Sexually dimorphic differences in angiogenesis markers predict brain aging trajectories

Aberrant angiogenesis could contribute to cognitive impairment, representing a therapeutic target for preventing dementia. However, most angiogenesis studies focus on model organisms. To test the relevance of angiogenesis to human cognitive aging, we evaluated associations of circulating blood markers of angiogenesis with brain aging trajectories in two deeply phenotyped human cohorts (n=435, age 74 + 9) with longitudinal cognitive assessments, biospecimens, structural brain imaging, and clinical data. Machine learning and traditional statistics revealed sex dimorphic associations of plasma angiogenic growth factors with brain aging outcomes. Specifically, angiogenesis is associated with higher executive function and less brain atrophy in younger women (not men), a directionality of association that reverses around age 75. Higher levels of basic fibroblast growth factor, known for pleiotropic effects on multiple cell types, predicted favorable cognitive trajectories. This work demonstrates the relevance of angiogenesis to brain aging with important therapeutic implications for vascular cognitive impairment and dementia.

Abstract T P412: Cerebral Microbleeds and Cognition: The Framingham Heart Study

Objective: To study the association of cerebral microbleeds (CMB) on MRI and performance on a comprehensive neuropsychological test battery in a community based cohort free of stroke and dementia.

Background: CMB represent hemorrhage-prone cerebral small vessel disease (SVD) and have been related to increased risk of dementia. In non-demented individuals, CMB may negatively affect cognition and the pattern of impaired cognitive performance may differ according to lesion topography.

Methods: We evaluated 1744 Framingham Offspring Study participants (mean age 64.6 years, 54% women) attending a baseline examination (1998-2008), who had brain MRI allowing for CMB detection and underwent concurrent NP testing. Using multivariable linear regression we related CMB presence overall and stratified by brain location (lobar, deep or mixed) to performance on NP tests representing cognitive domains including memory, executive function, abstraction, language and visuospatial function.

Results: CMB were observed in 7.7% of subjects (66% lobar, 20% deep, 14% mixed). After adjustment for sex, age, level of education and MRI markers of ischemic small vessel disease, presence of any CMB was associated with impaired performance on tests of abstraction (β -0.71, p=0.02) and language (β -0.13, p=0.04). The associations were attenuated after adjustment for vascular risk factors (hypertension, diabetes, smoking, prevalent cardiovascular disease). Lobar CMB showed similar marginal associations (p=0.05), also attenuated after adjustment for vascular risk factors. Mixed location CMB were associated with tests of executive function, an association that remained significant after adjustment for MRI markers of ischemic SVD and vascular risk factors (β-0.12, p= 0.02). CMB in only deep location did not show any significant association with NP test performance.

Conclusions: CMB were associated with lower cognitive performance in a community-based sample of middle-aged adults. Our findings are limited given the cross sectional study design and small sample in subgroups of deep and mixed CMB, but concur with studies suggesting a negative impact of CMB on cognition, and expand prior studies by showing that the relations are independent of ischemic cerebral SVD.

The contributions of MRI-based measures of gray matter, white matter hyperintensity, and white matter integrity to late-life cognition

BACKGROUND AND PURPOSE

GM volume, WMH volume, and FA are each associated with cognition; however, few studies have detected whether these 3 different types of MR imaging measurements exert independent or additive effects on cognitive performance. To detect their extent of contribution to cognitive performance, we explored the independent and additive contributions of GM atrophy, white matter injury, and white matter integrity to cognition in elderly patients.

MATERIALS AND METHODS

Two hundred and 9 elderly patients participated in the study: 97 were CN adults, 65 had MCI, and 47 had dementia. We measured GM on T1-weighted MR imaging, WMH on FLAIR, and FA on DTI, along with psychometrically matched measures of 4 domains of cognitive performance, including semantic memory, episodic memory, executive function, and spatial abilities.

RESULTS

As expected, patients with dementia performed significantly more poorly in all 4 cognitive domains, whereas patients with MCI performed generally less poorly than dementia patients, though considerable overlap in performance was present across groups. GM, FA, and WMH each differed significantly between diagnostic groups and were associated with cognitive measures. In multivariate models that included all 3 MR imaging measures (GM, WMH, and FA), GM volume was the strongest determinant of cognitive performance.

CONCLUSIONS

These results strongly suggest that MR imaging measures of GM are more closely associated with cognitive function than WM measures across a broad range of cognitive and functional impairment.

FLAIR and diffusion MRI signals are independent predictors of white matter hyperintensities

BACKGROUND AND PURPOSE

WMH, associated with cognitive decline and cardiovascular risk factors, may represent only the extreme end of a more widespread continuous WM injury process that progresses during aging and is poorly understood. We investigated the ability of FLAIR and DTI to characterize the longitudinal course of WMH development.

MATERIALS AND METHODS

One hundred nineteen participants (mean age, 74.5 ± 7.4), including cognitively healthy elders and subjects diagnosed with Alzheimer disease and mild cognitive impairment, received a comprehensive clinical evaluation and brain MR imaging, including FLAIR and DTI on 2 dates. The risk for each baseline normal-appearing WM voxel to convert into WMH was modeled as a function of baseline FA (model M1) and both baseline FA and standardized FLAIR (M2). Sensitivity, specificity, accuracy, and AUC for predicting conversion to WMH were compared between models.

RESULTS

Independent of clinical diagnosis, lower baseline FA (P < .001, both models) and higher baseline FLAIR intensity (P < .001, M2) were independently associated with increased risk for conversion from normal WM to WMH. M1 exhibited higher sensitivity but lower specificity, accuracy, and AUC compared with M2.

CONCLUSIONS

These findings provide further evidence that WMH result from a continuous process of WM degeneration with time. Stepwise decreases in WM integrity as measured by both DTI and FLAIR were independently associated with stepwise increases in WMH risk, emphasizing that these modalities may provide complementary information for understanding the time course of aging-associated WM degeneration.

Memory after silent stroke: hippocampus and infarcts both matter

OBJECTIVE

Memory decline commonly occurs among elderly individuals. This observation is often attributed to early neurodegenerative changes in the hippocampus and related brain regions. However, the contribution of vascular lesions, such as brain infarcts, to hippocampal integrity and age-associated memory decline remains unclear.

METHODS

We studied 658 elderly participants without dementia from a prospective, community-based study on aging and dementia who received high-resolution structural MRI. Cortical and subcortical infarcts were identified, and hippocampal and relative brain volumes were calculated following standard protocols. Summary scores reflecting performance on tasks of memory, language, processing speed, and visuospatial function were derived from a comprehensive neuropsychological battery. We used multiple regression analyses to relate cortical and subcortical infarcts, hippocampal and relative brain volume, to measures of cognitive performance in domains of memory, language, processing speed, and visuospatial ability.

RESULTS

Presence of brain infarcts was associated with a smaller hippocampus. Smaller hippocampus volume was associated with poorer memory specifically. Brain infarcts were associated with poorer memory and cognitive performance in all other domains, which was independent of hippocampus volume.

CONCLUSIONS

Both hippocampal volume and brain infarcts independently contribute to memory performance in elderly individuals without dementia. Given that age-associated neurodegenerative conditions, such as Alzheimer disease, are defined primarily by impairment in memory, these findings have clinical implications for prevention and for identification of pathogenic factors associated with disease symptomatology.

MRI non-uniformity correction through interleaved bias estimation and B-spline deformation with a template

We propose a template-based method for correcting field inhomogeneity biases in magnetic resonance images (MRI) of the human brain. At each algorithm iteration, the update of a B-spline deformation between an unbiased template image and the subject image is interleaved with estimation of a bias field based on the current template-to-image alignment. The bias field is modeled using a spatially smooth thin-plate spline interpolation based on ratios of local image patch intensity means between the deformed template and subject images. This is used to iteratively correct subject image intensities which are then used to improve the template-to-image deformation. Experiments on synthetic and real data sets of images with and without Alzheimer's disease suggest that the approach may have advantages over the popular N3 technique for modeling bias fields and narrowing intensity ranges of gray matter, white matter, and cerebrospinal fluid. This bias field correction method has the potential to be more accurate than correction schemes based solely on intrinsic image properties or hypothetical image intensity distributions.

