Telomeres linked to higher dementia risk

The results of a lengthy, large-scale study, which were published online in the journal General Psychiatry, propose that shorter telomeres at the tips of chromosomes in white blood cells might indicate an elevated risk of dementia. According to the researchers, this shortening of telomeres is linked to reduced overall brain volume, including white matter, which plays a crucial role in information processing. It could potentially serve as a predictor of future brain health.

In this study, the researchers investigated the relationship between the length of telomeres in white blood cells and the risk of dementia, including Alzheimer’s disease and vascular dementia, as well as total and specific brain volumes. To conduct their research, they utilised data from the UK Biobank, a comprehensive biomedical database containing detailed genetic and health information from approximately half a million individuals in the UK who were enrolled between 2006 and 2010.

The length of telomeres in white blood cells was assessed by analysing blood samples collected during enrolment. These data were available for 439,961 individuals, aged 37 to 73 at the time (with an average age of 56). Over an average monitoring period of nearly 12 years, 1551 participants (0.4 percent) were diagnosed with Alzheimer’s disease, 767 (0.2 percent) with vascular dementia, and 5820 (1.3 percent) with other types of dementia.

Upon analysing the data, the researchers found a significant connection between the length of telomeres in white blood cells and the subsequent risk of dementia. After adjusting for gender and age, individuals with the shortest telomeres were 14 percent more likely to be diagnosed with dementia and 28 percent more likely to be diagnosed with Alzheimer’s disease compared to those with the longest telomeres. While the risk of vascular dementia also increased (by 18 percent), this finding did not reach statistical significance.

Additionally, brain structure was examined through full-body MRI scans in 38,740 participants in 2014. The results revealed a linear relationship between shorter telomeres in white blood cells and smaller total brain volume, white matter, as well as specific brain structures such as the hippocampus (associated with learning and memory), the thalamus (responsible for sensory processing), and the nucleus accumbens.

It’s important to note that this study is observational and cannot establish causation. The researchers acknowledge several limitations, including the fact that telomere length was measured only once, making it impossible to determine whether changes over time might have influenced dementia risk. Additionally, telomere length was measured solely in white blood cells, and measuring it in glial cells in the central nervous system could potentially provide even more valuable insights, although this data was not available from the UK Biobank. Lastly, dementia diagnoses relied on electronic health records, which might not have been up-to-date and may have missed milder forms of the condition.