Age-related total gray matter and white matter changes in normal adult brain. Part I: Volumetric MR imaging analysis
ABSTRACT A technique of segmenting total gray matter (GM) and total white matter (WM) in human brain is now available. We investigated the effects of age and sex on total fractional GM (%GM) and total fractional WM (%WM) volumes by using volumetric MR imaging in healthy adults.
Fifty-four healthy volunteers (22 men, 32 women) aged 20-86 years underwent dual-echo fast spin-echo MR imaging. Total GM, total WM, and intracranial space volumes were segmented by using MR image-based computerized semiautomated software. Volumes were normalized as a percentage of intracranial volume (%GM and %WM) to adjust for variations in head size. Age and sex effects were then assessed.
Both %GM and %WM in the intracranial space were significantly less in older subjects (> or =50 years) than in younger subjects (<50 years) (P <.0001 and P =.02, respectively). Consistently, %GM decreased linearly with age, beginning in the youngest subjects. %WM decreased in a quadratic fashion, with a greater rate beginning only in adult midlife. Although larger GM volumes were observed in men before adjustments for cranium size, no significant differences in %GM or %WM were observed between the sexes.
GM volume loss appears to be a constant, linear function of age throughout adult life, whereas WM volume loss seems to be delayed until middle adult life. Both appear to be independent of sex. Quantitative analysis of %GM and %WM volumes can improve our understanding of brain atrophy due to normal aging; this knowledge may be valuable in distinguishing atrophy of disease patterns from characteristics of the normal aging process.
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- "We specifically tested whether increased levels of depression would correlate with decreased GMV. Age and whole brain gray matter volume (WBGM) were included as covariates to control for their potentially confounding effects on regional gray matter (Ge et al., 2002). "
ABSTRACT: Major depressive disorder is associated with lower medial prefrontal cortex volumes. The role that gender might play in moderating this relationship and what particular medial prefrontal cortex subregion(s) might be implicated is unclear. Magnetic resonance imaging was used to assess dorsal, ventral, and anterior cingulate regions of the medial prefrontal cortex in a normative sample of male and female adults. The Depression, Anxiety, and Stress Scale (DASS) was used to measure these three variables. Voxel-based morphometry was used to test for correlations between medial prefrontal gray matter volume and depressive traits. The dorsal medial frontal cortex was correlated with greater levels of depression, but not anxiety and stress. Gender moderates this effect: in males greater levels of depression were associated with lower dorsal medial prefrontal volumes, but in females no relationship was observed. The results indicate that even within a non-clinical sample, male participants with higher levels of depressive traits tend to have lower levels of gray matter volume in the dorsal medial prefrontal cortex. Our finding is consistent with low dorsal medial prefrontal volume contributing to the development of depression in males. Future longitudinal work is needed to substantiate this possibility. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.Psychiatry Research Neuroimaging 06/2015; DOI:10.1016/j.pscychresns.2015.06.005 · 2.83 Impact Factor
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- "By contrast, white matter aging follows a quadratic pattern of change that peaks around the fourth decade and declines thereafter ( Ge et al., 2002 ; Sowell et al., 2003 ; Giorgio et al., 2010 ). The inverse relationship between gray matter and white matter in early adulthood likely contributes to the relative stability of total brain volume (defined strictly by gray and white matter tissue) until middle age and also suggests that decline in total brain volume is heavily dependent on the transition from white matter maturation to degeneration in middle adulthood ( Ge et al., 2002 ). This idea is consistent with evidence that white matter, not gray matter, partially mediates the relationship between normal aging and increased intraindividual variability on various cognitive tasks ( Moy et al., 2011 ). "
ABSTRACT: Abstract Normal aging involves a gradual breakdown of physiological processes that leads to a decline in cognitive functions and brain integrity, yet the onset and progression of decline are variable among older individuals. While many biological changes may contribute to this degree of variability, oxidative stress is a key mechanism of the aging process that can cause direct damage to cellular architecture within the brain. Oligodendrocytes are at a high risk for oxidative damage due to their role in myelin maintenance and production and limited repair mechanisms, suggesting that white matter may be particularly vulnerable to oxidative activity. Antioxidant defense enzymes within the brain, such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione-S-transferase (GST), are crucial for breaking down the harmful end products of oxidative phosphorylation. Previous studies have revealed that allele variations of polymorphisms that encode these antioxidants are associated with abnormalities in SOD, CAT, GPx, and GST activity in the central nervous system. This review will focus on the role of oxidative stress in the aging brain and the impact of decreased antioxidant defense on brain integrity and cognitive function. Directions for future research investigations of antioxidant defense genes will also be discussed.Reviews in the neurosciences 08/2014; 25(6). DOI:10.1515/revneuro-2014-0046 · 3.31 Impact Factor
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- "In typically developing children, post-natal development of white matter is more protracted than gray matter, and continues during childhood and adolescence and into midlife ( Riddle et al., 2010 ; Welker and Patton, 2012 ). Specifically, during childhood and adolescence, there are significant age-related increases in white matter volume, with peak volumes occurring between 12 and 14 years in the frontal and temporal lobes to around 20–24 years for the parietal lobes ( Giedd et al., 1999 ; Ge et al., 2002 ; Gogtay et al., 2004 ; Tamnes et al., 2010 ; Raznahan et al., 2011 ; Tanaka et al., 2012 ). Increases in white matter volume are attributed to increases in myelination and potentially to changes in the size, density, and number of white matter fibers over time ( Paus et al., 1999 ; Welker and Patton, 2012 ). "
ABSTRACT: Prenatal alcohol exposure can cause a wide range of deficits in executive function that persist throughout life, but little is known about how changes in brain structure relate to cognition in affected individuals. In the current study, we predicted that the rate of white matter volumetric development would be atypical in children with fetal alcohol spectrum disorders (FASD) when compared to typically developing children, and that the rate of change in cognitive function would relate to differential white matter development between groups. Data were available for 103 subjects [49 with FASD, 54 controls, age range 6-17, mean age = 11.83] with 153 total observations. Groups were age-matched. Participants underwent structural magnetic resonance imaging (MRI) and an executive function (EF) battery. Using white matter volumes measured bilaterally for frontal and parietal regions and the corpus callosum, change was predicted by modeling the effects of age, intracranial volume, sex, and interactions with exposure status and EF measures. While both groups showed regional increases in white matter volumes and improvement in cognitive performance over time, there were significant effects of exposure status on age-related relationships between white matter increases and EF measures. Specifically, individuals with FASD consistently showed a positive relationship between improved cognitive function and increased white matter volume over time, while no such relationships were seen in controls. These novel results relating improved cognitive function with increased white matter volume in FASD suggest that better cognitive outcomes could be possible for FASD subjects through interventions that enhance white matter plasticity.06/2014; 5:19-27. DOI:10.1016/j.nicl.2014.05.010