scholarly journals The causal structure of age-dependent limbic decline: fornix white matter glia damage causes hippocampal grey matter damage, not vice versa

2018 ◽  
Author(s):  
Claudia Metzler-Baddeley ◽  
Jilu P. Mole ◽  
Rebecca Sims ◽  
Fabrizio Fasano ◽  
John Evans ◽  
...  
Keyword(s):  
White Matter ◽  
Gray Matter ◽  
Mediation Analysis ◽  
Late Onset ◽  
Causal Structure ◽  
Tissue Loss ◽  
Hippocampal Damage ◽  
White Matter Damage ◽  
Tissue Properties ◽  
Age Related

AbstractAging leads to gray and white matter decline but their causation remains unclear. We explored two broad classes of models of age and dementia risk related brain changes. The first class of models emphasises the importance of gray matter: age and risk-related processes cause neurodegeneration and this causes damage in associated white matter tracts. The second class of models reverses the direction of causation: aging and risk factors cause white matter damage and this leads to gray matter damage. We compared these models with linear mediation analysis and quantitative multi-modal MRI indices (from diffusion, quantitative magnetization transfer and relaxometry imaging) of tissue properties in two limbic structures implicated in age-related memory decline: the hippocampus and the fornix in 166 asymptomatic individuals (aged 38 - 71 years). Aging was associated with apparent glia but not axon density damage in the fornix. Mediation analysis unambiguously supported white matter damage causing gray matter decline; controlling for fornix glia damage, the correlation between age and hippocampal damage disappears, but not vice versa. Fornix and hippocampal tissue loss were both associated with reductions in episodic memory performance. The implications of these findings for neuroglia and neurodegenerative models of aging and late onset dementia are discussed.

scholarly journals Brain Substrates of Time-Based Prospective Memory Decline in Aging: A Voxel-Based Morphometry and Diffusion Tensor Imaging Study

2020 ◽  
Vol 31 (1) ◽  
pp. 396-409
Author(s):  
Alexandrine Morand ◽  
Shailendra Segobin ◽  
Grégory Lecouvey ◽  
Julie Gonneaud ◽  
Francis Eustache ◽  
...  
Keyword(s):  
Diffusion Tensor Imaging ◽  
White Matter ◽  
Prospective Memory ◽  
Gray Matter ◽  
Diffusion Tensor ◽  
Imaging Study ◽  
Age Related ◽  
Young Subjects ◽  
Anterior Prefrontal Cortex ◽  
And Diffusion

Abstract Time-based prospective memory (TBPM) allows us to remember to perform intended actions at a specific time in the future. TBPM is sensitive to the effects of age, but the neural substrates of this decline are still poorly understood. The aim of the present study was thus to better characterize the brain substrates of the age-related decline in TBPM, focusing on macrostructural gray matter and microstructural white matter integrity. We administered a TBPM task to 22 healthy young (26 ± 5.2 years) and 23 older (63 ± 5.9 years) participants, who also underwent volumetric magnetic resonance imaging and diffusion tensor imaging scans. Neuroimaging analyses revealed lower gray matter volumes in several brain areas in older participants, but these did not correlate with TBPM performance. By contrast, an age-related decline in fractional anisotropy in several white-matter tracts connecting frontal and occipital regions did correlate with TBPM performance, whereas there was no significant correlation in healthy young subjects. According to the literature, these tracts are connected to the anterior prefrontal cortex and the thalamus, 2 structures involved in TBPM. These results confirm the view that a disconnection process occurs in aging and contributes to cognitive decline.

The role of white matter damage in late onset bipolar disorder

Maturitas ◽  
2011 ◽  
Vol 70 (2) ◽  
pp. 160-163 ◽  
Author(s):  
Ariadna Besga ◽  
Monica Martinez-Cengotitabengoa ◽  
Itxaso González-Ortega ◽  
Miguel Gutierrez ◽  
Sara Barbeito ◽  
...  
Keyword(s):  
Bipolar Disorder ◽  
White Matter ◽  
Late Onset ◽  
White Matter Damage

Late-onset major depression is associated with age-related white matter lesions in the brainstem

2016 ◽  
Vol 32 (4) ◽  
pp. 446-454 ◽  
Author(s):  
Johannes Schwichtenberg ◽  
Mansour Al-Zghloul ◽  
Hans U. Kerl ◽  
Holger Wenz ◽  
Lucrezia Hausner ◽  
...  
Keyword(s):  
White Matter ◽  
Major Depression ◽  
Late Onset ◽  
White Matter Lesions ◽  
Age Related

T1- and T2-Based MRI Measures of Diffuse Gray Matter and White Matter Damage in Patients with Multiple Sclerosis

2007 ◽  
Vol 17 ◽  
pp. 16S-21S ◽  
Author(s):  
Mohit Neema ◽  
James Stankiewicz ◽  
Ashish Arora ◽  
Venkata S.R. Dandamudi ◽  
Courtney E. Batt ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
White Matter ◽  
Gray Matter ◽  
White Matter Damage ◽  
T1 And T2

scholarly journals Edited Magnetic Resonance Spectroscopy Detects an Age-Related Decline in Nonhuman Primate Brain GABA Levels

