MRI and genetic correlates of cognitive function in elders with memory impairment

Risk factors for hippocampal cavities in a marginally housed population

Cavities in the hippocampus are morphological variants of uncertain significance. Aberrant neurodevelopment along with vascular and inflammatory etiologies have been proposed. We sought to characterize these cavities and their potential risk factors in a marginally housed population, with high rates of viral infection, addiction, and mental illness. (1) The volume of hippocampal cavities (HCavs) is greater in this highly multimorbid population compared to the general population. (2) Conventional vascular risk factors such as greater age and systolic blood pressure are associated with higher HCav volume. (3) Nonprescribed substance-related risk factors such as stimulant use or dependence, and smoking are associated with increased HCav volume independent of vascular risk factors. This is a retrospective analysis of an ongoing prospective study. We analyzed baseline data, including medical history, physical exam, psychiatric diagnosis, and MRI from a total of 375 participants. Hippocampal cavities were defined as spaces isointense to CSF on T1 MRI sequences, bounded on all sides by hippocampal tissue, with a volume of at least 1 mm³ . Risk factors were evaluated using negative binomial multiple regression. Stimulant use was reported by 87.3% of participants, with stimulant dependence diagnosed in 83.3% of participants. Prevalence of cavities was 71.6%, with a mean total bilateral HCav volume of 13.89 mm³ . On average, a 1 mmHg greater systolic blood pressure was associated with a 2.17% greater total HCav volume (95% CI = [0.57%, 3.79%], p = .0076), while each cigarette smoked per day trended toward a 2.69% greater total HCav volume (95% CI = [-0.87%, 5.54%], p = .058). A diagnosis of stimulant dependence was associated with a 95.6% greater total HCav volume (95% CI = [5.39%, 263.19%], p = .0335). Hypertension and diagnosis of stimulant dependence were associated with a greater total volume of HCav.

Hippocampal Sulcus Remnant: Common Finding in Nonelderly Adults on Ultra-High-Resolution 7T Magnetic Resonance Imaging

OBJECTIVE

The objective of this study was to investigate the frequency of hippocampal sulcus remnants (HSRs) in nonelderly adults using ultra-high-resolution 7T magnetic resonance (MR) images and their imaging features.

METHODS

A total of 33 healthy adults underwent 7T MR, and multiplanar images of 66 temporal lobes were reviewed independently by 2 neuroradiologists. The detectability of the HSR was calculated. In addition, the interobserver agreement on the rating scale was evaluated using the κ statistic.

RESULTS

Both observers identified HSRs with 7T MR images in all subjects. Excellent interobserver agreement was shown (κ = 1.0). The shape of HSRs was variable (spot-like, curvilinear, ovoid, or beaded appearance). Volumes of the HSRs were not correlated with age.

CONCLUSIONS

Hippocampal sulcus remnants are commonly seen in healthy nonelderly adults using 7T MR imaging. Accurate diagnosis of HSR based on the microanatomy of hippocampus makes it easier to differentiate them from lesions, and it may help prevent unnecessary treatment.

Genome-wide association study of hippocampal atrophy rate in non-demented elders

Hippocampal atrophy rate has been correlated with cognitive decline and its genetic modifiers are still unclear. Here we firstly performed a genome-wide association study (GWAS) to identify genetic loci that regulate hippocampal atrophy rate. Six hundred and two non-Hispanic Caucasian elders without dementia were included from the Alzheimer's Disease Neuroimaging Initiative cohort. Three single nucleotide polymorphisms (SNPs) (rs4420638, rs56131196, rs157582) in the TOMM40-APOC1 region were associated with hippocampal atrophy rate at genome-wide significance and 3 additional SNPs (in TOMM40 and near MIR302F gene) reached a suggestive level of significance. Strong linkage disequilibrium between rs4420638 and rs56131196 was found. The minor allele of rs4420638 (G) and the minor allele of rs157582 (T) showed associations with lower Mini-mental State Examination score, higher Alzheimer Disease Assessment Scale-cognitive subscale 11 score and smaller entorhinal volume using both baseline and longitudinal measurements, as well as with accelerated cognitive decline. Moreover, rs56131196 (P = 1.96 × 10-454) and rs157582 (P = 9.70 × 10-434) were risk loci for Alzheimer's disease. Collectively, rs4420638, rs56131196 and rs157582 were found to be associated with hippocampal atrophy rate. Besides, they were also identified as genetic loci for cognitive decline.

