Age effects on hippocampal structural changes in old men: The HAAS

Abstract

Understanding the variability of the hippocampus in human brain research is essential. The effect of age on the hippocampus has been explored in several studies that have been focused on either normal aging or neural degeneration. Shape analysis of magnetic resonance imaging (MRI) provides morphological measures for brain structures. This study further investigates the age effects on hippocampal morphology in three groups (104 normal controls, 24 Alzheimer's disease (AD) and 14 vascular dementia (VaD) patients). By utilizing a parametric shape analysis of hippocampal MRI scans, each individual distance map is generated and analyzed statistically. Specifically, after eliminating similarity parameters (rotation, translation, and scaling) effects for each hippocampus, an individual distance map is generated from parametric hippocampal surfaces and medial axes. Then statistical methods, including regression, and permutation tests, are applied to detect the differences in hippocampal distance maps and volumes under the effect of age in each group. Statistical analyses reveal that the loss of hippocampal volume and changes in shape are more significantly related to aging in the control group than in AD/VaD. The results also show that the asymmetry of hippocampus in healthy subjects is greater than that in either of the disease groups. Our study shows that 3D statistical shape analysis could enhance the understanding of age effects on local areas of hippocampi. However, the sample sizes of disease groups are relatively low; further studies with more AD/VaD data are needed.

Bilateral Distribution of Oxytocinase Activity in the Medial Prefrontal Cortex of Spontaneously Hypertensive Rats with Experimental Hemiparkinsonism

“…Most importantly, there is a remarkable lower level of left predominance in sham hypertensive controls (figures 2 and 3), compared with the high one observed in sham normotensive controls (figures 4 and 5). This is in agreement with the reduction of the asymmetry observed in prefrontal cortex and hippocampus in ADHD (Shaw et al, 2009) and during aging and vascular dementia compared to healthy subjects (Xu et al, 2008;Vallesi et al, 2010;Bergerbest et al, 2009). Indeed, disruption of physiological asymmetry has been involved in the pathogenesis of cognitive disorders such as ADHD.…”

“…However, in ADHD, while the posterior component of this bilateral development was intact, the prefrontal one was lost (Shaw et al, 2009). The morphological asymmetry of hippocampus in healthy subjects, assessed by magnetic resonance imaging, is greater than that in Alzheimer's disease and in patients with vascular dementia (Xu et al, 2008). Studying the effects of age on the asymmetry of the motor system, Vallesi et al (2010) reported that older adults showed a more symmetric pattern than younger subjects.…”

“…These animals present abnormal dopaminergic transmission and altered neuronal dendrite morphology of the mPFC (Sánchez et al, 2011). Therefore, there exists a connection between hypertension, vascular dementia, cognitive impairment and a modification of the basal brain asymmetry (Xu et al, 2008;Vallesi et al, 2010;Bergerbest et al, 2009). In the ADHD, characterized by impaired sustained attention, impulsivity and hyperactivity, a disruption of the physiological cortical asymmetry has been implicated in its pathogenesis (Shaw et al, 2009).…”

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

“…The above results support the view that there is possibly an increase in the vulnerability of temporolimbic brain structures to age-related changes in advanced stages of elderly life (most evidently in male subjects), and atrophy of such regions should be seen as compatible with normal brain aging. 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.…”

Bilingualism at the core of the brain. Structural differences between bilinguals and monolinguals revealed by subcortical shape analysis

“…However, at the subcortical level, it was not until the advent of shape analysis techniques (e.g., Patenaude et al 2011) that successfully estimating regional shape variations in subcortical structures with high anatomical precision was possible. This approach has been mainly applied to unveil abnormal subcortical morphology in mental disorders or disease (Coscia et al 2009;Harms et al 2007;Kang et al 2008;McKeown et al 2008;Qiu et al 2008;Xu et al 2008) but recently also to understand the role of subcortical shape in high-order cognition in healthy populations (Burgaleta et al 2013b). …”