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Xuanzi He ◽  
Bang-Bon Koo ◽  
Ronald J. Killiany
Keyword(s):  
White Matter ◽  
Gray Matter ◽  
Posterior Cingulate Cortex ◽  
Resonance Spectroscopy ◽  
Gamma Aminobutyric Acid ◽  
Gaba Level ◽  
Inhibitory Neurotransmitter ◽  
Independent Variables ◽  
Age Related ◽  
The Brain

Recent research had shown a correlation between aging and decreasing Gamma-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the brain. However, how GABA level varies with age in the medial portion of the brain has not yet been studied. The purpose of this study was to investigate the GABA level variation with age focusing on the posterior cingulate cortex, which is the “core hub” of the default mode network. In this study, 14 monkeys between 4 and 21 years were recruited, and MEGA-PRESS MRS was performed to measure GABA levels, in order to explore a potential link between aging and GABA. Our results showed that a correlation between age and GABA+/Creatine ratio was at the edge of significance (r=-0.523,p=0.081). There was also a near-significant trend between gray matter/white matter ratio and the GABA+/Creatine ratio (r=-0.518,p=0.0848). Meanwhile, the correlation between age and grey matter showed no significance (r=-0.028,p=0.93). Therefore, age and gray matter/white matter ratio account for different part ofR-squared (adjustedR-squared = 0.5187) as independent variables for predicting GABA levels. AdjustedR-squared is about 0.5 for two independent variables. These findings suggest that there is internal neurochemical variation of GABA levels in the nonhuman primates associated with normal aging and structural brain decline.

scholarly journals Age-related macular degeneration affects the optic radiation white matter projecting to locations of retinal damage

2018 ◽  
Author(s):  
Shoyo Yoshimine ◽  
Shumpei Ogawa ◽  
Hiroshi Horiguchi ◽  
Masahiko Terao ◽  
Atsushi Miyazaki ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Visual Acuity ◽  
White Matter ◽  
Age Related Macular Degeneration ◽  
Retinal Damage ◽  
Optic Radiation ◽  
Resonance Imaging ◽  
White Matter Damage ◽  
Age Related ◽  
The Impact

ABSTRACTPurposeWe investigated the impact of age-related macular degeneration (AMD) on visual acuity and the visual white matter.MethodsWe combined an adaptive cortical atlas and diffusion-weighted magnetic resonance imaging (dMRI) and tractography to separate optic radiation (OR) projections to different retinal eccentricities in human primary visual cortex. We exploited the known anatomical organization of the OR and clinically relevant data to segment the OR into three primary components projecting to fovea, mid- and far-periphery. We measured white matter tissue properties – (fractional anisotropy, linearity, planarity, sphericity) along the aforementioned three components of the optic radiation to compare AMD patients and controls.ResultsWe found differences in white matter properties specific to OR white matter fascicles projecting to primary visual cortex locations corresponding to the location of retinal damage (fovea). Additionally, we show that the magnitude of white matter properties in AMD patients’ correlates with visual acuity. In sum, we demonstrate a specific relation between visual loss, anatomical location of retinal damage and white matter damage in AMD patients. Importantly, we demonstrate that these changes are so profound that can be detected using magnetic resonance imaging data with clinical resolution. The conserved mapping between retinal and white matter damage suggests that retinal neurodegeneration might be a primary cause of white matter degeneration in AMD patients.ConclusionsThe results highlight the impact of eye disease on brain tissue, a process that may become an important target to monitor during the course of treatment.

Gray matter atrophy cannot be fully explained by white matter damage in patients with MS

2020 ◽  
Vol 27 (1) ◽  
pp. 39-51 ◽  
Author(s):  
Jian Zhang ◽  
Antonio Giorgio ◽  
Claudia Vinciguerra ◽  
Maria Laura Stromillo ◽  
Marco Battaglini ◽  
...  
Keyword(s):  
White Matter ◽  
Gray Matter ◽  
Similar Data ◽  
White Matter Damage ◽  
Lesion Load ◽  
Posterior Cortex ◽  
Data Set ◽  
Close Link ◽  
Random Patterns ◽  
Normal Controls

Background: Source-based morphometry (SBM) was recently used for non-random “patterns” of gray matter (GM) atrophy or white matter (WM) microstructural damage. Objective: To assess whether and to what extent such patterns may be inter-related in MS. Methods: SBM was applied to images of GM concentration and fractional anisotropy (FA) in MS patients ( n = 41, median EDSS = 1) and normal controls (NC, n = 28). The same procedure was repeated on an independent and similar data set (39 MS patients and 13 NC). Results: We found in MS patterns of GM atrophy and reduced FA ( p < 0.05, corrected). Deep GM atrophy was mostly (70%) explained by lesion load in projection tracts and lower FA in posterior corona radiata and thalamic radiation. By contrast, sensorimotor and posterior cortex atrophy was less (50%) dependent from WM damage. All patterns correlated with EDSS ( r from −0.33 to −0.56, p < 0.03) while the only cognition-related correlation was between posterior GM atrophy pattern and processing speed ( r = 0.45, p = 0.014). Reliability analysis showed similar results. Conclusion: In relatively early MS, we found a close link between deep GM atrophy pattern and WM damage while sensorimotor and posterior cortex patterns were partially independent from WM damage and perhaps related to primary mechanisms. Patterns were clinically relevant.

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