Midlife vascular risk factor exposure accelerates structural brain aging and cognitive decline

OBJECTIVE

Our aim was to test the association of vascular risk factor exposure in midlife with progression of MRI markers of brain aging and measures of cognitive decline.

METHODS

A total of 1,352 participants without dementia from the prospective Framingham Offspring Cohort Study were examined. Multivariable linear and logistic regressions were implemented to study the association of midlife vascular risk factor exposure with longitudinal change in white matter hyperintensity volume (WMHV), total brain volume (TBV), temporal horn volume, logical memory delayed recall, visual reproductions delayed-recall (VR-d), and Trail-Making Test B-A (TrB-A) performance a decade later.

RESULTS

Hypertension in midlife was associated with accelerated WMHV progression (p < 0.001) and worsening executive function (TrB-A score; p = 0.012). Midlife diabetes and smoking were associated with a more rapid increase in temporal horn volume, a surrogate marker of accelerated hippocampal atrophy (p = 0.017 and p = 0.008, respectively). Midlife smoking also predicted a more marked decrease in total brain volume (p = 0.025) and increased risk of extensive change in WMHV (odds ratio = 1.58 [95%confidence interval 1.07-2.33], p = 0.021). Obesity in midlife was associated with an increased risk of being in the top quartile of change in executive function (1.39 [1.02-1.88], p = 0.035) and increasing waist-to-hip ratio was associated with marked decline in TBV (10.81 [1.44-81.01], p = 0.021). Longitudinal changes in brain structure were significantly correlated with decline in memory and executive function.

CONCLUSIONS

Midlife hypertension, diabetes, smoking, and obesity were associated with an increased rate of progression of vascular brain injury, global and hippocampal atrophy, and decline in executive function a decade later.

Subtypes based on cerebrospinal fluid and magnetic resonance imaging markers in normal elderly predict cognitive decline

Cerebrospinal fluid (CSF) and structural magnetic resonance imaging (MRI) show patterns of change in Alzheimer's disease (AD) that precede dementia. The Alzheimer's Disease Neuroimaging Initiative (ADNI) studied normal controls (NC), subjects with mild cognitive impairment (MCI), and subjects with AD to identify patterns of biomarkers to aid in early diagnosis and effective treatment of AD. Two hundred twenty-two NC underwent baseline MRI and clinical examination at baseline and at least one follow-up. One hundred twelve also provided CSF at baseline. Unsupervised clustering based on initial CSF and MRI measures was used to identify clusters of participants with similar profiles. Repeated measures regression modeling assessed the relationship of individual measures, and of cluster membership, to cognitive change over 3 years. Most individuals showed little cognitive change. Individual biomarkers had limited predictive value for cognitive decline, but membership in the cluster with the most extreme profile was associated with more rapid decline in ADAS-cog. Subtypes among NC based on multiple biomarkers may represent the earliest stages of subclinical cognitive decline and AD.

Psychological symptoms correlate with reduced hippocampal volume in fragile X premutation carriers

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder occurring in male and occasional female carriers of a premutation expansion (55-200 CGG repeats) of the fragile X mental retardation 1 gene (FMR1). This study assessed the relationship between hippocampal volume and psychological symptoms in carriers, both with and without FXTAS, and controls. Volumetric MRI measures, clinical staging, cognitive testing, molecular analysis, and measures of psychological symptoms were performed for female premutation carriers both with FXTAS (n = 16, age: 57.50 + or - 12.46) and without FXTAS (n = 17, age: 44.94 + or - 11.23), in genetically normal female controls (n = 8, age: 50.63 + or - 11.43), male carriers with FXTAS (n = 34, age: 66.44 + or - 6.77) and without FXTAS (n = 21, age: 52.38 + or - 12.11), and genetically normal male controls (n = 30, age: 57.20 + or - 14.12). We examined the relationship between psychological symptom severity and hippocampal volume, as well as correlations with molecular data. We found a significant negative correlation between total hippocampal volume and anxiety in female carriers, with and without FXTAS. This finding was mainly driven by the significant negative correlation between right hippocampal volume and anxiety. Other anxiety-related subscales also correlated with the right hippocampus in females. In male carriers with and without FXTAS, only paranoid ideation negatively correlated with hippocampal volume. Female premutation carriers demonstrated a negative association between hippocampal volume and the severity of anxiety-related psychological symptoms. Though the presentation of FXTAS symptoms is less common in females, anxiety-related problems are common both prior to and after the onset of FXTAS, and may be related to hippocampal changes.

Is staging beneficial for Fowler-Stephens orchiopexy? A systematic review

PURPOSE

Fowler and Stephens showed that by dividing the spermatic vessels a high intra-abdominal testis could be placed in the scrotum. Testicular atrophy is a potential complication of this technique. We conducted a systematic review to determine whether single or 2-stage Fowler-Stephens orchiopexy results in better testicular viability.

MATERIALS AND METHODS

We searched electronic databases, clinical trial registries and gray literature. We included reports describing boys younger than 18 years with a primary outcome of "testicular viability and position." We performed a meta-analysis using random effects models. Heterogeneity was assessed using forest plot and I(2) statistic.

RESULTS

We identified 1,807 citations and included 61 articles. Single stage Fowler-Stephens orchiopexy was discussed in 9 articles, a 2-stage procedure in 36 and both approaches in 16. There were no randomized controlled trials, and most studies were cohort or case series. The pooled estimate of success rates was 80% for single stage Fowler-Stephens orchiopexy (95% CI 75 to 86) and 85% for 2-stage Fowler-Stephens orchiopexy (95% CI 81 to 90). The pooled odds ratio of single stage vs 2-stage Fowler-Stephens orchiopexy was 2.0 (95% CI 1.1 to 3.9) favoring the 2-stage procedure. There was no difference in the success rate between laparoscopic and open techniques in either single or 2-stage Fowler-Stephens orchiopexy. There was no evidence of asymmetry on the funnel plot. There were no complications reported with single stage, while ileus, hematoma and infection were the most common complications with 2-stage Fowler-Stephens orchiopexy.

CONCLUSIONS

Both techniques have a fairly high success rate but 2-stage Fowler-Stephens orchiopexy appears to carry a higher rate of success than the single stage approach (85% vs 80%, OR 2 in favor of 2-stage). Laparoscopic and open techniques had the same success rate. However, the level of evidence of the studies was low, and a study of a more robust design, such as a randomized controlled trial, should be performed.

Regional pattern of white matter microstructural changes in normal aging, MCI, and AD

OBJECTIVE

To cross-sectionally compare the regional white matter fractional anisotropy (FA) of cognitively normal (CN) older individuals and patients with mild cognitive impairment (MCI) and Alzheimer disease (AD), separately focusing on the normal-appearing white matter (NAWM) and white matter hyperintensities (WMH), and to test the independent effects of presumed degenerative and vascular process on FA differences.

METHODS

Forty-seven patients with AD, 73 patients with MCI, and 95 CN subjects received diffusion tensor imaging and vascular risk evaluation. To properly control normal regional variability of FA, we divided cerebral white matter into 4 strata as measured from a series of young healthy individuals (H1 = highest; H2 = intermediate high; H3 = intermediate low; H4 = lowest anisotropy stratum).

RESULTS

For overall cerebral white matter, patients with AD had significantly lower FA than CN individuals or patients with MCI in the regions with higher baseline anisotropy (H1, H2, and H3), corresponding to long corticocortical association fibers, but not in H4, which mostly includes heterogeneously oriented fibers. Vascular risk showed significant independent effects on FA in all strata except H1, which corresponds to the genu and splenium of the corpus callosum. Similar results were found within NAWM. FA in WMH was significantly lower than NAWM across all strata but was not associated with diagnosis or vascular risk.

CONCLUSIONS

Both vascular and Alzheimer disease degenerative process contribute to microstructural injury of cerebral white matter across the spectrum of cognitive ability and have different region-specific injury patterns.

Subclinical cerebrovascular disease in mild cognitive impairment

BACKGROUND

Cerebrovascular disease (CVD) may contribute to mild cognitive impairment (MCI). We sought to determine the relation of white matter hyperintensity (WMH) volume and infarcts in brain MRI to MCI in a community-based sample.

