Changes in glucose metabolism due to aging and gender-related differences in the healthy human brain

Brain Structural Variability due to Aging and Gender in Cognitively Healthy Elders: Results from the São Paulo Ageing and Health Study

“…27 rGM metabolic and volumetric decline in the hippocampus/parahippocampal gyrus is considered an important biomarker for the early detection of Alzheimer disease, 28,29 and it has been suggested that the presence of volumetric decline in limbic structures should be considered a sign of pathologic brain aging. 28,29 However, recently published structural and functional imaging studies reported findings that are consistent with the results described herein, 2,27,30 and the paucity of previous morphometric MR imaging studies specifically evaluating cognitively healthy subjects in the age range assessed in our study 7,27 may have reinforced the concept of medial temporal atrophy as necessarily denoting pathologic changes of the aging brain. Findings of rGM volume and/or metabolic preservation in the hippocampal region in healthy aging are mainly found in studies evaluating samples spanning a large age range.…”

Age-Related Metabolic Profiles in Cognitively Healthy Elders: Results from a Voxel-Based [18F]Fluorodeoxyglucose–Positron-Emission Tomography Study with Partial Volume Effects Correction: Fig 1.

“…Regarding the anterior cingulate, in which age-related metabolic reduction has been shown in younger samples, 7,8 the lack of negative correlations in our analyses might reflect a specific pattern of the elderly population. According to the study of Fujimoto et al, 7 the effect size of this correlation in normal aging during adult life is particularly high. Therefore, a small number of subjects would be necessary to accurately detect it, and it is unlikely that our lack of results is secondary to a type II error.…”

“…[2][3][4][5][6] Nevertheless, more recent studies have reported decrements in glucose metabolism in several prefrontal, parietal, and temporal areas during the life span, with relative preservation of limbic structures, the cerebellum, and occipital cortex. [7][8][9][10][11][12] One possible explanation for the difference between newer and older reports of aging-associated brain functional variability is the improvement in PET scanners 13 and the development of automated methods of analysis, 14 which together have clearly increased the power to detect CMRglc changes associated with normal aging. However, it has been suggested that such aging-related CMRglc variability in cognitively healthy individuals could be due to PVE, which cause an apparent metabolic reduction in areas with steep GM atrophy and artificial metabolic preservation in areas with less pronounced GM reduction.…”

Cardiovascular risk in cognitively preserved elderlies is associated with glucose hypometabolism in the posterior cingulate cortex and precuneus regardless of brain atrophy and apolipoprotein gene variations

“…However, because we co-varied all our analyses for between-group gender differences, our results are unlikely to simply reflect such gender imbalance across the groups. Moreover, previous literature findings indicate that gender differences influence glucose metabolic patterns most notably in frontal lobe regions, with lower metabolic rate in males relative to females (Baxter et al 1987;Yoshii et al 1988;Andreason et al 1994;Fujimoto et al 2008). This would potentially lead to reduced prefrontal metabolism in the high-risk group compared to the low-risk group in our study, rather than a sparing of the frontal cortex in high-risk individuals as we found.…”

“…This is in consistence with previous epidemiological investigations of vascular risk in elderly populations (Elias et al 1997;Ishii et al 2009). Such demographic imbalance has to be highlighted, given the evidence that gender differences clearly influence CMRgl distribution in healthy elderly subjects (Fujimoto et al 2008;Curiati et al 2011). However, because we co-varied all our analyses for between-group gender differences, our results are unlikely to simply reflect such gender imbalance across the groups.…”