- Shorter telomere length is significantly associated with increased cognitive impairment risk.
- APOE ε4 carriers with cognitive impairment tend to have shorter telomeres than those without.
- Lower educational levels strongly correlate with higher cognitive impairment risk.

## Abstract

Neurocognitive disorders (NCD) are neurodegenerative diseases characterized by decline or loss of cognitive functions. Aging and the APOE genotype have been identified as major risk factors. Telomere length (TL) has been proposed as a biomarker of aging, with shorter TL associated with cognitive decline. This study investigated the relationship between TL and the APOE genotype in individuals with cognitive impairments (CIs). A total of 170 participants aged >55 years were included. Cognitive function was assessed using the MMSE and MoCA tests. Relative telomere quantification and APOE genotype were determined by real-time PCR. A significant association was observed between shorter TL and an increased risk of CI (p < 0.001). Although APOE ε4 is a known genetic risk factor, its association with CI was less clear in this study population, as a considerable proportion of ε4 carriers did not present cognitive impairment (p < 0.05). However, ε4 carriers with CI tended to have shorter TL than those with non-cognitive impairment (NCI-SMC). Furthermore, fewer years of education were strongly correlated with higher CI risk (p < 0.0001). Overall, individuals with both shorter telomeres and lower educational levels exhibited the highest risk of CI. APOE ε4 may contribute to telomere shortening.