The general age of the world population is increasing as a result of advances in medical technology and reduced birth rates in lots of countries. This has led to a major increase within the variety of older adults who lose partial or complete independence as a result of dementia and, consequently, require look after the remainder of their lives.

A recent paper in General Psychiatry explores the worth of leukocyte chromosomal changes called telomere shortening for predicting dementia in aging populations.

Study: Leucocyte telomere length, brain volume and risk of dementia: a prospective cohort study. Image Credit: peterschreiber.media / Shutterstock.com

Introduction

Leukocyte telomere length (LTL) could also be related to brain health, thus offering an approach to predict dementia before its clinical onset; nevertheless, evidence supporting this hypothesis is lacking.

Chronological age stays the first predictor of dementia risk. Leukocyte telomeres are the protein-bound ends of each chromosome that prevent the lack of DNA. Telomeres shorten with every cell division, thus causing older people to have significantly shorter telomeres.

Each chronological and biological age will be assessed using telomere length, which could help predict the chance of age-related diseases like dementia. Nevertheless, large-scale population-level screening for diseases using LTL is inefficient and never cost-effective.

Previous studies have suggested that decreasing LTL is related to age-related diseases, including dementia; nevertheless, the evidence is inconsistent. Brain shrinkage on magnetic resonance imaging (MRI) has been used to diagnose dementia and mild cognitive impairment; nevertheless, lots of these studies examined specific brain regions or included small sample sizes.

The UK Biobank provides prospective data from a big cohort of over 500,000 patients, lots of whom have contributed to LTL data using quantitative polymerase chain response (PCR) testing.

The present study used LTL data from over 430,000 individuals who entered the study between 2006 and 2010 and were monitored until 2020. The incidence of dementia, including Alzheimer’s disease (AD) and vascular dementia (VD), was determined using electronic health records (EHR). Brain volume was also assessed in almost 39,000 individuals using magnetic resonance imaging (MRI).

This study aimed to discover any association between these measures. Several confounding aspects were considered within the evaluation, including social and demographic attributes and chronic diseases, in addition to lifestyle characteristics.

What did the study show?

The median follow-up period was roughly 12 years, during which 1.3% of the population, or 5,820 people, developed dementia. AD and VD were detected in 0.4% and 0.2% of the study cohort, respectively.

LTL was significantly related to the chance of overall dementia, particularly AD, whereas VD was not found to have this association. After adjusting for multiple confounding aspects, including age and sex, the bottom LTL tertile was 14% for an increased risk of dementia as in comparison with those in the very best tertile. For AD, the chance was increased by 28%.

The association remained robust to self-reported cardiovascular or depressive disease or cancer in the beginning of the study or after excluding cases that developed through the first two years of the study. Nevertheless, the results were stronger at younger ages and in people with no family history of dementia.

Shortening of the leukocyte telomere was related to shrinking of the brain, with total brain volume and various specific parts of the brain related to smaller values as in comparison with those in individuals with longer telomeres. The shrinkage was observed for total white matter, hippocampus, thalamus, and nucleus accumbens.

There was no difference on this association after adjusting for sex differences or the presence of apolipoprotein E (APOE) ε4, which is a risk factor for dementia. The associations remained consistent after excluding those that already had dementia in the beginning of the study.

The inclusion of LTL right into a model to predict dementia risk barely improved the discrimination of the model. When multiple brain volumes were considered within the model, its predictive value increased to about 85% of the world under the curve.

What are the implications?

Shorter LTL is related to total and regional brain structure and a better risk of incident dementia and AD, implying the potential of telomere length as a predictive biomarker of brain health.”

LTL is basically inherited; subsequently, shorter LTL may help provide a basis for lifestyle counseling, because it indicates poor neuropsychological condition. Glial cell telomere measurements might need been higher for the aim but were unavailable in any large-scale study.