METHODS

A total of 679 elderly persons without dementia underwent brain MRI. WMH and infarcts were quantified using research methods. WMH was adjusted for total cranial volume. The Petersen criteria were used to define MCI. MCI was further subclassified into amnestic and non-amnestic. We used logistic regression to relate WMH and infarcts to prevalent MCI.

RESULTS

WMH were associated with amnestic MCI (odds ratio [OR] = 1.9; 95% confidence interval [CI] 1.1, 3.4) but not non-amnestic MCI (OR = 1.2; 95% CI 0.4, 1.6) after adjusting for age, gender, ethnic group, education, and APOE-epsilon4. Infarcts were more strongly associated with non-amnestic MCI (OR = 2.7; 95% CI 1.5, 4.8) than amnestic MCI (OR = 1.4; 95% CI 0.9, 2.3). In secondary analyses using continuous cognitive scores as outcomes, WMH, but not infarcts, were related to memory, while infarcts were more strongly related with non-amnestic domains.

CONCLUSION

White matter hyperintensity (WMH) is more strongly related to amnestic mild cognitive impairment (MCI). Infarcts are more strongly related to non-amnestic MCI. The nature of WMH in amnestic MCI requires further study.

Volumetric brain changes in females with fragile X-associated tremor/ataxia syndrome (FXTAS)

BACKGROUND

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder occurring in male and rare female carriers of a premutation expansion (55 to 200 CGG repeats) of the fragile X mental retardation 1 (FMR1) gene.

METHODS

Volumetric MRI studies, clinical staging, cognitive testing, and molecular analysis were conducted in 15 female premutation carriers affected by FXTAS (age 59.5 +/- 10.3 years), 20 unaffected female carriers (43.3 +/- 11.2 years), 11 genetically normal female controls (51.0 +/- 10.3 years), 36 affected male carriers (65.0 +/- 5.6 years), 25 unaffected male carriers (53.5 +/- 12.5 years), and 39 male controls (58.0 +/- 15.0 years). Female and male carriers with FXTAS were matched on duration of disease.

RESULTS

We found less pronounced reductions of cerebellar volume and a lower incidence of involvement (symmetric high T2 signal) of the middle cerebellar peduncles (MCP sign) in females affected by FXTAS (13%) compared with affected males (58%). We found reduced brain volumes and increased white matter disease associated with the presence of FXTAS in females compared with female controls. We also observed significant associations between reduced cerebellar volume and both increased severity of FXTAS symptoms and increased length of the CGG repeat expansion in male premutation carriers, but not in females.

CONCLUSIONS

Females affected by fragile X-associated tremor/ataxia syndrome (FXTAS) demonstrated milder brain changes than affected males, although they showed a similar pattern of radiologic findings consistent with brain atrophy and white matter disease. FXTAS should be considered (by ordering fragile X DNA testing) in females who present with late-onset ataxia, action tremor, or neuropathy, particularly in those with a family history of mental retardation, autism, or premature ovarian failure.

Inflammatory biomarkers are associated with total brain volume: the Framingham Heart Study

BACKGROUND

Systemic inflammation is associated with ischemia and Alzheimer disease (AD). We hypothesized that inflammatory biomarkers would be associated with neuroimaging markers of ischemia (i.e., white matter hyperintensities [WMH]) and AD (i.e., total brain volume [TCB]).

METHODS

MRI WMH and TCB were quantified on 1,926 Framingham Offspring participants free from clinical stroke, TIA, or dementia (mean age 60 +/- 9 years; range 35 to 85 years; 54% women) who underwent measurement of a circulating inflammatory marker panel, including CD40 ligand, C-reactive protein, interleukin-6 (IL-6), soluble intracellular adhesion molecule-1, monocyte chemoattractant protein-1, myeloperoxidase, osteoprotegerin (OPG), P-selectin, tumor necrosis factor-alpha (TNFalpha), and tumor necrosis factor receptor II. To account for head size, both TCB (TCBV) and WMH (WMH/TCV) were divided by total cranial volume. We used multivariable linear regression to relate 10 log-transformed inflammatory biomarkers to brain MRI measures.

RESULTS

In multivariable models, inflammatory markers as a group were associated with TCBV (p < 0.0001) but not WMH/TCV (p = 0.28). In stepwise models adjusted for clinical covariates with backwards elimination of markers, IL-6 and OPG were inversely associated with TCBV; TNFalpha was inversely related to TCBV in a subset of 1,430 participants. Findings were similar in analyses excluding individuals with prevalent cardiovascular disease. The relations between TCBV and inflammatory markers were modified by both sex and age, and generally were more pronounced in men and in older individuals.

CONCLUSIONS

Although our observational cross-sectional data cannot establish causality, they are consistent with the hypothesis that higher inflammatory markers are associated with greater atrophy than expected for age.

Molecular and imaging correlates of the fragile X-associated tremor/ataxia syndrome

OBJECTIVES

To assess changes in regional brain volumes associated with the fragile X-associated tremor/ataxia syndrome (FXTAS) and the molecular correlates of these changes.

METHODS

We administered molecular, MRI, and neurocognitive tests to 36 male premutation carriers (ages 51 to 79), 25 affected and 11 unaffected with FXTAS, and to 21 control subjects of similar age and education.

RESULTS

We found differences among the three groups in whole brain, cerebrum, cerebellum, ventricular volume, and whole-brain white matter hyperintensity, with the affected group showing significantly more pathology than the control and unaffected groups. Brainstem volume was significantly smaller in the unaffected group vs controls but did not differ from the affected group. Within the premutation sample, CGG repeat length correlated with reductions in IQ and cerebellar volume and increased ventricular volume and whole-brain white matter hyperintensity.

CONCLUSIONS

The current findings, coupled with recent evidence linking the degree of neuropathology (numbers of intranuclear inclusions) to the size of the premutation allele, provide evidence that the neurodegenerative phenotype in the fragile X-associated tremor/ataxia syndrome is a consequence of the CGG repeat expansion.

Longitudinal volumetric MRI change and rate of cognitive decline

OBJECTIVE

To examine how baseline and change of volumetric MRI relate to cognitive decline in older individuals.

BACKGROUND

Memory is associated with hippocampal integrity, whereas executive function has been linked to impaired frontal lobe function. Previous studies have shown that hippocampal and cortical atrophy are more strongly related to cognition than are measures of subcortical cerebrovascular disease (CVD). The authors hypothesized that memory (MEM) decline would be related to change in hippocampal volume (HC), whereas decline in executive function (EXEC) would be related to change of cortical gray matter volume (CGM) and measures of subcortical CVD.

METHODS

Subjects from a multicenter study (n = 103) included cognitively normal, mildly impaired, and demented cases with and without subcortical lacunes. All had longitudinal cognitive evaluation (mean = 4.8 years) and two or more MRI scans at least one year apart (mean = 3.4 years). MRI measures included HC, CGM, total lacune volume (LAC), and white matter hyperintensity volume (WMH). Random effects modeling of longitudinal data assessed effects of MRI baseline and MRI change on baseline and change of psychometrically matched measures of MEM and EXEC.

RESULTS

Change in MEM was related to HC baseline and HC change. Change in EXEC was related to baseline CGM and to change in CGM, HC, and LAC. Results were unchanged when demented cases were excluded. WMH was not associated with change in MEM or EXEC independent of HC, CGM, and LAC.

CONCLUSION

Hippocampal volume was the primary determinant of memory decline, whereas executive function (EXEC) decline was related to multiple brain components. Results support a hypothesis that MEM decline is strongly influenced by Alzheimer disease (AD), whereas EXEC decline may be complexly determined by cerebrovascular disease and AD.

Rate of progression differs in frontotemporal dementia and Alzheimer disease

OBJECTIVE

To compare survival and rates of cognitive and functional decline in patients with autopsy-confirmed frontotemporal dementia (FTD) and Alzheimer disease (AD) in a large multicenter study.

BACKGROUND

Despite advances in the clinical characterization of FTD, little is known about its rate of progression. Characterizing survival and rate of decline in FTD is important because it can provide prognostic guidelines and benchmarks to use in the evaluation of disease-modifying drugs.