Hippocampal sulcal cavities: prevalence, risk factors and association with cognitive performance. The SMART-Medea study and PREDICT-MR study

Hippocampal sulcal cavities (HSCs) are frequently observed on MRI, but their etiology and relevance is unclear. HSCs may be anatomical variations, or result from pathology. We assessed the presence of HSCs, and their cross-sectional association with demographics, vascular risk factors and cognitive functioning in two study samples. Within a random sample of 92 patients with vascular disease from the SMART-Medea study (mean age = 62, SD = 9 years) and 83 primary care patients from the PREDICT-MR study (mean age = 62, SD = 12 years) one rater manually scored HSCs at 1.5 T 3D T1-weighted coronal images blind to patient information. We estimated relative risks of age, sex and vascular risk factors with presence of HSCs using Poisson regression with log-link function and robust standard errors adjusted for age and sex. Using ANCOVA adjusted for age, sex, and education we estimated the association of the number of HSCs with memory, executive functioning, speed, and working memory. In the SMART-Medea study HSCs were present in 65% and in 52% in the PREDICT-MR study (χ2 = 2.99, df = 1, p = 0.08). In both samples, no significant associations were observed between presence of HSCs and age (SMART-Medea: RR = 1.00; 95%CI 0.98-1.01; PREDICT-MR: RR = 1.01; 95%CI 0.99-1.03), sex, or vascular risk factors. Also, no associations between HSCs and cognitive functioning were found in either sample. HSCs are frequently observed on 1.5 T MRI. Our findings suggest that, in patients with a history of vascular disease and primary care attendees, HSCs are part of normal anatomic variation of the human hippocampus rather than markers of pathology.

Age-related differences on a new test of temporal order memory for everyday events

We developed a new test to examine incidental temporal order memory for a self-generated sequence of tasks one might complete in everyday life. Young and older adults were given 10 cards, each listing a task one might accomplish in a typical day. Participants were asked to self-generate a "to do" list by placing the 10 cards in a sequence representing the order in which they would accomplish the tasks, but were not informed of a subsequent memory test. We assessed immediate free recall, delayed free recall, and delayed cued recall for the order of the tasks in the sequence. Older adults were significantly impaired relative to young adults on immediate free recall, delayed free recall, and delayed cued recall. Correlation analyses with standardized neuropsychological tests provide preliminary evidence for construct validity for our test, which is portable and can be rapidly administered in clinical or laboratory settings.

Candidate-gene analysis of white matter hyperintensities on neuroimaging

BACKGROUND

White matter hyperintensities (WMH) are a common radiographic finding and may be a useful endophenotype for small vessel diseases. Given high heritability of WMH, we hypothesised that certain genotypes may predispose individuals to these lesions and consequently, to an increased risk of stroke, dementia and death. We performed a meta-analysis of studies investigating candidate genes and WMH to elucidate the genetic susceptibility to WMH and tested associated variants in a new independent WMH cohort. We assessed a causal relationship of WMH to methylene tetrahydrofolate reductase (MTHFR).

METHODS

Database searches through March 2014 were undertaken and studies investigating candidate genes in WMH were assessed. Associated variants were tested in a new independent ischaemic cohort of 1202 WMH patients. Mendelian randomization was undertaken to assess a causal relationship between WMH and MTHFR.

RESULTS

We identified 43 case-control studies interrogating eight polymorphisms in seven genes covering 6,314 WMH cases and 15,461 controls. Fixed-effects meta-analysis found that the C-allele containing genotypes of the aldosterone synthase CYP11B2 T(-344)C gene polymorphism were associated with a decreased risk of WMH (OR=0.61; 95% CI, 0.44 to 0.84; p=0.003). Using mendelian randomisation the association among MTHFR C677T, homocysteine levels and WMH, approached, but did not reach, significance (expected OR=1.75; 95% CI, 0.90-3.41; observed OR=1.68; 95% CI, 0.97-2.94). Neither CYP11B2 T(-344)C nor MTHFR C677T were significantly associated when tested in a new independent cohort of 1202 patients with WMH.

CONCLUSIONS

There is a genetic basis to WMH but anonymous genome wide and exome studies are more likely to provide novel loci of interest.

ACE polymorphism and use of ACE inhibitors: effects on memory performance

Memory is an important cognition function, being fundamental to the development and independence of individuals. Our aim was to investigate the influence apolipoprotein E (APOE) and angiotensin I-converting enzyme (ACE) polymorphism and ACE inhibitors use, besides their interaction on memory performance of healthy subjects over 50 years. The sample consisted of 205 subjects assessed for five types of episodic memory, using Wechsler Memory Scale-Revised (WMS-R), who answered a questionnaire about drug use and were assessed for the ACE insertion/deletion polymorphism and APOE polymorphism. We found no influence of the APOE gene. The use of ACE inhibitors beneficially influenced learning ability scores (p = 0.02). Besides, I allele carriers of ACE polymorphism showed higher verbal memory scores compared with homozygous DD. Also, we observed an interaction influencing learning ability between the ACE polymorphism and the use of inhibitors, the beneficial influence of the I allele was present only in individuals who make use of ACE inhibitors. We conclude that the ACE gene has influence on memory performance, and that this influence is modulated by ACE inhibitors use.

