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The multivariate normative comparison (MNC) method has been used for identifying cognitive impairment. When participants' cognitive brain domains are evaluated regularly, the longitudinal MNC (LMNC) has been introduced to correct for the intercorrelation among repeated assessments of multiple cognitive domains in the same participant. However, it may not be practical to wait until the end of study for diagnosis. For example, in participants of the Multicenter AIDS Cohort Study (MACS), cognitive functioning has been evaluated repeatedly for more than 35 years. Therefore, it is optimal to identify cognitive impairment at each assessment, while the family-wise error rate (FWER) is controlled with unknown number of assessments in future. In this work, we propose to use the difference of consecutive LMNC test statistics to construct independent tests. Frequency modeling can help predict how many assessments each participant will have, so Bonferroni-type correction can be easily adapted. A chi-squared test is used under the assumption of multivariate normality, and permutation test is proposed where this assumption is violated. We showed through simulation and the MACS data that our method controlled FWER below a predetermined level., (© 2022 John Wiley & Sons Ltd.)

Motivated by the Multicenter AIDS Cohort Study (MACS), we develop classification procedures for cognitive impairment based on longitudinal measures. To control family-wise error, we adapt the cross-sectional multivariate normative comparisons (MNC) method to the longitudinal setting. The cross-sectional MNC was proposed to control family-wise error by measuring the distance between multiple domain scores of a participant and the norms of healthy controls and specifically accounting for intercorrelations among all domain scores. However, in a longitudinal setting where domain scores are recorded multiple times, applying the cross-sectional MNC at each visit will still have inflated family-wise error rate due to multiple testing over repeated visits. Thus, we propose longitudinal MNC procedures that are constructed based on multivariate mixed effects models. A χ 2 test procedure is adapted from the cross-sectional MNC to classify impairment on longitudinal multivariate normal data. Meanwhile, a permutation procedure is proposed to handle skewed data. Through simulations we show that our methods can effectively control family-wise error at a predetermined level. A dataset from a neuropsychological substudy of the MACS is used to illustrate the applications of our proposed classification procedures., (© 2020 John Wiley & Sons, Ltd.)

Declining estrogen levels before, during, and after menopause can affect memory and risk for Alzheimer's disease. Undesirable side effects of hormone variations emphasize a role for hormone therapy (HT) where possible benefits include a delay in the onset of dementia-yet findings are inconsistent. Effects of HT may be mediated by estrogen receptors found throughout the brain. Effects may also depend on lifestyle factors, timing of use, and genetic risk. We studied the impact of self-reported HT use on brain volume in 562 elderly women (71-94 years) with mixed cognitive status while adjusting for aforementioned factors. Covariate-adjusted voxelwise linear regression analyses using a model with 16 predictors showed HT use as positively associated with regional brain volumes, regardless of cognitive status. Examinations of other factors related to menopause, oophorectomy and hysterectomy status independently yielded positive effects on brain volume when added to our model. One interaction term, HTxBMI, out of several examined, revealed significant negative association with overall brain volume, suggesting a greater reduction in brain volume than BMI alone. Our main findings relating HT to regional brain volume were as hypothesized, but some exploratory analyses were not in line with existing hypotheses. Studies suggest lower levels of estrogen resulting from oophorectomy and hysterectomy affect brain volume negatively, and the addition of HT modifies the relation between BMI and brain volume positively. Effects of HT may depend on the age range assessed, motivating studies with a wider age range as well as a randomized design., (© 2020 The Authors. Human Brain Mapping published by Wiley Periodicals LLC.)

Objectives: The aim of the study was to compare the prevalence of comorbid diabetes and depressive symptoms in men living with HIV (MLWH) with that in men without HIV infection and to determine associations between glycaemic control and depressive symptoms., Methods: Participants included 920 MLWH and 840 men without HIV infection from the Multicenter AIDS Cohort Study (MACS) with available data regarding glycaemic status [categorized as normal for fasting blood glucose (FBG) < 100 mg/dL, prediabetes for FBG 100-125 mg/dL, and diabetes, defined by self-report, diabetes medication use or FBG ≥ 126 mg/dL on at least two consecutive visits, with diabetes classified as controlled if Hemoglobin A1c (HbA1C) < 7.5% and uncontrolled if HbA1C ≥ 7.5%]. Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression (CES-D) score, with CES-D ≥ 16 scores classified as elevated depressive symptoms. A modified Poisson regression model with robust variance was used and adjusted for covariates including HIV serostatus., Results: Compared to men without HIV infection, MLWH had a higher mean CES-D score, but a similar prevalence of diabetes (11.3% versus 12.8%, respectively; P = 0.33). The concomitant prevalence of diabetes and elevated depressive symptoms did not differ by HIV serostatus (P = 0.215). In an adjusted analysis, men with uncontrolled diabetes had a greater prevalence of depressive symptoms compared to men with normoglycaemia (prevalence ratio = 1.43; 95% confidence interval 1.11, 1.84). The association between glycaemic status and depressive symptoms did not differ by HIV serostatus (P = 0.22 for interaction)., Conclusions: Both controlled and uncontrolled diabetes were independently associated with a greater prevalence of depressive symptoms, regardless of HIV serostatus. These results highlight the importance of identifying depression in people with diabetes., (© 2020 British HIV Association.)