METHODS

Seventy patients with FTD and 70 patients with AD who were followed by seven Alzheimer disease research centers until confirmation of diagnosis at autopsy were matched for overall age, education, and Mini-Mental State Examination (MMSE) score at initial evaluation. Survival and rates of cognitive and functional decline were compared.

RESULTS

Patients with FTD had significantly shorter survival from initial evaluation to death than patients with AD (FTD = 4.2 years, AD = 6.0 years; log-rank test = 5.17, p < 0.05), and they declined significantly faster over one year on the MMSE (mean annual rate of change: -6.7 points for FTD vs -2.3 points for AD). A significantly greater proportion of patients with FTD were impaired in basic activities of daily living (ADLs) at initial evaluation, and lost the capacity for independent or minimally-assisted ADLs over the subsequent year.

CONCLUSIONS

The results are consistent with shorter survival and faster rates of cognitive and functional decline in patients with frontotemporal dementia (FTD) compared to those with Alzheimer disease (AD). This suggests that FTD follows a more malignant disease course than AD once dementia is clinically recognized.

Association of sex steroid hormones with brain morphology and cognition in healthy elderly men

BACKGROUND

There is inconsistent evidence of the presence and direction of the relationship between sex hormone concentrations and cognitive function in older men, and there is little published literature on the relationship of sex hormone concentrations and brain volume as measured by MRI.

OBJECTIVE

To examine the hypothesis that midlife total serum concentrations of testosterone (T), estradiol, estrone, and sex hormone binding globulin (SHBG) predict cognitive task performance and regional brain volumes at 10- to 16-year follow-up, in a longitudinal sample of World War II veteran twin men.

METHODS

Treating twins as individuals, linear regression models were used, adjusting analyses for age, education, depressive symptomatology, blood pressure, alcohol consumption, years of cigarette smoking, and APOE epsilon4 allele status.

RESULTS

There were no significant associations between sex hormone or SHBG concentrations and performance on a series of cognitive tasks measuring global and executive function, visual and verbal learning and memory. Higher midlife T concentrations were associated with larger hemispheric, frontal, and parietal regional brain volumes and with smaller left occipital brain volume. Higher estradiol and estrone concentrations were also associated with smaller right (estradiol) and both right and left (estrone) occipital volumes, but with no other brain regions. Owing to the multiple comparisons conducted, some significant associations may have occurred by chance.

CONCLUSIONS

Overall, the pattern of results suggests a role for sex hormones in brain volume that predates potentially observable associations between sex hormones and cognitive task performance.

Stroke risk profile, brain volume, and cognitive function: the Framingham Offspring Study

BACKGROUND

Mid-life stroke risk factors have been related to late-life cognitive impairment. This association may result not only from clinical strokes but also from subclinical brain injury, such as a global atrophy demonstrable on quantitative brain MRI.

METHODS

The authors evaluated the community-based cohort of Framingham Offspring Study participants. A total of 1,841 subjects (mean age, 62 years; 857 men, 984 women) who underwent quantitative MRI and cognitive testing between 1999 and 2001 and were free of clinical stroke and dementia constituted our study sample. The authors used age- and sex-adjusted linear regression models to relate previous (1991 to 1995) and recent (1998 to 2001) Framingham Stroke Risk Profile (FSRP) scores to the total cerebral brain volume ratio (TCBVr) on follow-up MRI, and further to relate the TCBVr with education-adjusted scores on neuropsychological tests administered at the time of imaging.

RESULTS

There was an inverse association between FSRP scores and TCBVr. The TCBVr also showed a significant positive association with performance on tests of attention (Trails A), executive function (Trails B), and visuospatial function (visual reproduction, Hooper visual organization), but not with performance on tests of verbal memory or naming.

CONCLUSIONS

The Framingham Stroke Risk Profile may identify subjects with smaller brains and poorer cognitive function among stroke- and dementia-free subjects, reinforcing the importance of managing stroke risk factors.

Memory impairment, but not cerebrovascular disease, predicts progression of MCI to dementia

BACKGROUND

Mild cognitive impairment (MCI) is widely viewed as the transition phase between normal aging and Alzheimer disease (AD). Given that MCI can also result from cerebrovascular disease (CVD), the authors used clinical, MRI, and cognitive measures of AD and CVD to test the hypothesis that CVD increases the likelihood of progression from MCI to dementia within 3 years.

OBJECTIVE

To examine the impact of CVD on progression of MCI to dementia.

METHODS

Fifty-two consecutive patients with MCI (71% men) including many with symptomatic CVD were longitudinally evaluated for 3.1 +/- 1.3 years. MCI was defined as a Clinical Dementia Rating Scale (CDR) score of 0.5. Dementia was defined as progression to a CDR score of > or =1.0.

RESULTS

Forty-four percent of the MCI patients had MRI infarcts, 50% of which were symptomatic. Thirty-three percent of patients progressed to dementia, and 37.8% of these had MRI infarcts. Clinically probable or possible AD was diagnosed in approximately 82% of converters. Of the clinical and MRI measures, only hippocampal volume was associated with increased risk to progression (hazard ratio [HR] = 0.31 [95% CI 0.1 to 0.92], p = 0.03). When neuropsychological measures were included in the analysis, memory (HR = 0.90 [95% CI 0.84 to 0.96], p = 0.002) and executive function (HR = 0.96 [95% CI 0.92 to 1.0], p = 0.045) were associated with increased risk of dementia progression, whereas APOE genotype, cerebrovascular risk factors, clinical stroke, presence or absence of lacunes, and extent of white matter hyperintensities did not predict progression.

CONCLUSION

Within a heterogenous group of MCI patients, including many with clinically significant CVD, baseline memory and executive performance significantly predicted likelihood to develop dementia.

White matter lesions impair frontal lobe function regardless of their location

OBJECTIVE

To analyze the effect of white matter lesions in different brain regions on regional cortical glucose metabolism, regional cortical atrophy, and cognitive function in a sample with a broad range of cerebrovascular disease and cognitive function.

METHODS

Subjects (n = 78) were recruited for a study of subcortical ischemic vascular disease (SIVD) and Alzheimer disease (AD) contributions to dementia. A new method was developed to define volumes of interest from high-resolution three-dimensional T1-weighted MR images. Volumetric measures of MRI segmented white matter signal hyperintensities (WMH) in five different brain regions were related to regional PET glucose metabolism (rCMRglc) in cerebral cortex, MRI measures of regional cortical atrophy, and neuropsychological assessment of executive and memory function.

RESULTS

WMH was significantly higher in the prefrontal region compared to the other brain regions. In all subjects, higher frontal and parietal WMH were associated with reduced frontal rCMRglc, whereas occipitotemporal WMH was only marginally associated with frontal rCMRglc. These associations were stronger and more widely distributed in nondemented subjects where reduced frontal rCMRglc was correlated with WMH for all regions measured. In contrast, there was no relationship between WMH in any brain region and rCMRglc in either parietal or occipitotemporal regions. WMHs in all brain regions were associated with low executive scores in nondemented subjects.

CONCLUSIONS

The frontal lobes are most severely affected by SIVD. WMHs are more abundant in the frontal region. Regardless of where in the brain these WMHs are located, they are associated with frontal hypometabolism and executive dysfunction.

Mild cognitive impairment--beyond controversies, towards a consensus: report of the International Working Group on Mild Cognitive Impairment

The First Key Symposium was held in Stockholm, Sweden, 2-5 September 2003. The aim of the symposium was to integrate clinical and epidemiological perspectives on the topic of Mild Cognitive Impairment (MCI). A multidisciplinary, international group of experts discussed the current status and future directions of MCI, with regard to clinical presentation, cognitive and functional assessment, and the role of neuroimaging, biomarkers and genetics. Agreement on new perspectives, as well as recommendations for management and future research were discussed by the international working group. The specific recommendations for the general MCI criteria include the following: (i) the person is neither normal nor demented; (ii) there is evidence of cognitive deterioration shown by either objectively measured decline over time and/or subjective report of decline by self and/or informant in conjunction with objective cognitive deficits; and (iii) activities of daily living are preserved and complex instrumental functions are either intact or minimally impaired.