Cognitive impairments associated with medial temporal atrophy and white matter hyperintensities: an MRI study in memory clinic patients

In this retrospective study, we investigated the independent effects of white matter hyperintensities (WMH) and hippocampal atrophy on cognitive functions in a broad sample of patients seen in a memory clinic. To ensure generalizability, these associations were examined irrespective of diagnosis and with minimal exclusion criteria. Next to these independent effects, interactions between WMH and hippocampal atrophy were examined. Between January 2006 and September 2011 a total of 500 patients visited the memory clinic, 397 of whom were included. Magnetic resonance images of 397 patients were visually analyzed for WMH, medial temporal atrophy (MTA), and global atrophy. We evaluated the association of WMH and MTA with the following cognitive domains: global cognition, episodic memory, working memory, executive function and psychomotor speed. Main effects and interaction effects were examined by means of correlation and regression analyses. In the regression analyses, we controlled for potential confounding effects of global atrophy. The correlational results revealed that WMH were associated with global cognition, executive function and psychomotor speed, whereas a trend was found for episodic memory. MTA was associated with all these four cognitive domains; an additional trend was observed for working memory. Hierarchical regression analyses revealed main independent effects of MTA for episodic memory, executive function, psychomotor speed and global cognition; WMH were only associated with global cognition. The interaction between MTA and WMH was significant for episodic memory only. This study demonstrates that predominantly MTA is an independent predictor not only for memory function, with which is it classically associated, but also for global cognition and executive function. Taken together, MTA may be an important correlate of cognitive deficits found in people attending the memory clinic.

Hippocampal T2 hyperintensities on 7 Tesla MRI

Hippocampal focal T2 hyperintensities (HT2Hs), also referred to as hippocampal sulcal cavities, are a common finding on Magnetic Resonance (MR) images. There is uncertainty about their etiology and clinical significance. In this study we aimed to describe these HT2Hs in more detail using high resolution 7 Tesla MR imaging, addressing 1) the MR signal characteristics of HT2Hs, 2) their occurrence frequency, 3) their location within the hippocampus, and 4) their relation with age. We also performed an explorative post-mortem study to examine the histology of HT2Hs. Fifty-eight persons without a history of invalidating neurological or psychiatric disease (mean age 64 ± 8 years; range 43-78 years), recruited through their general practitioners, were included in this study. They all underwent 7 Tesla MRI, including a T1, T2, and FLAIR image. MR signal characteristics of the HT2Hs were assessed on these images by two raters. Also, the location and number of the HT2Hs were assessed. In addition, four formalin-fixed brain slices from two subjects were scanned overnight. HT2Hs identified in these slices were subjected to histopathological analysis. HT2Hs were present in 97% of the subjects (median number per person 10; range 0-20). All HT2Hs detected on the T2 sequence were hypointense on T1 weighted images. Of all HT2Hs, 94% was hypointense and 6% hyperintense on FLAIR. FLAIR hypointense HT2Hs were all located in the vestigial sulcus of the hippocampus, FLAIR hyperintense HT2Hs in the hippocampal sulcus or the gray matter. Post-mortem MRI and histopathological analysis suggested that the hypointense HT2Hs on FLAIR were cavities filled with cerebrospinal fluid. A hyperintense HT2H on FLAIR proved to be a microinfarct upon microscopy. In conclusion, hippocampal T2Hs are extremely common and unrelated to age. They can be divided into two types (hypo- and hyperintense on FLAIR), probably with different etiology.

Functional regulation of Alu element of human angiotensin-converting enzyme gene in neuron cells

The angiotensin-converting enzyme (ACE) insertion/deletion (I/D) genotype and its protein activity have been widely implicated to be associated with Alzheimer's disease (AD). However, whether the insertion sequence, Alu element, in intron 16 of the human ACE gene plays a functional role remains uncertain. To investigate the influence of the I/D polymorphism on ACE promoter, we recombined the I and D form fragments with the human ACE promoter sequence before the reporter gene in pSEAP-Basic2 vector. The effect of the Alu element on regulating the transcriptional activity of ACE promoter was examined using transient transfection in SH-SY5Y cells. We found that the I form fragment upregulated the transcriptional activity of ACE promoter by approximately 70% but that the D form fragment did not. Our study first reveals that Alu sequence in human ACE gene possesses a regulatory function on the ACE promoter activity in neuron. This novel finding bridges the gap between the association of ACE I/D genotype with AD, and suggests that Alu sequence is not merely a "junk" DNA in human ACE gene.