We study regularized estimation in high-dimensional longitudinal classification problems, using the lasso and fused lasso regularizers. The constructed coefficient estimates are piecewise constant across the time dimension in the longitudinal problem, with adaptively selected change points (break points). We present an efficient algorithm for computing such estimates, based on proximal gradient descent. We apply our proposed technique to a longitudinal data set on Alzheimer's disease from the Cardiovascular Health Study Cognition Study. Using data analysis and a simulation study, we motivate and demonstrate several practical considerations such as the selection of tuning parameters and the assessment of model stability. While race, gender, vascular and heart disease, lack of caregivers, and deterioration of learning and memory are all important predictors of dementia, we also find that these risk factors become more relevant in the later stages of life., (© 2019 John Wiley & Sons, Ltd.)

Normal human aging is accompanied by progressive brain tissue loss and cognitive decline; however, several factors are thought to influence brain aging. We applied tensor-based morphometry to high-resolution brain MRI scans to determine whether educational level or physical activity was associated with brain tissue volumes in the elderly, particularly in regions susceptible to age-related atrophy. We mapped the 3D profile of brain volume differences in 226 healthy elderly subjects (130F/96M; 77.9 ± 3.6 SD years) from the Cardiovascular Health Study-Cognition Study. Statistical maps revealed the 3D profile of brain regions whose volumes were associated with educational level and physical activity (based on leisure-time energy expenditure). After controlling for age, sex, and physical activity, higher educational levels were associated with ~2-3% greater tissue volumes, on average, in the temporal lobe gray matter. After controlling for age, sex, and education, greater physical activity was associated with ~2-2.5% greater average tissue volumes in the white matter of the corona radiata extending into the parietal-occipital junction. Body mass index (BMI) was highly correlated with both education and physical activity, so we examined BMI as a contributing factor by including physical activity, education, and BMI in the same model; only BMI effects remained significant. This is one of the largest MRI studies of factors influencing structural brain aging, and BMI may be a key factor explaining the observed relationship between education, physical activity, and brain structure. Independent contributions to brain structure could not be teased apart as all these factors were highly correlated with one another., (Copyright © 2010 Wiley-Liss, Inc.)

Obesity is associated with increased risk for cardiovascular health problems including diabetes, hypertension, and stroke. These cardiovascular afflictions increase risk for cognitive decline and dementia, but it is unknown whether these factors, specifically obesity and Type II diabetes, are associated with specific patterns of brain atrophy. We used tensor-based morphometry (TBM) to examine gray matter (GM) and white matter (WM) volume differences in 94 elderly subjects who remained cognitively normal for at least 5 years after their scan. Bivariate analyses with corrections for multiple comparisons strongly linked body mass index (BMI), fasting plasma insulin (FPI) levels, and Type II Diabetes Mellitus (DM2) with atrophy in frontal, temporal, and subcortical brain regions. A multiple regression model, also correcting for multiple comparisons, revealed that BMI was still negatively correlated with brain atrophy (FDR <5%), while DM2 and FPI were no longer associated with any volume differences. In an Analysis of Covariance (ANCOVA) model controlling for age, gender, and race, obese subjects with a high BMI (BMI > 30) showed atrophy in the frontal lobes, anterior cingulate gyrus, hippocampus, and thalamus compared with individuals with a normal BMI (18.5-25). Overweight subjects (BMI: 25-30) had atrophy in the basal ganglia and corona radiata of the WM. Overall brain volume did not differ between overweight and obese persons. Higher BMI was associated with lower brain volumes in overweight and obese elderly subjects. Obesity is therefore associated with detectable brain volume deficits in cognitively normal elderly subjects., (2009 Wiley-Liss, Inc.)

Introduction: Arterial spin labeling (ASL) is a safe, noninvasive imaging method for evaluating cerebral blood flow (rCBF). The purpose of this article is to present ASL imaging features of 38 elderly cognitively normals (CN) with their rCBF values and an averaged profile of targeted anatomic regions rCBF values., Methods: Thirty-eight CN underwent MR imaging especially ASL with voxel morphometric techniques fusing the MR anatomical and ASL images to a standard reference brain (colin27). The ASL images were fused to echo planar images, which were then coregistered to high-resolution anatomical SPGR images. rCBF was calculated per region of interest using a modified continuous arterial spin labeling (CASL) convolutional method. Anatomical regions were selected and identified by the Talairach atlas in SPM2., Results: We identified areas of decreased and increased perfusion (compared to the averaged rCBF of all 38 CN) corresponding to decreased and increased quantified rCBF. The most common sites for decreased perfusion were precuneus (53%), superior temporal (48%), and orbitofrontal (37%), and for increased perfusion the caudate (39%), posterior cingulate (34%), anterior cingulate (32%), and amygdala (32%)., Conclusion: There are regional variations in rCBF both increased and decreased with the posterior cingulate and precuneus cortex showing the highest averaged values and signal intensity (bright spots). These variations represent the normal profile of a CN elderly brain, with higher perfusion in areas associated with cognition, memory, and behavior. It is necessary to understand these normal variations in order to determine if there are perfusion changes in ASL detected in neurodegenerative disorders such as Alzheimer's disease.