Mild cognitive impairment--beyond controversies, towards a consensus: report of the International Working Group on Mild Cognitive Impairment

The First Key Symposium was held in Stockholm, Sweden, 2-5 September 2003. The aim of the symposium was to integrate clinical and epidemiological perspectives on the topic of Mild Cognitive Impairment (MCI). A multidisciplinary, international group of experts discussed the current status and future directions of MCI, with regard to clinical presentation, cognitive and functional assessment, and the role of neuroimaging, biomarkers and genetics. Agreement on new perspectives, as well as recommendations for management and future research were discussed by the international working group. The specific recommendations for the general MCI criteria include the following: (i) the person is neither normal nor demented; (ii) there is evidence of cognitive deterioration shown by either objectively measured decline over time and/or subjective report of decline by self and/or informant in conjunction with objective cognitive deficits; and (iii) activities of daily living are preserved and complex instrumental functions are either intact or minimally impaired.

Volumetric MRI predicts rate of cognitive decline related to AD and cerebrovascular disease

OBJECTIVE

To examine volumetric MRI correlates of longitudinal cognitive decline in normal aging, AD, and subcortical cerebrovascular brain injury (SCVBI).

BACKGROUND

Previous cross-sectional studies examining the relationship between cognitive impairment and dementia have shown that hippocampal and cortical gray matter atrophy are the most important predictors of cognitive impairment, even in cases with SCVBI. The authors hypothesized that hippocampal and cortical gray matter volume also would best predict rate of cognitive decline in cases with and without SCVBI.

METHODS

Subjects were recruited for a multicenter study of contributions to dementia of AD and SCVBI. The sample (n = 120) included cognitively normal, cognitively impaired, and demented cases with and without lacunes identified by MRI. Cases with cortical strokes were excluded. Average length of follow-up was 3.0 years. Measures of hippocampal volume, volume of cortical gray matter, presence of subcortical lacunes, and volume of white matter hyperintensity were derived from MRI. Random effects modeling of longitudinal data was used to assess effects of baseline MRI variables on longitudinal change in a measure of global cognitive ability.

RESULTS

Cortical gray matter atrophy predicted cognitive decline regardless of whether lacunes were present. Hippocampal atrophy predicted decline only in those without lacunes. Neither lacunes nor white matter hyperintensity independently predicted decline.

CONCLUSIONS

Results suggest that cortical atrophy is an index of disease severity in both AD and subcortical cerebrovascular brain injury and consequently predicts faster progression. Hippocampal volume may index disease severity and predict progression in AD. The absence of this effect in cases with lacunes suggests that this group is etiologically heterogeneous and is not composed simply of cases of AD with incidental stroke.

The role of neuroimaging in dementia

Potential new therapies for the treatment of Alzheimer's disease demand early and accurate diagnosis. Although clinical evaluation is generally sufficient when the disease is well established, neuroimaging tools are helpful to detect the earliest changes of Alzheimer's disease or differentiate Alzheimer's disease from the other forms of dementia. This article reviews the basic concepts of brain imaging and clinical application. It concludes with a brief discussion of future directions in neuroimaging for the diagnosis and longitudinal follow-up of Alzheimer's disease.

Cerebrovascular and brain morphologic correlates of mild cognitive impairment in the National Heart, Lung, and Blood Institute Twin Study

OBJECTIVE

To evaluate the relative risk (RR) of mild cognitive impairment (MCI) associated with cerebrovascular risk factors and cerebrovascular-related brain changes.

DESIGN

Mild cognitive impairment was determined for the subjects of the prospective National Heart, Lung, and Blood Institute Twin Study. Quantitative measures of brain, white matter hyperintensity, cerebral infarction, apolipoprotein E genotype, and psychometric testing were obtained.

RESULTS

Subjects with MCI were older (73.5 +/- 3.0 vs 72.1 +/- 2.8 years), consumed less alcohol (3.7 +/- 5.8 vs 7.0 +/- 10.7 drinks per week), had greater white matter hyperintensity volumes (0.56% +/- 0.82% vs 0.25% +/- 0.34% of cranial volume), and had an increased prevalence of apolipoprotein E4 genotype (31.4% vs 19.2%) than normal subjects. White matter hyperintensity and the presence of the apolipoprotein E4 genotype were associated with a significantly increased risk for MCI. When all subjects were included in the analysis, alcohol consumption was associated with a reduced risk for MCI (RR = 0.93, P<.05). When subjects with a history of symptomatic cerebrovascular disease were excluded from the analysis, elevated midlife diastolic blood pressure was associated with an increased risk for MCI (RR = 1.70, P<.05).

CONCLUSIONS

Elevated midlife blood pressures, and the resulting increased white matter hyperintensities, increase the risk for MCI in a group of community-dwelling older men to at least the same degree as apolipoprotein E4 genotype. Given the common occurrence of elevations in midlife blood pressure, early and effective treatment may be warranted to prevent late-life brain abnormalities and MCI. Moreover, since many individuals with MCI progress to clinical dementia, longitudinal evaluations of this cohort will be important.

Postoperative changes in cerebral metabolism in temporal lobe epilepsy

BACKGROUND

Fludeoxyglucose F 18 positron emission tomography ((18)F-FDG-PET) can detect focal metabolic abnormalities ipsilateral to the seizure focus in 80% of patients with temporal lobe epilepsy (TLE). Regions outside the epileptogenic zone can also be affected. We hypothesized that these remote regions might show altered metabolism, tending to return toward normal values, after surgery.

DESIGN

Interictal preoperative and postoperative (18)F-FDG-PET metabolism were compared in patients with refractory TLE. Based on pathological findings, disease was classified in the following 3 groups: mesial temporal sclerosis, mass lesions, and no pathological diagnosis. Quantitative PET data analysis was performed using the region-of-interest template previously described. Global normalization was used to adjust for the effect of antiepileptic medication changes. Data were analyzed by Wilcoxon signed rank test and analysis of variance.

SETTING

The Clinical Epilepsy Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health.

PATIENTS

Twenty-two patients with refractory TLE.

RESULTS

Preoperatively, in all groups, cerebral metabolic rate for glucose was decreased ipsilateral to the resection site in inferior lateral temporal, inferior mesial temporal, and inferior frontal areas and thalamus. Postoperatively, in all groups, cerebral metabolic rate for glucose increased in ipsilateral inferior frontal area and thalamus. In the mesial temporal sclerosis group, we found a statistically significant increase in the contralateral thalamus.

CONCLUSION

Temporal lobe epilepsy is associated with extensive preoperative decreased metabolism in inferior lateral temporal, inferior mesial temporal, and inferior frontal areas and thalamus. Postoperatively, we found increased IF and thalamic metabolism. Seizures may have a reversible effect on brain areas connected with, but remote from, the epileptogenic cortex. Arch Neurol. 2000;57:1447-1452

Cerebrospinal fluid viral load is related to cortical atrophy and not to intracerebral calcifications in children with symptomatic HIV disease

The relationships between viral load in plasma and cerebrospinal fluid (CSF) and computed tomography (CT) brain scan abnormalities were studied in 39 children between 0.5 and 13 years of age with symptomatic HIV-1 disease. Quantitative RNA PCR was used to determine HIV-1 RNA levels and a semiquantitative analog rating technique was used to evaluate non-contrast CT brain scans. CSF HIV-1 RNA copy number correlated significantly with CT brain scan ratings for severity of cortical atrophy (r = 0.36; P < 0.05) but not with ratings of intracerebral calcifications (r = -12; NS). The difference between these two correlations was significant (P < 0.05). Plasma HIV-1 RNA copy number did not correlate significantly with any CT brain scan ratings or with CSF viral load (r = 0.05; NS). Severity of cortical atrophy appeared to reflect the level of viral load in the CSF, supporting the notion that active HIV-1 replication in the CNS is at least in part responsible for such brain abnormalities in children. The lack of correlation of intracerebral calcifications with other CT brain scan abnormalities as well as with CSF viral load suggests that this lesion is relatively independent and may reflect a different neuropathologic process.