A comprehensive genetic association study of Alzheimer disease in African Americans

OBJECTIVES

To evaluate the association of genetic variation with late-onset Alzheimer disease (AD) in African Americans, including genes implicated in recent genome-wide association studies of whites.

DESIGN

We analyzed a genome-wide set of 2.5 million imputed markers to evaluate the genetic basis of AD in an African American population.

SUBJECTS

Five hundred thirteen well-characterized African American AD cases and 496 cognitively normal African American control subjects.

SETTING

Data were collected from multiple sites as part of the Multi-Institutional Research on Alzheimer Genetic Epidemiology (MIRAGE) Study and the Henry Ford Health System as part of the Genetic and Environmental Risk Factors for Alzheimer Disease Among African Americans (GenerAAtions) Study.

RESULTS

Several significant single-nucleotide polymorphisms (SNPs) were observed in the region of the apolipoprotein E gene (APOE). After adjusting for the confounding effects of APOE genotype, one of these SNPs, rs6859 in PVRL2, remained significantly associated with AD (P = .0087). Association was also observed with SNPs in CLU, PICALM, BIN1, EPHA1, MS4A, ABCA7, and CD33, although the effect direction for some SNPs and the most significant SNPs differed from findings in data sets consisting of whites. Finally, using the African American genome-wide association study data set as a discovery sample, we obtained suggestive evidence of association with SNPs for several novel candidate genes.

CONCLUSIONS

Some genes contribute to AD pathogenesis in both white and African American cohorts, although it is unclear whether the causal variants are the same. A larger African American sample will be needed to confirm novel gene associations, which may be population specific.

Genetic risk factors for longitudinal changes in structural MRI in former organolead workers

This study examined associations between polymorphisms in three genes, apolipoprotein E (APOE), angiotensin converting enzyme (ACE), and vitamin D receptor (VDR), and longitudinal change in brain volumes and white matter lesions (WML) as well as effect modification by cardiovascular factors and tibia lead concentrations. Two MRIs, an average of 5 years apart, were obtained for 317 former organolead workers and 45 population-based controls. Both regions-of-interest and voxel-wise analyses were conducted. APOE ε3/ε4 and ε4/ε4 genotypes were associated with less decline in white matter volumes. There was some evidence of interaction between genetic polymorphisms and cardiovascular risk factors (ACE and high-density lipoprotein; VDR and diabetes) on brain volume decline. The VDR FokI ff genotype was associated with an increase in WML (no association for APOE or ACE). This study expands our understanding of how genetic precursors of dementia and cardiovascular diseases are related to changes in brain structure.

Genetic influences on Alzheimer's disease: evidence of interactions between the genes APOE, APOC1 and ACE in a sample population from the South of Brazil

Alzheimer's disease is a complex neurodegenerative disorder. Several genes have been suggested as Alzheimer's susceptibility factors, the apolipoprotein E (APOE) gene being an established susceptibility gene and the genes coding angiotensin-converting enzyme (ACE) and apolipoprotein C1 (APOC1) being considered possible candidate genes for the disease. The objective of this study was to investigate the association of ACE and APOC1 gene polymorphisms with susceptibility to Alzheimer's disease and dementia in general, both alone and combined with the APOE gene. Forty-seven patients with dementia in general (35 of them with Alzheimer's disease) and 85 controls were investigated. The haplotypes E*3/-317*ins and E*4/-317*ins of APOE/APOC1 genes were significantly more frequent in the groups with Alzheimer's disease and dementia in general (P < 0.001). The frequency of the ACE*ins allele was also greater in the groups with Alzheimer's disease and dementia in general (P = 0.022; P = 0.045), but genotype frequencies were only different in groups without the E*4/-317*ins haplotype (P = 0.012 for Alzheimer's disease; P = 0.04 for dementia). Our data point to important genetic interactions involved in these diseases.

Neuroimaging measures as endophenotypes in Alzheimer's disease

Late onset Alzheimer's disease (AD) is moderately to highly heritable. Apolipoprotein E allele ε4 (APOE4) has been replicated consistently as an AD risk factor over many studies, and recently confirmed variants in other genes such as CLU, CR1, and PICALM each increase the lifetime risk of AD. However, much of the heritability of AD remains unexplained. AD is a complex disease that is diagnosed largely through neuropsychological testing, though neuroimaging measures may be more sensitive for detecting the incipient disease stages. Difficulties in early diagnosis and variable environmental contributions to the disease can obscure genetic relationships in traditional case-control genetic studies. Neuroimaging measures may be used as endophenotypes for AD, offering a reliable, objective tool to search for possible genetic risk factors. Imaging measures might also clarify the specific mechanisms by which proposed risk factors influence the brain.