Background and Purpose: This study investigated the association of medial temporal lobe (MTL) atrophy and cerebrovascular disease (white matter hyperintensities [WMH], subclinical infarcts) with the risk of developing Alzheimer's disease (AD) among cognitively normal older adults., Methods: Risk of developing AD was examined for 155 cognitively normal older adults (77.4 years, 60% women, 81% white). The MTL volumes and the presence of WMH and of subclinical infarcts were determined from brain magnetic resonance imaging (MRI) at the beginning of the study. Follow-up cognitive evaluations (average 4.3 years) identified those who developed AD., Results: The presence of either MTL atrophy or subclinical infarcts was independently and significantly associated with a greater risk to develop AD (OR [95% CI]: 4.4 [1.5, 12.3] and 2.7 [1.0, 7.1], respectively). In addition, those participants with both MTL atrophy and at least one brain infarct had a 7-fold increase in the risk of developing AD (OR [95% CI]: 7.0 [1.5, 33.1]), compared to those who had neither of these conditions., Conclusions: In cognitively normal older adults, markers of neurodegeneration (as reflected by MTL atrophy) and of cerebrovascular disease (as reflected by infarcts on MRI) independently contribute to the risk to develop AD.

The objective of this study is to examine the risk factors associated with the development of sensory neuropathy in human immunodeficiency virus (HIV)-infected patients in 292 HIV+ patients recruited through a community-based sentinel survey. We determined the clinical and treatment factors associated with the presence of peripheral sensory neuropathy in HIV+ subjects at baseline examination, and at 1-year follow-up. Baseline examination was assessed with a logistic regression analysis controlling for age, education level, history of drug/alcohol use, and anti-retroviral treatment. The risk of developing new peripheral neuropathy at follow-up was determined using a Cox proportional hazard model analysis. At study entry, neuropathy (n=64) was associated with acquired immunodeficiency syndrome (AIDS), nucleoside analogue reverse transcriptase inhibitors (NRTI) (i.e. ddC), and history of alcohol abuse. After 1-year follow-up, the development of neuropathy was predicted by AIDS, age (older subjects), and NRTI use. These findings indicated that AIDS, age, alcohol abuse/dependence, and anti-retroviral medication use are important predictors of motor/sensory peripheral neuropathy in the HIV infection. The peripheral neurotoxic effect of anti-retroviral medication should be taken into account in the design of long-term therapies.

We examined the neurological differences between human immunodeficiency virus (HIV)-infected men (n = 193) and women (n = 41) receiving primary medical care. There was no difference between men and women in the rate of HIV-related neurological syndromes (i.e. polyneuropathy, myelopathy, myopathy, HIV- dementia [HAD]). A logistic regression analysis indicated that low CD4+ cell count predicted all neurological syndromes. In addition, HAD was predicted by intravenous-drug use and lower education level, while neuropathy was associated with older age and with race. These findings indicate that there are no differences in the rate of neuropsychiatric disorders attributable to gender. The presence of other factors (e.g. drug abuse) could explain previously reported gender differences in neurological manifestations of HIV infection., (Copyright 1999 Lippincott Williams & Wilkins.)

The purpose of this study was to examine changes in regional cerebral blood flow (rCBF) using positron emission tomography (PET) during overt word and nonword reading tasks to determine structures involved in semantic processing. Ten young, healthy, right-handed subjects were scanned 12 times, twice in each of six specific conditions. Blood flow was measured by 15O-water using standard PET imaging technology. The rCBFs during different cognitive conditions were compared by using analysis of covariance (SPM94), which resulted in three-dimensional maps of those brain regions more active in one condition relative to another. When the subjects read aloud words with difficult or unusual grapheme-phoneme translations (i.e., third-order approximation to English or irregularly spelled real words), increases in activation were seen in the inferior frontal cortex. When subjects were reading aloud regular and irregular words (which had important semantic components relative to nonwords), activation of the fusiform gyrus was seen. These data are broadly consistent with brain regions generally associated with reading based on other neuropsychological paradigms, and they emphasize the multicomponent aspects of this complex cognitive process.

The functional neuroanatomy of verbal memory was investigated using verbal free recall during H2 (15) O positron emission tomography (PET). Twelve young (25-40 years old) normal control subjects participated in eight scans during a single scanning session during which they performed three memory tasks differing by word list length. Four subjects also had scans during a "rest" condition. Temporal lobe activation was observed during all tasks, including single-word repetition. The frontal cortices, specifically Brodmann areas 9 and 10, were activated only when the recall word lists exceeded the memory spans (i. e., 12 and 15 words). Activation was also observed in the anterior cingulate cortex (BA24 and BA32). These data, obtained using a within-subject design, extend previously reported findings that used mixed within-and between-subject designs and demonstrate important functional components of normal auditoryverbal short-term memory. © 1994 Wiley-Liss, Inc., (Copyright © 1994 Wiley-Liss, Inc.)