Relationship of seizure frequency to hippocampus volume and metabolism in temporal lobe epilepsy

PURPOSE

To examine the relationship between frequency of complex partial (CPS) and secondarily generalized tonic-clonic seizures (sGTCS) on hippocampal volume (HV) and temporal lobe metabolism.

METHODS

We performed volumetric magnetic resonance imaging (MRI) and positron emission tomography with 18fluorodeoxyglucose (18FDG-PET) in 32 patients with epilepsy. Temporal lobe foci were localized by ictal video-EEG.

RESULTS

We did not find any association between CPS frequency or lifetime number of sGTCS and HV or metabolism ipsilateral to electroencephalographic focus.

CONCLUSION

The progress of metabolic or pathologic abnormalities of temporal lobe epilepsy may not be altered by adequate seizure control. The presence of an epileptic focus might be associated with progressive neuronal injury even in clinically well-controlled patients.

NAD(P)H:quinone oxidoreductase activity is increased in hippocampal pyramidal neurons of patients with Aalzheimer's disease

NAD(P)H:quinone oxidoreductase (QR) catalyzes the two-electron reduction of quinones, preventing their participation in redox cycling and subsequent generation of reactive oxygen species. Pretreatment of neuroblastoma cells with compounds, such as tert-butylhydroquinone and dimethyl fumarate, that increase QR expression protect cells from oxidative stress-induced cell death by glutamate, H(2)O(2,) and dopamine. The potential neuroprotective role of QR as well as the evidence for oxidative stress-induced neuronal cell death in Alzheimer's disease (AD) led us to examine the expression pattern of QR from AD and control patients. Histochemical staining of hippocampal sections from AD patients revealed QR activity in pyramidal neurons. The presence of QR protein in these neurons also was confirmed by immunoreactivity. In control patients, hippocampal pyramidal neurons were negative for both QR enzymatic activity and QR immunoreactivity. In addition, the QR positive neurons of AD patients were selectively located in areas where neuronal populations exhibited tau immunostaining. Our data demonstrate that QR is up-regulated in hippocampal pyramidal neurons of AD patients. We hypothesize that this is part of a neuroprotective system up-regulated in response to the AD process. Understanding this system may lead to further insights into the pathogenesis and potential new avenues of treatment for AD.

Biobehavioral characteristics of nondemented older adults with subclinical brain atrophy

OBJECTIVE

To characterize the risk factors and neuropsychological performance of two subgroups of community-dwelling, white elderly men free of severe cognitive impairment (n = 383; mean age, 72.9 +/- 3.0 years) who differ on volumetric measurements of total brain parenchyma and white matter hyperintensity (WMH) volumes.

METHODS

Group comparisons were made of cerebrovascular disease risk factors measured at the time of imaging and at three prior examinations extending over 25 years of adult life. Measures of verbal memory and speed psychomotor processing at the time of imaging and 10 years before imaging were also available.

RESULTS

Compared with those in the "nonatrophy" group, individuals in the subgroup with "atrophy" (defined by low total brain volume and high WMH volume) were older, reported a higher level of depressive symptomatology, experienced a steeper decline in diastolic blood pressure (DBP) and a steeper increase in pulse pressure, were less physically active, had smoked for more years, and had a higher prevalence of several cardiovascular disease indicators, including an ankle/arm systolic blood pressure ratio less than 0.9, and hypertension. After multivariate analysis, the 25-year decline in DBP, the number of years smoked, and an ankle/arm index of less than 0.9 remained significant discriminators of the two groups. Lower levels of speeded performance at the time of imaging and a steeper 10-year decline in cognitive performance on selected tests were also observed in the atrophic group.

CONCLUSION

Community-dwelling older adults with volumetric brain measurements associated with accelerated aging are distinguishable on the basis of several health-related characteristics. These individuals also perform less well on certain tasks involving executive functioning.

Head injury and the risk of AD in the MIRAGE study

OBJECTIVES

It has been suggested in some studies that head injury is a risk factor for AD, and that this risk is heightened among carriers of the APOE-epsilon4 allele. We examined the effects of head injury and APOE genotype on AD risk in a large family study.

SUBJECTS

A total of 2,233 probands who met criteria for probable or definite AD and their 14,668 first-degree family members (4,465 parents, 7,694 siblings, and 2,509 spouses) were ascertained at 13 centers in the United States, Canada, and Germany participating in the MIRAGE (Multi-Institutional Research in Alzheimer Genetic Epidemiology) project. Information on head injury was collected by interview of multiple informants and review of medical records. Nondemented relatives and spouses served as control subjects for this study.

METHODS

Odds of AD for head trauma with or without loss of consciousness were computed by comparing probands with unaffected spouses using conditional logistic regression analysis. To account for the unique biologic relationship between probands and their parents and siblings, odds of AD were computed using a generalized estimating equation (GEE) Poisson regression approach. GEE logistic regression was used to examine the joint effects of APOE genotype and head injury on the odds of AD in probands and a control group comprised of unaffected siblings and spouses.

RESULTS

Comparison of probands with their unaffected spouses yielded odds ratios for AD of 9.9 (95% CI, 6.5 to 15.1) for head injury with loss of consciousness and 3.1 (2.3 to 4.0) for head injury without loss of consciousness. The corresponding odds derived from the comparison of probands with their parents and sibs were 4.0 (2.9 to 5.5) for head injury with loss of consciousness and 2.0 (1.5 to 2.7) for head injury without loss of consciousness. Head injury without loss of consciousness did not significantly increase the risk of AD in spouses (OR = 1.3; 95% CI, 0.4 to 4.1). The joint effects of head injury and APOE genotype were evaluated in a subsample of 942 probands and 327 controls (spouses and siblings). Head injury increased the odds of AD to a greater extent among those lacking epsilon4 (OR = 3.3) than among epsilon4 heterozygotes (OR = 1.8) or homozygotes (OR = 1.3).

CONCLUSION

Head injury is a risk factor for AD. The magnitude of the risk is proportional to severity and heightened among first-degree relatives of AD patients. The influence of head injury on the risk of AD appears to be greater among persons lacking APOE-epsilon4 compared with those having one or two epsilon4 alleles, suggesting that these risk factors may have a common biologic underpinning.

Relationship of family history scores for stroke and hypertension to quantitative measures of white-matter hyperintensities and stroke volume in elderly males

White-matter hyperintensities (WMHI) are frequently associated with cerebrovascular risk factors in the elderly, particularly hypertension, and have been interpreted as a subclinical form of ischemic brain damage. WMHI, clinical stroke and blood pressures show significant genetic influences. The objective of this study was to determine whether a relationship exists between family history of stroke and/or hypertension in first degree relatives and WMHI in the elderly. WMHI and stroke (CVA) volumes were quantified from brain MRI performed on 414 white, male twins born between 1917 and 1927 (average age 72.3 +/- 2.9 years). WMHI, adjusted for age and head size, was significantly correlated with the family history score (r = 0.21, p < 0.001). Dividing the family history scores into quintiles revealed significant differences in WMHI by quintile mean (p < 0.05). Subjects in the highest quintile of family history score had the highest mean WMHI. Recalculation of the family history score, by only counting relatives reported to have had a clinical stroke as a positive event, revealed a nonsignificant correlation with WMHI, but the correlation of the family history score with MRI CVA volume was significant (p < 0.05). Stepwise multivariate analysis including ApoE status, current smoking status, smoking packyear history, Doppler ankle/arm blood pressure ratios, current and long term hypertensive status and current systolic and diastolic pressures indicated that the stroke/hypertension family history score was the single best predictor (p < 0.01) of WMHI volumes. Family history was not an independent predictor of CVA volume.

The joint effect of apolipoprotein E epsilon4 and MRI findings on lower-extremity function and decline in cognitive function

BACKGROUND

Cognitive decline and poor physical function are risk factors for disability in old age and may occur more often in subjects with the apolipoprotein E epsilon4 (ApoE-epsilon4) allele. The objective of this study was to investigate the joint effect of ApoE-epsilon4 and structural changes detected on MRI brain scans on cognitive decline and lower-extremity function.