Hippocampal sulcal cavities: prevalence, risk factors and relationship to memory impairment

While hippocampal volumes have been extensively examined in neuropsychiatric disorders and ageing, small areas of signal variation within the hippocampus commonly observed on MRI, described as hippocampal sulcal cavities (HSCs), have received less attention. We review the published literature on HSCs to examine their prevalence, putative aetiological factors such as hypertension, and possible cognitive correlates. HSCs were reported in 77% (66% weighted mean) of patients with memory disorders and 48% (47% weighted mean) of controls, and the prevalence increased with age in healthy subjects (r=0.64, p=0.047). A number of studies reported hypertension as a risk factor, and related their presence to poorer memory function. Further work is needed to fully understand the clinical significance of these lesions.

The D-allele of ACE insertion/deletion polymorphism is associated with regional white matter volume changes and cognitive impairment in remitted geriatric depression

Prior studies suggested that angiotensin-converting enzyme (ACE) affected vascular homeostasis and degradation of amyloid beta (Abeta ). It is associated with the therapeutic outcome in major depression. The aim of this study was to investigate the association between angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism and structural abnormalities in remitted geriatric depression (RGD), and test the relationship of neuropsychological performances and regional white matter volumes. 31 RGD patients were recruited and neuropsychological tests, magnetic resonance imaging (MRI) and genotype of ACE I/D were examined for each subject. The differences in regional white matter volume were tested between I homozygotes and D-allele carriers (I/D or D/D genotype) by optimized VBM. D-allele carriers exhibited significantly smaller white matter volumes of right superior frontal gyrus (SFG) and right anterior cingulated gyrus (ACG), but had larger volumes of left middle temporal gyrus (MTG) and right middle occipital gyrus (MOG) than I homozygotes (P < 0.001). Meanwhile, there was a significant positive correlation between white matter volume enlargement of left MTG and Symbol Digit Modalities Test (SDMT) (r = 0.456, P = 0.043), and the reduction of right ACG was negatively related to Clock Drawing Test (CDT) performance (r = -0.445, P = 0.050) in D-allele carriers. The finding suggests that ACE can modulates the pathology of RGD, the left MTG and right ACG might be involved in the pathophysiology of cognitive dysfunction in RGD patients.

Assessing mental flexibility: neuroanatomical and neuropsychological correlates of the Trail Making Test in elderly people

The Trail Making Test part B (TMT-B) is highly sensitive to age-related changes in the brain and cognitive function. However, the precise contribution of periventricular hyperintensities (PVH), deep white matter hyperintensities (DWMH), and medial temporal lobe atrophy (MTA) to task performance remains unspecified. Similarly, diminished performance may be due to deficient flexibility functions, but also to other age-related cognitive decline (e.g., mental slowing). The aim of the present study was to determine neuroanatomical (PVH, DWMH, MTA) and neuropsychological (working memory, executive function, speed and attention, episodic memory) predictors of TMT-B performance in elderly people. Results showed that MTA was the strongest predictor of TMT-B performance. The predictive value of the neuropsychological scores differed among the various TMT-B variables. For example, all neuropsychological domains predicted the TMT-B total completion time, whereas only executive function predicted the ratio score (TMT-B/A). We conclude that MTA is a very important predictor of TMT-B performance in elderly people. Furthermore, multiple cognitive functions are involved in TMT-B performance and a mild decline in any of these functions may result in diminished TMT-B performance. Therefore it is crucial to use the ratio score when one wishes to examine executive function ability.

The role of white matter hyperintensities and medial temporal lobe atrophy in age-related executive dysfunctioning

Various studies support an association between white matter hyperintensities (WMH) and deficits in executive function in nondemented ageing. Studies examining executive functions and WMH have generally adopted executive function as a phrase including various functions such as flexibility, inhibition, and working memory. However, these functions include distinctive cognitive processes and not all may be affected as a result of WMH. Furthermore, atrophy of the medial temporal lobe (MTA) is frequently observed in ageing. Nevertheless, in previous studies of nondemented ageing MTA was not considered when examining a relationship between white matter and executive function. The goal of the present study was to examine how WMH and MTA relate to a variety of executive functions, including flexibility, fluency, inhibition, planning, set shifting, and working memory. Strong correlations were observed between WMH and MTA and most of the executive functions. However, only MTA was related to flexibility and set shifting performance. Regression analysis furthermore showed that MTA was the strongest predictor of working memory, after which no further significant association with WMH was noted. Alternatively, both MTA and periventricular hyperintensities independently predicted inhibition performance. These findings emphasize the importance of MTA when examining age-related decline in executive functioning.

