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Using diffusion MRI tractography we segmented white matter tracts thought to be related with cognition in a cohort of healthy older people. We registered the tract segmentations to parametric maps of magnetization ratios and T1 relaxation times and used these parameters, as well as fractional anisotropy and mean diffusivity, to characterise the white matter integrity of the tracts. The study of how tract integrity relates to cognition in old age revealed new relationships not shown by diffusion parameters only. This work suggests that a multi-parameter approach could unravel the effects of ageing on the brain and cognition better than the lone use of diffusion MRI.

Estimations on age-related rate of changes of brain tissues have mostly been gathered from cross-sectional MRI studies. A limitation of cross-sectional design is the inability to directly assess intra-individual change. Longitudinal studies on brain tissues and age in large population cohorts are lacking. We compared estimated rates of cross-sectional and longitudinal changes with age in brain tissues in a population-based cohort of 4614 older persons. The longitudinal data show a substantially higher age-related rate of change in tissue volumes when compared to the cross-sectional estimates and show that the cross-sectional data underestimates the rate of change in brain tissues.

VBM analysis of grey matter distribution within the healthy adult brain was undertaken, in a sample of 31 males and 35 females (age range: 20-72 years) to investigate sex differences in the effect of brain ageing. Data were analysed using a full factorial analysis (2x2x2). There were no significant sex by age effects. Within sex regression analyses revealed that females showed age related GM decrements within several frontal regions tending medially, whereas males sowed age related decrements in bilateral structures including IFG (BA44/45). These findings are discussed.

Intensity of white matter lesions (WMLs) on structural MRI may be linked to the severity of underlying white matter damage, and hence to old age cognitive decline. Here we investigate relationships between the volumes of intense (i) and less-intense (Li) WMLs in a unique cohort of ? subjects in whom cognitive ability is available in both youth (11 years) and old age (72-73 years). iWMLs were predominant located in frontal areas, while LiWMLs were mainly located posteriorly. iWMLs had a stronger relationship with cognition than LiWMLs in both youth and old age. These findings support the frontal ageing hypothesis.

To test the correlations of aging, sex, and aortic stenosis (AS) degree with the severity of pre-existing white matter and ischemia-like lesions. Aging was associated with rapidly progressive cerebral ischemic disease; female sex accounted for a 56% increased in lesion volume over men; while the severity of AS did not demonstrate statistical significance in influencing lesion volume, univariate analysis demonstrated an important trend of increasing lesion volume with increasing severity of AS.

We present a novel technique applying probabilistic diffusion tensor tractography on longitudinal data to assess white matter structural integrity in ageing subjects over a period of two years. Our method was able to consistently extract white matter tracts associated with working memory over time and between two ageing cohorts (middle-aged and elderly). Tract connections were found between the fronto-temporal, fronto-parietal and temporo-parietal lobes. Our study suggests a decrease in white matter structural integrity of these tracts with age could be related to the decline in working memory performance.

White matter lesions are a common finding on T2- and FLAIR-weighted MRI scans of older subjects, but their etiology and relationship to cognitive function remains unclear. The aim of this pilot study was to characterize differences in magnetization transfer ratio and spin-lattice relaxation time between macroscopically normal-appearing white matter and white matter lesions in a subset of a unique cohort of aging subjects, the Lothian Birth Cohort 1936.

The present study bridges the gap between midlife hypertension and late-life cognitive impairment, a relationship that has long been documented but remains poorly understood. We demonstrate that midlife hypertension and associated arterial thickening relate to cerebral measures of neuronal health and viability in middle-aged adults with intact cognitive performance.

With menopause, women underwent changes of overall hormones, leading to functional changes of organs. A majority of menopausal women experience some exchanges in sexual function. Using fMRI technique, menopausal a few papers concerning differential brain activation patterns between premenopausal and menopausal women were published. However, it is unclear how brain metabolite change in menopause affects sexual arousal.

The purpose of this study was to investigate the brain metabolic changes associated with visual sexual arousal in premenopausal and menopausal women using functional MR spectroscopy (fMRS).

2007. Motion Detection in Healthy Young, Middle-Aged, and Elderly Adults Using a Water Signal Based Navigator Echo: A ¹H MRS Study

Sarah Andrea Wijtenburg¹, Kathleen L. Fuchs², Virginia I. Simnad³, Jack Knight-Scott<sup>1

1</sup>Radiology, Children's Healthcare of Atlanta, Atlanta, GA, United States; ²Neurology, University of Virginia, Charlottesville, VA, United States; ³Neurology, Evergreen Hospital Medical Center, Kirkland, WA, United States

Here, we build upon our earlier work incorporating a CHESS pulse into a STEAM sequence by presenting a new method for analyzing and interpreting motion data collected from three age groups: healthy young (HY), healthy middle-aged (HM), and healthy elderly (HE). Our results show that listed in increasing order of motion during a ¹H MRS STEAM spectroscopy examination: HY, HM, and HE.

