الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Ageing is an inevitable multifactorial process. Many theories are trying to explain it, such as the ROS’s effect on mitochondria, the accumulation of undegradable metabolism by-products, the impairment of regulatory pathways, the biological clocks and metabolism rates, and the telomere shortening. Although cell senescence does not mean organismal ageing, TS has been observed in both conditions and in many ARDs.(56, 57)
Our study aimed at studying the correlations between telomere lengths, vitamin D levels, and cognitive functions in a random sample of older people. We included 100 older people aged 65 or more who do not have diabetes mellitus, malignancy, autoimmune diseases, or renal diseases and do not take vitamin D supplementation. Informed consent was taken from every participant. Thorough history taking and complete clinical examination were done. Cognitive functions assessment was done using the MoCA score. Basic laboratory tests and measurement of vitamin D level were performed. Assessment of telomere length for each sample was performed using real-time PCR and calculating the T/S ratio. Correlations were done among telomere length, 25-hydroxyvitamin D levels, cognitive functions, and basic laboratory tests, including hs-CRP, to detect any significant correlations between them.
Our study found a statistically significant negative correlation between the T/S ratio and WBC count or neutrophil count (table 9). Using univariate regression analysis, we have found significant positive correlations between Vit D and each of the following: educational level, haemoglobin level, albumin level, eGFR, or MOCA and significant negative correlations between Vit D and each of the following: female sex and hs-CRP. However, after multivariate regression analysis, there were only a significant positive correlation between Vit D and haemoglobin level, a significant positive correlation between Vit D and MoCA, and a significant negative correlation between Vit D and being a female (table 10). Using univariate regression analysis, we have found significant positive correlations between MoCA and each of the following: educational level, haemoglobin level, eGDR, and Vit D and significant negative correlations between MoCA and each of the following: WBCs count, neutrophils count, or hs-CRP. However, after multivariate regression analysis, there were only a significant positive correlation between MoCA and educational level and a significant negative correlation between MoCA and neutrophils count. There was a positive, however, statistically not significant correlation between the T/S ratio and vitamin D. Also, there was a negative but statistically not significant correlation between the T/S ratio and MoCA (table 11).