Independent Cognitive Effects of Atrophy and Diffuse Subcortical and Thalamico-Cortical Cerebrovascular Disease in Dementia

Background and Purpose— Brain atrophy, cortical infarction, and subcortical ischemic vasculopathy have all been associated with cognitive dysfunction. The interrelationships between these pathologies and their independent contributions to cognitive function remain unclear. Despite the high frequency of Alzheimer disease (AD) in those with clinically diagnosed vascular dementia, and the frequent findings of vascular disease in those with clinically diagnosed AD, many studies of brain-behavior relationships in dementia consider these populations separately. The present study sought to identify the correlates of independent domains of cognitive impairment in an unselected sample across a large range of severity and overlap of AD and VaD.

Methods— Two hundred five individuals from the Sunnybrook Dementia Study recruited from a university Memory clinic had detailed neuropsychological testing and MRI quantification using a multi-step postprocessing algorithm. A factor analysis of the cognitive protocol yielded a 3-factor solution, provisionally labeled: (1) short-term memory and language, (2) attention and working memory, and (3) mental flexibility.

Results— A factor analysis of brain measures identified 3 independent factors with measures of (1) brain atrophy, (2) subcortical vascular disease, and (3) strategic infarcts (anterior-medial thalamus and cortical infarcts). After accounting for the effects of age and education, measures of brain atrophy were the strongest correlates of all cognitive domains. Small vessel disease was independently associated with general severity, impaired short-term memory/language, and reduced mental flexibility, but not with poor working memory, presumably through disruption of frontal-subcortical connections. In contrast, strategic infarcts to anterior-medial thalamus and cortical gray matter were associated with poor short-term and working memory, but not with impairments in mental flexibility or global severity measures.

Conclusions— These data support the hypothesis that the thalamico-cortical network subserves both short-term and working memory. The findings also suggest that each type of pathology (atrophy, small vessel disease, and strategic infarcts) contribute independently to the pattern of cognitive disabilities associated with dementia. Particular attention to cerebrovascular disease in deep white or gray matter structures of the thalamico-cortical system is certainly warranted.

Hippocampus and amygdala volumes in a random community-based sample of 60-64 year olds and their relationship to cognition

Reduced volumes of the hippocampus (HC) and amygdala (AG) are potential biomarkers for Alzheimer's disease (AD) and other neuropsychiatric disorders. Published studies on HC and AG volumes suffer from methodological limitations, and a valid and reliable normative database does not exist. This study aimed to establish a database of HC and AG volumes from a large community sample of participants 60-64 years old and relate them to cognition. A total of 452 randomly selected participants (from 622 approached) were retained in the study (238 males, 214 females), and all received brain MRI scans, as well as cognitive and physical assessments. HC and AG volumes were estimated from manual tracings on T1-weighted images, and intracranial volume (ICV) was obtained from an automated program. In both sexes, right hippocampi were larger than left, while left amygdala were larger than right. The only correlation to remain significant after normalization was left HC volume and percent retention of a word list in females. This study provides a HC and AG volumetrics database and describes its relationship with cognitive performance in a representative sample using a standard methodology that will be a reference for future studies. It will therefore have clinical applicability in early AD and other disorders.

Differential cross-sectional and longitudinal impact of APOE genotype on hippocampal volumes in nondemented older adults

BACKGROUND/AIMS

Because of conflicting findings across studies, we sought to better determine the relationship between apolipoprotein E (APOE) genotype, hippocampal volume, and cognitive performance in nondemented older adults.

METHODS

Two groups ofolder adults, as determined by their APOE epsilon4 allele status, received structural MRI and comprehensive neuropsychological testing on two occasions separated on average by 17 months.

RESULTS

Cross-sectional comparisons by APOE group revealed no differences in hippocampal volumes, although longitudinal percent reduction in hippocampal volume was significantly greater for those possessing the APOE epsilon4 allele. Relationship between hippocampal volumes and memory performance was strongly impacted by diagnosis of mild cognitive impairment.

CONCLUSIONS

APOE epsilon4 allele appears to significantly impact rate of volume loss over time in the hippocampus in nondemented older adults, and detailed cognitive characterization of the sample is necessary to reliably interpret the relationship between cognition and brain structure.

Deletion/Insertion Polymorphism of the Angiotensin-Converting Enzyme Gene and White Matter Hyperintensities in Dementia: A Pilot Study

OBJECTIVES

To examine the association between the angiotensin-converting enzyme (ACE) deletion/insertion (D/I) polymorphism and white matter hyperintensities (WMHs) in patients with dementia.

DESIGN

Observational pilot study with adjustment for potential confounders using analysis of covariance.

SETTING

Secondary care old-age psychiatry services in greater Manchester, United Kingdom.

PARTICIPANTS

Ninety-seven patients with dementia: 49 with Alzheimer's disease (AD, National Institute of Neurological and Communicative Disorders and Stroke/Alzheimer's Disease and Related Disorders Association criteria) and 48 with vascular dementia (VaD, National Institute of Neurological Disorders and Stroke/Association Internationale pour la Recherche et l'Enseignement en Neurosciences criteria).