Quantitative assessment of ¹H-MRS metabolite concentrations has the potential to be an in-vivo marker for disease progression and treatment efficacy in pharmaceutical trials. The present study examines cross-site reproducibility of ¹H-MRS metabolite concentrations measured on the same 5 people at 6 sites. Average percent differences of inter and intra-site reproducibility was <10% for n-acetyl-aspartate and myo-Inositol, <7% for creatine, <8% for choline and <21% for glutamate and glutamine. All percent differences between sites were of a similar magnitude increasing confidence in comparing results from across the sites.

Functional connectivity (FC) and the default mode network represents two recent active research directions in fMRI. Previous studies have shown the aging effect in resting FC based on independent component analysis or concurrent task involved fMRI defined region-of-interests (ROIs). No published work has assessed the aging effects on resting FC in the DMN using the seed region based method. To meet this gap, we here report some preliminary results of the aging inter-region FC in the normal brain using resting fMRI and found age-dependent FC decrease in anterior cingulate cortex and posterior cingulate cortex.

We investigated the relationship between in vivo measurement of venous blood T1 and BOLD signal changes during visual stimulation in two groups of young and elderly subjects. There was a significant negative correlation between venous blood T1 and BOLD activation across subjects. Upon including venous blood T1 as a covariate, the differences in BOLD activation between the two age groups weakened, suggesting that aging effects on BOLD fMRI may be partly attributed to baseline hematocrit variations.

This study aims to investigate changes in resting state functional connectivity with increasing age. 40 healthy subjects (aged 20 – 76) participated. Gradient echo EPI images were collected during a Stroop task and active regions were found across the group. The BOLD amplitude in the right middle frontal gyrus (MFG) increased with age, reducing laterality of activation. Partial correlation was used to investigate functional connectivity between bilateral MFG, which was found to increase with age between bilateral MFG in adults aged 40yrs+. Increased connectivity was also associated with improved accuracy, suggesting alterations in functional connectivity may be important for performance.

Resting state networks undergo various age related changes both in strength and spatial distribution. Some occur in adolescence while many changes also occur later in adulthood. A salience network splits without much strength in any age group. These different findings reflect multiple normal ageing processes of the central nervous system.

The steadiness of walking decreases in elderly with advancing age. This study was designed to explore changes in the activation pattern during walking. Healthy young and elderly subjects performed imaginated walking tasks while being scanned. Elderly subjects exhibited stronger and larger activations as compared to younger subjects with a marked increase in the IPL. During imaginated walking, negative BOLD signal changes were only observed in younger, but not in elderly subjects.

The frequency of naming errors increases in normal aging. In this study we examined an elderly cohort of subjects; classified their naming difficulties and correlated this with high resolution structural MRI images. Different regions were structurally correlated for reduced semantic, phonological and visual perception errors, including the inferior temporal lobe, middle temporal lobe, and occipital-parietal regions.

A normal elderly cohort was examined with MRI and a lexical access/semantic priming task. The priming effect (semantically related vs unrelated prime-target pairs), and the word (semantic + unrelated response times) versus non-word targets were calculated. These variables were covaried with the individual subjects’ high resolution MRI images, to investigate any possible structural dependencies. Structures of areas associated with attentional and semantic priming networks were significant when compared against non-word responses, and areas of conceptual object knowledge and familiarity when compared with the priming effect.

The characteristics of the hemodynamic response function underlying the age-related change was investigated to estimate its contribution to the statistical evaluation of fMRI by using motor tasks. It was suggested that the neuronal demanded was augmented to support cognitive processing for motor regulation rather than motor execution itself. Augmented activation in the elderly subjects mostly depended on the increased BOLD signal amplitude between the initial and post-stimulus peaks. It will be recommended to consider the potential bias induced by the non-linear dynamics of HRF to assess the age-related change of brain activation.

GABA and Glx were measured in 28 volunteers using a PRESS-based two step J editing sequence. Two voxels located in the medial prefrontal cortex (MPFC) and the occipital lobe (OCC) were studied. The GABA/Cre ratio was significantly higher (P<0.001) in the OCC (0.115 +/- 0.008) than in the MPFC (0.102 +/- 0.009). Co-edited Glx/Cre ratio was significantly (P<0.001) lower in the OCC (0.0806 +/- 0.006) than in the MPFC (0.0974 +/- 0.009). Our results, combined with previously reported Cre distribution in brain, show that there are significant differences in GABA and Glx between MPFC and OCC.