A quantitative analysis of CT and cognitive measures in normal aging and Alzheimer's disease

Abstract

Abstract. Patients with presumptive Alzheimer's disease (AD) and healthy community volunteers received computed tomographic (CT) brain scans and cognitive tests. The CT scans were quantitatively analyzed with a semiautomated thresholding technique to derive volumetric measures of cerebrospinal fluid (CSF)-to-tissue ratios in six regions of interest (ROIs): lateral ventricles, vertex sulci, frontal sulci, Sylvian fissures, parieto-occipital sulci, and third ventricle. Regression analysis was performed on CT data from 85 older volunteers (ages 51-82) to generate age norms for each ROI. Within this group, tissue loss, as measured by the 940 CSF in each ROI, was highly correlated with age, although each ROI showed different rates of change over age. For all ROIs, the AD group had significantly more tissue loss than expected in normal aging. In addition, AD patients with a presenescent onset (before age 65) tended to have greater vertex sulcal and frontal sulcal tissue reduction than AD patients with a senescent onset (age 65 or after). When regional tissue reduction, corrected for age, was correlated with cognitive test scores, two sets of double dissociations emerged within the AD group: large CT z scores (i.e., decreased tissue and increased CSF) of frontal sulci, but not of the third ventricle, correlated with low Comprehension and Boston Naming Test scores, whereas large CT z scores of the third ventricle, but not of the frontal sulci, correlated with low scores on Digit Symbol and Picture Arrangement. These results suggest that heterogeneity of structural and functional integrity exists among patients with AD.Key Words. Brain imaging, aging, Alzheimer's disease, brain-behavior relationships.The analysis of brain X-ray computed tomography (CT) has evolved from qualitative to quantitative approaches and from linear to volumetric measurement. A recently developed quantitative and volumetric method for analyzing brain CT was first used to describe brain changes associated with normal aging (Pfefferbaum et al.,Adolf Pfefferbaum, M.D

Cognitive and Physiologic Correlates of Subclinical Structural Brain Disease in Elderly Healthy Control Subjects

“…There was a regional difference for atrophy, with greater promi-nence over the posterior brain regions, both cortically and centrally; in contrast, white-matter changes did not show a regional difference. These findings are consistent with prior reports of atrophy and aging in healthy subjects, 56,57 but extend them with the finding of regional differences. The regional prominence of posterior atrophy with age in healthy subjects is, to our knowledge, a new finding and is particularly intriguing given that Alzheimer disease is commonly associated with atrophy and hypometabolism in posterior regions.…”

Brain parenchymal changes during normal aging in domestic cats

“…The significant reduction of the thickness of the interthalamic adhesion in geriatric cats in this study suggests the occurrence of atrophy of this structure, which is attributed not only to cell loss, but also to compaction and cell retraction in humans (Turlejski & Djavadian 2012). These findings do not corroborate the results found in humans by some authors (Jernigan et al 2001), however, they are consistent with data reported by most studies, which detected volumetric reduction of the thalamus as advancing age in humans (Pfefferbaum et al 1990, 2013, Walhovd et al 2005, Van der Elst et al 2007, Fjell et al 2009, Walhovd et al 2011.…”

The Relationship Between Gray Matter Morphometry and Neuropsychological Performance in a Large Sample of Cognitively Healthy Adults

“…These covariates were important elements of the model because previous research has demonstrated that age, education and gender are related to aspects of cognition (Buckner 2004;Coffey et al 2001;Salthouse 1996), and age is also related to gray matter volume Good et al 2001;Lemaitre et al 2005;Murphy et al 1992;Pfefferbaum et al 1990;Raz et al 1997;Salat et al 1999;Thompson et al 2003). That the findings observed here were predominantly frontal does not imply that other areas are not involved.…”