MEASUREMENTS

The ACE D/I polymorphism, WMHs (deep WMHs (DWMHs) and periventricular hyperintensities (PVHs)) on T2-weighted magnetic resonance imaging, and potential cardiovascular confounders.

RESULTS

The D/D polymorphism of the ACE genotype was associated with severity of DWMH (P = .005) but not PVH (P = .34), corrected for age, cardiovascular risk factors, and type of dementia. Post hoc analyses were limited by statistical power but suggested an interaction with the apolipoprotein E epsilon4 allele.

CONCLUSION

The results support previous observations that genetic factors influence the development of WMHs in dementia. The involvement of the ACE D/I polymorphism in the pathogenesis of DWMHs in dementia (AD and VaD), by a mechanism that is independent of its association with cardiovascular risk factors, should be confirmed in a large population-based sample.

ACE genotype and cognitive decline in an African-Caribbean population

The insertion/deletion (I/D) polymorphism of the angiotensin I converting enzyme (ACE) gene is believed to influence risk of cerebrovascular disease. However, associations with cognitive outcomes remain controversial. As far as we are aware, all studies to date have been carried out in white American or European populations. African-Caribbean populations have high prevalence rates of hypertension, diabetes and cerebrovascular disease but risk factors for cognitive outcomes remain under-researched. In a UK community sample of 148 African-Caribbean people aged 55-75 years, we investigated the association between ACE genotype and cognitive decline over 3 years using a battery of repeated tests. No direct association was found between ACE genotype and decline. However, the association between increased age and cognitive decline was significantly stronger in people with the ACE DD genotype (odds ratio 3.6 per 5-year increase, 95% CI: 1.9-6.7) compared to those with ID/II genotype (odds ratio 0.7, 95% CI 0.4-1.2). This interaction was particularly strong for decline in verbal memory and was not apparently mediated by vascular risk factors measured at baseline.

Apolipoprotein E genotype and subcortical vascular lesions in older depressed patients and control subjects

BACKGROUND

Several studies have linked geriatric depression with cerebrovascular disease. The apolipoprotein E gene (APOE) epsilon 4 allele has been associated with a variety of late-life neuropsychiatric disorders, including Alzheimer's disease, vascular dementia, and depression.

METHODS

The sample consisted of 145 elderly depressive individuals and 100 nondepressed elderly control subjects. After a standardized clinical assessment, all subjects underwent a magnetic resonance imaging brain scan. Volumes of subcortical white and gray matter lesions were determined using a semi-automated method. Apolipoprotein E genotype was determined on blood sample using a standard protocol. A series of linear regression models were developed to assess the relationships between APOE genotype and white and gray matter lesion volumes.

RESULTS

Older age, lower Mini-Mental State Examination score, and having any APOE epsilon 4 allele were each correlated with gray-matter lesion volume in depressed patients. Apolipoprotein E genotype was not associated with any lesion volume among control subjects. In a subsequent linear regression model, gray matter lesion volume was associated with older age, having at least one APOE epsilon 4 allele, and white matter lesion volume among depressed patients.

CONCLUSIONS

These results are consistent with previous reports linking cerebrovascular disease and APOE genotype. Further studies are needed to replicate this finding in elderly depressive individuals and to explain the relationship between the APOE locus and development of central nervous system vascular pathology.

Apolipoproteins E and C1 and brain morphology in memory impaired elders

Previous research has shown that polymorphisms of the apolipoproteins E ( APOE) and APOC1 represent genetic risk factors for dementia and for cognitive impairment in the elderly. The brain mechanisms by which these genetic variations affect behavior or clinical severity are poorly understood. We studied the effect of APOE and APOC1 genes on magnetic resonance imaging measures in a sample of 50 subjects with age-associated memory impairment. The APOE E4 allele was associated with reduced left hippocampal volumes and APOE*E3 status was associated with greater frontal lobe white matter volumes. However, no APOE effects were observed when analyses accounted for other potential confounding variables. The effects of APOC1 on hippocampal volumes appeared to be more robust than those of the APOE polymorphism. However, no modulatory effects on brain morphology outside the medial temporal lobe region were observed when demographic variables, clinical status, and other anatomical brain measurements were taken into consideration. Our results suggest that the role of the APOC1 polymorphism in brain morphology of the cognitively impaired elderly should be examined in further studies.