METHODS

Brain MRI (1.5 T), neuropsychological tests, and lower-extremity physical function tests were administered to World War II male veteran twins ages 69 to 80. Quantification of MRI scans used a previously published algorithm to segment brain images into total cerebral brain (TCB), cerebrospinal fluid (CSF), and white-matter hyperintensity (WMH) volumes. A short battery of physical performance tests was used to assess lower-extremity function. Ten-year changes in performance on the Mini-Mental State Exam (MMSE), the Benton Visual Retention Test (BVRT), and the Digit Symbol Substitution (DSS) test were used to assess cognitive decline.

RESULTS

For the sample as a whole, the comparison of subjects by median split of total cerebral brain volume found that those with brain volumes below the median performed worse on tests of gait and balance (p < .01) and experienced greater cognitive decline on the MMSE and BVRT cognitive test batteries (both p < .01). In addition, subjects with WMH volumes above the median had poor performance on the standing balance tasks and experienced greater decline on the DSS test (p < .01). Stratified analyses revealed that the joint effect of radiological findings and the ApoE-epsilon4 allele on cognitive decline and lower-extremity function was often greater than that expected from the separate effects combined.

CONCLUSIONS

We conclude that radiological findings in conjunction with ApoE-epsilon4 may single out a group at higher risk for dementia. We speculate that the observed interaction effect may be due to increased susceptibility to brain injury or impaired repair mechanisms in subjects with ApoE-epsilon4.

Apolipoprotein E genotype and hippocampal asymmetry in Alzheimer's disease: a volumetric MRI study

Asymmetry of brain structures is common to many species and is even present in utero. Some developmental, pathological, and dementing diseases are associated with alterations in normal anatomical asymmetries. Anatomical asymmetries, however, have been only superficially studied in Alzheimer's disease. Recent evidence indicates that the allele epsilon4 of the apolipoprotein E (ApoE), a well known risk factor for Alzheimer's disease, might play a part in determining some brain morphological changes both in normal carriers and in patients with Alzheimer's disease. This study evaluated the effect of the ApoE genotype on hippocampal asymmetry in patients with Alzheimer's disease carrying 0, 1, and 2 copies of the allele. Volumetric right-left differences of the hippocampi were computed in 28 right handed patients with Alzheimer's disease (14 -/-, 9 epsilon4/-, and 5 epsilon4/4) and 30 controls without detectable cognitive deficit. In controls, the right hippocampus was larger than the left, whereas in patients with Alzheimer's disease this asymmetry was progressively reduced with increasing gene dose of the epsilon4 allele, and the asymmetry was reversed in the epsilon4/4 Alzheimer's disease group. The mean right-left volume differences were: 1.2, 0.7, 0.2, and -1.0 in controls, -/-, epsilon4/-, and epsilon4/4 patients, respectively (sex adjusted p for trend=0.017). The data indicate a dose dependent effect of the ApoE epsilon4 allele on hippocampal volume asymmetry in Alzheimer's disease.

APOE-epsilon4 is associated with less frontal and more medial temporal lobe atrophy in AD

OBJECTIVE

To test the hypothesis that the e4 allele of APOE is associated with a region-specific pattern of brain atrophy in AD.

METHODS

Volumes of the hippocampi, entorhinal cortices, and anterior temporal and frontal lobes were measured in 28 mild to moderate AD patients and 30 controls using MRI. Within the AD group, 14 patients were noncarriers (-/-), 9 were heterozygous (e4/-), and 5 were homozygous (e4/4) for the e4 allele. Dementia severity was similar across the three AD groups.

RESULTS

Smaller volumes were found with increasing dose of the e4 allele in the hippocampus, entorhinal cortex, and anterior temporal lobes in AD patients. When compared with controls, the volume loss in the right and left temporal regions ranged from -15.3 to -22.7% in the -/- AD group, from -26.2 to -36.0% in the e4/- group, and from -24.0 to -48.0% in the e4/4 group (p < 0.0005). In contrast, larger volumes were found in the frontal lobes with increasing e4 gene dose. When compared with controls, volume differences of the right frontal lobe were -11.8% in the -/- AD group, -8.5 in the e4/- group, and -1.4% in the e4/4 group (p = 0.03).

CONCLUSIONS

We found smaller volumes in the temporal lobe regions but larger volumes in the frontal lobes with increasing APOE-e4 gene dose in AD patients. These data suggest a region-specific biological effect of the e4 allele in the brains of AD patients.

Differential genetic influence for components of memory in aging adult twins

OBJECTIVE

To investigate the relative proportion of genetic and environmental contributions to verbal memory in community-dwelling World War II veteran twins.

DESIGN

The California Verbal Learning Test (CVLT) was administered to 94 monozygotic (MZ) and 89 dizygotic (DZ) elderly male twin pair participants in the fourth examination of the National Heart, Lung, and Blood Institute Twin Study.

SETTING

Subjects voluntarily participated on an outpatient basis at a research or medical center facility in 1 of 4 sites in the United States.

PARTICIPANTS

Subjects had a mean age of 71.8 years (SD, 2.9 years), a mean educational level of 13.6 years (SD, 2.8 years), and no history of stroke and/or a Mini-Mental State Examination score of 23 or greater.

MAIN OUTCOME MEASURES

Twin pair similarity in performance on 4 factor analytically derived components of the CVLT measuring verbal learning and memory, response discrimination, learning strategy, and recognition memory.

RESULTS

The MZ intraclass correlation was significantly larger than the DZ correlation for verbal learning and memory (I<.001) but not for the other 3 components of memory. Using maximum likelihood methods, the best-fitting genetic model indicated that verbal learning and memory has a substantial genetic component (56% of total variance), whereas response discrimination has a much smaller, although still detectable, genetic component (24% of total variance). There is no evidence of genetic influence on learning strategy or recognition memory.

CONCLUSION

Differential contribution of genetic and environmental influences to specific components of memory suggest that, in this group of elderly male twin pairs, some components may be more amenable to intervention than others.

Impact of apolipoprotein E epsilon4 and vascular disease on brain morphology in men from the NHLBI twin study

BACKGROUND AND PURPOSE

Apolipoprotein E epsilon4 genotype (ApoE4) has been associated with increased risk for cardiovascular disease morbidity or mortality. This appears to be mediated by an ApoE4-related increase in cardiovascular atherosclerosis. Given the similarities between risk factors for heart disease and risk factors for stroke, a positive association between ApoE4 and stroke would be expected. Since age-related brain atrophy and the extent of white matter hyperintensities (WMH) share similar risk factors, we examined the combined effect of ApoE4 and history of vascular disease on brain volume, WMH, and MRI evidence of stroke.

METHODS

Subjects were the surviving members of the National Heart, Lung, and Blood Institute Twin Study. This is a longitudinal study of the effects of cardiovascular disease risk factors in community-dwelling male veterans. The fourth and final examination of this cohort included cerebral MRI and was completed in 1997. Apolipoprotein E (ApoE) genotype, quantitative measures of brain volume, WMH, and the presence of stroke on MRI were obtained from the 396 participants in the final examination. The presence or absence of a history of coronary heart disease, cerebrovascular disease, peripheral arterial disease, and ApoE genotype were determined for each subject.

RESULTS

Of the 396 men, 88 (22%) had at least 1 ApoE4 allele. ApoE4 was not associated with differences in age or education. While the prevalence of vascular disease was generally greater in the ApoE4 group, this was only significant for coronary heart disease (29.8% in subjects without ApoE4 versus 40.7% in subject with ApoE4; P=0.03). ApoE4 subjects had significantly smaller brain volumes (942.4+/-34.5 versus 952.2+/-40.1 cm(3); P=0. 02). MRI evidence of stroke was detected in 88 (22%) of the subjects. The distribution of ApoE genotype was marginally different between subjects with MRI-detected stroke compared with those without. Further analysis revealed that the co-occurrence of cerebrovascular disease and ApoE4 was associated with significantly greater brain atrophy and WMH than either ApoE4 or cerebrovascular disease alone. Similar relations were seen for coronary heart disease and peripheral arterial disease.

CONCLUSIONS

We conclude that ApoE4 enhances the extent of brain abnormalities in the presence of various vascular diseases. We speculate that this effect may be mediated by an increased susceptibility to brain injury or impaired repair mechanisms associated with ApoE4.

