Cerebral volume loss, cognitive deficit and neuropsychological performance: Comparative measures of brain atrophy: I. Dementia

Abstract

There are several magnetic resonance (MR) imaging methods to measure brain volume and cerebral atrophy; however, the best measure for examining potential relationships between such measures and neuropsychological performance has not been established. Relationships between seven measures of MR derived brain volume or indices of atrophy and neuropsychological performance in the elderly subjects of the population-based Cache County, Utah Study of Aging and Memory (n = 195) were evaluated. The seven MR measures included uncorrected total brain volume (TBV), TBV corrected by total intracranial volume (TICV), TBV corrected by the ratio of the individuals TICV by group TICV (TBVC), a ventricle-to-brain ratio (VBR), total ventricular volume (TVV), TVV corrected by TICV, and a measure of parenchymal volume loss. The cases from the Cache County Study were comprised of elderly individuals classified into one of four subject groups based on a consensus diagnostic process, independent of quantitative MR imaging findings. The groups included subjects with Alzheimer's disease (AD, n = 85), no dementia but mild/ambiguous (M/A) deficits (n = 30), a group of subjects with non-AD dementia or neuropsychiatric disorder including vascular dementia (n = 60), and control subjects (n = 20). Neuropsychological performance was based on the Mini-Mental Status Exam (MMSE) and an expanded neuropsychological test battery (consortium to establish a registry for Alzheimer's disease (CERAD). The results demonstrated that the various quantitative MR measures were highly interrelated and no single measure was statistically superior. However, TBVC, TBV/TICV and VBR consistently exhibited the more robust relationships with neuropsychological performance. These results suggest that a single corrected brain volume measure or index is sufficient in studies examining global MR indicators of cerebral atrophy in relation to cognitive function and recommends use of either TBVC, TBV/TICV, or VBR.

Aging, gender, and the elderly adult brain: An examination of analytical strategies

“…Some researchers use structure volume as the dependent variable, while others use volume ratios; some advocate using intracranial volume (ICV) as a covariate, while others do not. We conducted analyses on age and gender using each of these methods, and report them all in order to facilitate comparisons (see [3,4 for similar approaches). Table 1 presents the demographics of our sample and the number of scans that were available for each brain structure.…”

“…We investigated the rate of volume change in gray and white matter tissue, cerebrospinal fluid, and lesions, as well as the caudate, putamen, and hippocampus. We sought to address several issues (for a similar approach, see [4]): Can we provide precise, quantitative estimates of brain atrophy, laterality, and gender differences? In particular, what is the relation between white-matter decline and aging in an older population?…”

“…Furthermore, given that we were focusing on an elderly population, we predicted that white-matter volumes would be negatively correlated with age as well. We also predicted that the choice of covariate would not substantially change the results of these analyses [4]. For the gender analyses, we predicted that the use of the covariates would make a difference: uncorrected volumes were expected to be larger in men than in women; corrected volumes were expected to be larger in women than in men, with the exception of the hippocampus.…”

Impact of the AGTR1 A1166C polymorphism on subcortical hyperintensities and cognition in healthy older adults

“…The ratio approach corrects for head size on an individual basis (Sanfilipo et al 2004) and has been utilized in previous studies of SH Haley et al 2007;Lane et al 2011;Opherk et al 2014). Previous research comparing this approach with other standardization techniques has revealed minimal to no differences in results, with no statistically superior standardization measure (Bigler et al 2004;Tate et al 2011). …”

Upper cervical spinal cord cross‐sectional area in relapsing remitting multiple sclerosis: Application of a new technique for measuring cross‐sectional area on magnetic resonance images

“…The relatively large number of both controls and patients in our study resulted in greater statistical power, and to improve this further we measured the total intracranial volume (TICV) and used it to eliminate some of the normal population variance in CSA. The TICV is not affected by MS, and was used for normalization purposes in several previous atrophy studies (9,15,16,23,24). We also estimated the statistical power of the study, and the increase in power due to the normalization.…”