Increased Efficiency of Mitochondrial Coupling With a Reduction in Other Mitochondrial Respiratory Parameters in Peripheral Blood Mononuclear Cells Is Observed in Older Adults.

Mitochondrial dysfunction is a factor potentially contributing to the Aging process. However, evidence surrounding changes in mitochondrial function and aging is still limited; therefore, this study aimed to investigate further the association between them. Possible confounding factors were included in the statistical analysis to explore the possibility of any independent associations. One thousand seven hundred and sixty-nine participants (619 middle-aged adults [age < 65] and 1,150 older adults [age ≥ 65]) from the Electricity Generating Authority of Thailand were enrolled in the study. The clinical characteristics and medical history were collected. Peripheral blood mononuclear cells (PBMCs) were isolated from venous blood and used for analysis of mitochondrial function. Several parameters pertinent to mitochondrial respiration including non-mitochondrial respiration, basal respiration, maximal respiration, proton leak, and spare respiratory capacity were found to be two to three times lower in the mitochondria isolated from the cells of older adults. Interestingly, the mitochondrial ATP production was only slightly reduced, and the percentage of coupling efficiency of PBMC mitochondria was significantly higher in the older adult group. The mitochondrial mass and oxidative stress were significantly reduced in older adult participants; however, the ratio of oxidative stress to mass was significantly increased. The association of these parameters with age was still shown to be the same from the outcome of the multivariate analyses. The mitochondrial functions and mitochondrial mass in PBMCs were shown to decline in association with age. However, the upregulation of mitochondrial oxidative stress production and mitochondrial coupling efficiency might indicate a compensatory response in mitochondria during aging.

Cognitive impairment is associated with mitochondrial dysfunction in peripheral blood mononuclear cells of elderly population.

Cognitive impairment is commonly found in the elderly population. Evidence suggests that mitochondrial function in lymphocytes are potential biomarkers in the progression of neurodegeneration, as peripheral mitochondrial function is associated with mild cognitive impairment (MCI) in the elderly population. Therefore, we hypothesize that impaired mitochondrial ATP production and oxidative stress in peripheral blood mononuclear cells (PBMCs) are associated with cognitive impairment in the elderly population. Data were collected from 897 participants from the EGAT (The Electricity Generating Authority of Thailand) cohort. The participants were classified to be in the normal cognition group (n = 428) or mild cognitive impairment group (n = 469), according to their MoCA score. The association of mitochondrial function and cognitive status was analyzed by binary logistic regression analysis. MCI participants had higher age, systolic blood pressure, waist/hip ratio, and lower plasma high- and low-density lipoprotein cholesterol levels, when compared to the normal cognition group. In addition, estimated glomerular filtration rate were lower in the MCI group than those in the normal cognition group. Collectively, MCI is associated with mitochondrial dysfunction in PBMCs as indicated by decreasing mitochondrial ATP production, increasing proton leak, and oxidative stress, in the elderly population, independently of the possible confounding factors in this study.