Midlife cardiovascular risk factors and brain morphology in identical older male twins

OBJECTIVE

Structural changes in the human brain have been reported to a greater extent in subjects with cardiovascular risk factors. We conducted a matched co-twin analysis of elderly monozygotic twins from the National Heart, Lung, and Blood Institute Twin Study to examine the association between midlife cardiovascular risk factors and MRI-based measures of brain atrophy.

METHODS

Brain MRIs (1.5-T) were obtained from 74 monozygotic, white, male, World War II veteran twins born in the United States from 1917 to 1927 and age 68 to 79 at the time of the brain scan. A semiautomated algorithm was used to segment brain images into total brain, CSF, and white matter hyperintensity volumes. Cardiovascular risk factors, medical history variables, and health practices were available from data collected over 25 years of adult life.

RESULTS

Independent of shared genetic or familial influences, within-pair differences in midlife glucose levels, high-density lipoprotein cholesterol, and systolic blood pressure were significantly associated with differences in white matter hyperintensities. Within-pair differences in coronary heart disease history and in current consumption of alcohol and level of physical activity were significantly associated with differences in brain parenchyma. In addition, within-pair differences in white matter hyperintensity volumes were significantly associated with differences in performance on cognitive and physical function tests and self-reports of depression symptoms.

CONCLUSION

Independent of age effects and shared genetic or familial influences, midlife cardiovascular risk factors and lifetime health practices were predictive of structural brain changes in old age.

Predictors of brain morphology for the men of the NHLBI twin study

BACKGROUND AND PURPOSE

Cross-sectional studies show that cerebrovascular risk factors are associated with increased brain atrophy, accumulation of abnormal cerebral white matter signals, and clinically silent stroke. We extend these findings by examining the relationship between midlife cerebrovascular risk factors and later-life differences in brain atrophy, amount of abnormal white matter, and stroke on MRI.

METHODS

Subjects were the 414 surviving members of the prospective National Heart, Lung, and Blood Institute Twin Study, who have been examined on 4 separate occasions, spanning the 25 years between 1969-1973 and 1995-1997. Quantitative measures of brain volume, volume of abnormal white matter signal (WMHI), and volume of stroke, when present, were obtained from those participating in the fourth examination.

RESULTS

The mean+/-SD age of the subjects was 47.2+/-3.0 years at initial examination and 72. 5+/-2.9 years at final examination. Average blood pressure (BP) levels were normal, although 32% of the subjects had received or were currently taking antihypertensive medications. As a group, 31% had symptomatic cardiovascular disease, 11% had symptomatic cerebrovascular disease, and 8% had symptomatic peripheral vascular disease. Both systolic and diastolic BP levels at initial examination were inversely related to brain volume and positively related to WMHI volume. Multiple regression analysis identified BP-related measures and vascular risk factors as significant predictors of brain and WMHI volumes. In addition, the magnitude of orthostatic BP change was significantly associated with WMHI volume. Subjects with extensive amounts of WMHI had significantly higher systolic BP at the final examination and a higher prevalence of symptomatic cardiovascular and cerebrovascular disease, without significant differences in the prevalence of hypertension treatment.

CONCLUSIONS

Midlife BP measures are significantly associated with later-life brain and WMHI volumes and the prevalence of symptomatic vascular disease. Since WMHI share cerebrovascular risk factors and extensive WMHI are associated with symptomatic vascular disease, extensive WMHI may be a subclinical expression of cerebrovascular disease. Careful treatment of midlife BP elevations may diminish these later-life brain changes.

Hippocampal atrophy, epilepsy duration, and febrile seizures in patients with partial seizures

BACKGROUND

Previous studies have suggested a variety of factors that may be associated with the presence of hippocampal formation (HF) atrophy in patients with complex partial seizures (CPS), including a history of complex or prolonged febrile seizures (FS), age at seizure onset, and epilepsy duration.

OBJECTIVE

To determine whether epilepsy duration is related to HF atrophy.

METHODS

We performed MRIs on 35 patients with uncontrolled CPS who had temporal lobe ictal onset on video-EEG. None had evidence for an alien tissue lesion or extra-hippocampal seizure onset. All had a history of secondary generalization. Brain structures were drawn on consecutive images and pixel points summed from successive pictures to calculate volumes.

RESULTS

Nine patients with a history of complex or prolonged FS had smaller ipsilateral HF volume and ipsilateral/contralateral ratio than did patients without a history of FS. Epilepsy duration had a significant relation to ipsilateral HF volume and ipsilateral/contralateral ratio. In a multivariate analysis, the effect of duration, but not age at onset or scan, was significant. Patients with a history of FS did not have earlier age at epilepsy onset or longer duration.

CONCLUSIONS

A history of FS predicted the severity of HF atrophy in our patients. Age at onset or study was not a significant factor. Epilepsy duration, however, did have a significant effect, suggesting that, after an initial insult, progressive HF damage may occur in patients with persistent seizures.

Association of midlife blood pressure to late-life cognitive decline and brain morphology

OBJECTIVE

To investigate the association between midlife systolic blood pressure (SBP) and late-life cognitive decline and brain morphology in a sample of community-dwelling elderly men 68 to 79 years of age.

METHODS

Subjects are surviving members from the prospective National Heart, Lung, and Blood Institute Twin Study (intake, 1969 to 1972) who, when examined for a fourth time in 1995 through 1997, underwent brain MRI and repeated assessment of neurobehavioral functioning. Quantification of the MR images determined cerebral volume and total volume of white matter hyperintensities (WMHIs) for 392 subjects. Midlife SBP levels measured in 1970, 1980, and 1985 were used to classify subjects into low, medium, and high midlife SBP categories. A 10-year change in performance on the Mini-Mental State Examination, Digit Symbol Substitution Test, Benton Visual Retention Test, and Verbal Fluency Test was also calculated for these subjects. For all reported analyses, patients were treated as genetically unrelated individuals.

RESULTS

Subjects with high midlife SBP experienced a greater decline in cognitive performance and had larger WMHI volumes at follow-up in late life than did those with low midlife SBP. Decreased brain parenchyma and increased WMHI volumes were associated with decline in neurobehavioral functioning as measured in late life independent of age, education, and baseline levels of cognition.

CONCLUSIONS

Midlife SBP is a significant predictor of both decline in cognitive function and MR volumetric measures of brain atrophy in late life. Because decline in neurobehavioral functioning was associated with decreased brain volume and increased WMHI volume, we conclude that the long-term impact of elevated SBP on decline in late-life neurobehavioral functioning is likely to be mediated through its chronic, negative effect on structural characteristics of the brain.

Evidence for genetic variance in white matter hyperintensity volume in normal elderly male twins

BACKGROUND AND PURPOSE

White matter hyperintensities (WMHs), as detected by MRI, are common among the elderly and are frequently interpreted as representing a subclinical form of ischemic brain damage. We used volumetric MR techniques to investigate the contribution of genes and the environment to measures of brain morphology in a sample of community dwelling elderly male twins.

METHODS

Brain MR (1.5 T) scans were obtained from 74 monozygotic (MZ) and 71 dizygotic (DZ), white, male, World War II veteran twins born in the United States and age 68 to 79 when scanned. MR quantification used a previously published semiautomated segmentation algorithm to segment brain images into total brain, cerebrospinal fluid (CSF), and WMH volumes. Twin pair covariances were computed for each measure, and structural equation genetic models were fitted to these data.

RESULTS

Total cranial, brain parenchyma, CSF, and WMH volumes were highly correlated in MZ pairs, and correlations in MZ pairs were significantly greater than those in DZ pairs. Structural equation modeling indicated heritabilities of 91%, 92%, and 73%, respectively, for total cranial, brain parenchyma, and WMH volumes. Correction for age and head size reduced the heritability of brain parenchyma to 62% (95% confidence interval, 56% to 68%) and the heritability of WMH volume to 71% (95% confidence interval, 66% to 76%). Proband concordance rates for large amounts of WMH were 61% in MZ pairs and 38% in DZ pairs, compared with a prevalence of 15% in the entire sample.

CONCLUSIONS

This study is the first to quantify the relative contribution of genetic and individual environmental influences to measures of brain morphology in the elderly.