Association between dementia risk, size of white blood cell telomeres

Shorter telomeres on the ends of white blood cell chromosomes were discovered to be associated with an increased risk of dementia.

The findings were published in the journal General Psychiatry online.

According to the researchers, they are associated with reduced total and white matter c, which aids in information processing and may be a predictor of future brain health.

A telomere, which looks like a shoelace cap, is intended to keep chromosomes from fraying or unravelling during replication.

They went on to evaluate potential correlations between leucocyte telomere length and dementia risk, including Alzheimer's disease and vascular dementia, as well as total and regional brain volumes, using data from the UK Biobank.

The UK Biobank is a massive biological database that contains detailed genetic and health information for around 500,000 persons in the United Kingdom who were registered between 2006 and 2010.

The length of leucocyte telomeres was determined by analysing blood samples collected at the time of enrollment. At the time, these data were available for 439, 961 people ranging in age from 37 to 73 (average age 56).

The data analysis found a substantial link between leucocyte telomere length and the risk of dementia.

Participants with the shortest leucocyte telomeres were 14 per cent more likely to be diagnosed with dementia and 28 per cent more likely to be diagnosed with Alzheimer's disease after controlling for gender and age.

Although not statistically significant, the risk of vascular dementia increased (18 per cent).

In 2014, 38,740 people had their brain anatomy visualised using MRI complete body scans. This demonstrated a linear relationship between shorter leucocyte telomeres and decreased overall brain volume, white matter, and brain regions such as the hippocampus (engaged in learning and memory), the thalamus (sensory processing centre), and the nucleus accumbens (the 'pleasure centre').

Because this is an observational study, it cannot determine the cause. The researchers also point out several limitations: Because telomere length was only assessed once, it was unable to determine whether changes over time increased dementia risk. Furthermore, telomere length was only measured in leucocytes.

They believe that measuring telomere length in glial cells (non-neuronal cells in the central nervous system) would have been more revealing, but this information was not available from the UK Biobank.

Furthermore, dementia diagnoses were collected solely from electronic health records, which may or may not have been up to date and may not have included milder types.

Nevertheless, the researchers conclude, “We found that leucocyte telomere length acts as an aging biomarker associated with the risk of dementia. Furthermore, we also observed linear associations of leucocyte telomere length with total and regional brain structure.

“These findings highlight telomere length as a potential biomarker of brain health.”