Leukocyte Telomere Length Is Unrelated to Cognitive Performance Among Non-Demented and Demented Persons: An Examination of Long Life Family Study Participants

Abstract

Objective: Leukocyte telomere length (LTL) is a widely hypothesized biomarker of biological aging. Persons with shorter LTL may have a greater likelihood of developing dementia. We investigate whether LTL is associated with cognitive function, differently for individuals without cognitive impairment versus individuals with dementia or incipient dementia. Method: Enrolled subjects belong to the Long Life Family Study (LLFS), a multi-generational cohort study, where enrollment was predicated upon exceptional family longevity. Included subjects had valid cognitive and telomere data at baseline. Exclusion criteria were age ≤ 60 years, outlying LTL, and missing sociodemographic/clinical information. Analyses were performed using linear regression with generalized estimating equations, adjusting for sex, age, education, country, generation, and lymphocyte percentage. Results: Older age and male gender were associated with shorter LTL, and LTL was significantly longer in family members than spouse controls (p < 0.005). LTL was not associated with working or episodic memory, semantic processing, and information processing speed for 1613 cognitively unimpaired individuals as well as 597 individuals with dementia or incipient dementia (p < 0.005), who scored significantly lower on all cognitive domains (p < 0.005). Conclusions: Within this unique LLFS cohort, a group of families assembled on the basis of exceptional survival, LTL is unrelated to cognitive ability for individuals with and without cognitive impairment. LTL does not change in the context of degenerative disease for these individuals who are biologically younger than the general population.

Meta-analysis of the Connection Between Alzheimer Disease and Telomeres

“…The flow chart of the selection process was exhibited in Figure 1. In total, 25 articles met our inclusion criteria 3–19,22–29. Among these studies, 22 articles were on the study of TL, 1 article was on the study of telomerase activity, and the remaining 2 articles focused on TL and telomerase activity.…”

“…In total, 25 articles met our inclusion criteria. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][22][23][24][25][26][27][28][29] Among these studies, 22 articles were on the study of TL, 1 article was on the study of telomerase activity, and the remaining 2 articles focused on TL and telomerase activity. Besides, Thomas et al 19 studied the TL of white blood cells, buccal cells, and brain tissue in AD patients and the matched controls, and the AD patients were divided into young and old AD groups, respectively.…”

“…The stability of the telomere-telomerase system is closely related to AD. Studies have shown that telomere shortening has a close relationship with the increasing risk of AD, [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] but some studies hold the opposite view. 18 Studies have found that the maintenance of telomeres in AD patients is significantly different among different sampled tissues.…”

Is Telomere Length Shortening a Risk Factor for Neurodegenerative Disorders?

“…One study has reported no correlation between telomere length and cognitive performance among non-demented and demented people in long-life family study participants. 36 It has also been reported that telomere length is not predictive of dementia or MCI conversion in the oldest old. 37 One study has shown that both longer telomere length and shorter telomere length are associated with an increased risk of AD in the Rotterdam study.…”

The associations of socioeconomic status with incident dementia and Alzheimer’s disease are modified by leucocyte telomere length: a population-based cohort study

“…Nonetheless, one large prospective study comprising n = 1,961 Dutch participants reported an U-shaped association, with higher risks of Alzheimer’s disease in the lowest and highest tertiles of TL relative to the middle tertile 28 . While, another cross sectional study comprising n = 2,210 participants demonstrating exceptional longevity from USA and Denmark reported null associations between leucocyte TL and cognitive performance in both cognitively unimpaired and demented sub-groups 29 .…”