Genetics of leukoaraiosis

Computed tomography and magnetic resonance imaging of the brains of elderly individuals frequently show areas of altered signal intensity in the periventricular and subcortical white matter, referred to as leukoaraiosis. Although mildly affected individuals appear asymptomatic, larger burdens of leukoaraiosis are associated with deficits of cognition and gait. Histopathologically, areas of leukoaraiosis invariably show sclerosis, luminal narrowing, and tortuosity of small arteries and arterioles, accompanied by variable degrees of gliosis, demyelination, and axonal loss resulting from ischemia. Genetic variation plays a substantial role in interindividual differences in the volume of leukoaraiosis and its associated adverse clinical outcomes. Characterizing genetic factors contributing to interindividual differences in leukoaraiosis has the potential to enhance understanding of molecular determinants of ischemic brain injury and lead to new approaches to the diagnosis, evaluation, treatment, and prevention of this common form of vascular dementia.

Relationship among (1)H-magnetic resonance spectroscopy, brain volumetry and genetic polymorphisms in humans with memory impairment

We investigated the relationship among neuroanatomical, neurochemical and genetic variables in 44 subjects with age-related memory impairment. Hydrogen magnetic resonance spectroscopy was used to determine N-acetyl/creatine (NAA/Cr) concentrations in basal ganglia and medial temporal regions. Volumetric measures were obtained for caudate nucleus and hippocampus. Genetic polymorphisms examined included apolipoproteins (APO) E and CI, angiotensin converting enzyme and dopamine D2 receptor TaqI genes. Age was found to be negatively correlated with hippocampal and basal ganglia volumes, but not with neurochemical values. Multiple regression analyses showed that the APOC1 polymorphism was the only variable which predicted NAA/Cr values in basal ganglia. NAA/Cr metabolites in the medial temporal lobe but not in the basal ganglia region were related with lower performance in verbal memory.

Dopamine DRD2 Taq I polymorphism associates with caudate nucleus volume and cognitive performance in memory impaired subjects

We studied the relationship among dopamine receptor D2 (DRD2) Taq I genetic polymorphism, caudate nucleus volumetry as measured using MRI and neuropsychological functions in 49 memory impaired older people. Compared with DRD2 A1 carriers, subjects homozygous for the DRD2 A2 allele performed poorer in a measure of general cognitive functioning (MMSE) and in long term verbal memory, and presented reduced left caudate nucleus volumes. Caudate nucleus atrophy correlated with cognitive measures influenced by the genetic polymorphism and with visual memory performance. Our findings suggest that among the aged with cognitive impairments, the homozygous status for the A2 allele of the DRD2 Taq I polymorphism is associated with diminished cognitive performance and increased atrophy in the striatum.

Relation of Apo E and ACE genes to cognitive performance in chronic alcoholic patients

Apolipoprotein E epsilon4 and ACE genes have been related to several conditions involving cognitive impairment, including Alzheimer's disease, normal ageing and cerebrovascular disease. However, it has not been established whether their genotypes are associated with alcoholism or its cognitive functioning. Genotypic distributions of 140 chronic alcoholic patients were compared with a non-alcoholic sample, and the cognitive performance of a subsample of the alcoholic subjects was assessed with standard neuropsychological tests. No differences in allele or genotype distributions of Apo E or ACE genes were found when comparing controls and alcoholics (Apo E epsilon2/2; patients 1.4%, controls 0% p < 0.06; epsilon2/epsilon3; patients 9.3%, controls 6.6% p < 0.29; epsilon2/epsilon4; patients 0%, controls 1% p < 0.31; epsilon3/epsilon3 patients 71.4%, controls 72% p < 0.89; epsilon3/epsilon4; patients 15.7%, controls 19.2%, p < 0.36; epsilon4/epsilon4; patients 2.1%, controls 1.2% p < 0.44; ACE D/D; patients 35%, controls 28.5% p < 0.14; I/D; patients 47.5%, controls 51.1% p < 0.51; I/I; patients 14.5%, controls 20.4% p < 0.19). In terms of cognitive performance, epsilon4/epsilon3 patients did better on visuoconstructive (p < 0.001) and visual memory (p < 0.04) functions compared with epsilon2/epsilon3 bearers. Furthermore, ACE D/D patients performed better on a test of abstract reasoning (p < 0.03) compared with the ACE I/I homozygous group. The cognitive results suggest that Apo E or ACE genotypes may modify the effects of ethanol on cognitive deterioration in alcoholic patients. However, the data do not support an association between the Apo E epsilon4 allele and reduced cognitive performance in alcoholism.

Current awareness in geriatric psychiatry. Bibliography

In order to keep subscribers up-to-date with the latest developments in their field, John Wiley &amp: Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of geriatric psychiatry. Each bibliography is divided into 9 sections: 1 Books, Reviews &amp: Symposia; 2 General; 3 Assessment; 4 Epidemiology; 5 Therapy; 6 Care; 7 Dementia; 8 Depression; 9 Psychology. Within each section, articles are listed in alphabetical order with respect to author. If, in the preceding period, no publications are located relevant to any one of these headings, that section will be omitted