APOE-epsilon4 and APOE -491A polymorphisms in individuals with subjective memory loss

The impact of APOE and smoking history on cognitive function in older, long-term breast cancer survivors

PURPOSE

This study aims to determine whether older breast cancer survivors score lower on neuropsychological tests compared to matched non-cancer controls and to test the hypotheses that survivors who were APOE ε4 carriers would have the lowest cognitive performance but that smoking history would decrease the negative effect of ε4 on cognition.

METHODS

Female breast cancer survivors who had been diagnosed and treated at age 60 or older and were 5-15-year survivors (N = 328) and age and education matched non-cancer controls (N = 162) were assessed at enrollment and at 8-, 16-, and 24-month follow-ups with standard neuropsychological and psychological assessments. Blood for APOE genotyping was collected, and smoking history was assessed at enrollment. Participants were purposely recruited so that approximately 50% had a history of treatment with chemotherapy or no chemotherapy and approximately 50% had a smoking history.

RESULTS

After adjusting for age, cognitive reserve, depression, and fatigue, breast cancer survivors scored significantly lower on all domains of cognitive function. A significant two-way interaction demonstrated that the negative effect of ε4 on cognitive performance was stronger among survivors. A significant three-way interaction supported the hypothesis that smoking history had a protective effect on cognitive function in ε4 carriers that was more pronounced in the controls than the survivors.

CONCLUSIONS

The results support the long-term cognitive impact of breast cancer diagnosis and treatments on older, disease-free survivors, particularly for ε4 carriers. The results also emphasize the importance of assessing smoking history when examining APOE and cognition and are an example of the complex interactions of age, genetics, health behaviors, and disease history in determining cognitive function.

IMPLICATIONS FOR CANCER SURVIVORS

These results help explain why only a subset of breast cancer survivors appear to be vulnerable to cognitive problems.

Genetic association between the APOE ε4 allele, toxicant exposures and Gulf war illness diagnosis

INTRODUCTION

Exposure to nerve agents, pyridostigmine bromide (PB), pesticides, and oil-well fires during the 1991 Gulf War (GW) are major contributors to the etiology of Gulf War Illness (GWI). Since the apolipoprotein E (APOE) ε4 allele is associated with the risk of cognitive decline with age, particularly in the presence of environmental exposures, and cognitive impairment is one of the most common symptoms experienced by veterans with GWI, we examined whether the ε4 allele was associated with GWI.

METHODS

Using a case-control design, we obtained data on APOE genotypes, demographics, and self-reported GW exposures and symptoms that were deposited in the Boston Biorepository and Integrative Network (BBRAIN) for veterans diagnosed with GWI (n = 220) and healthy GW control veterans (n = 131). Diagnosis of GWI was performed using the Kansas and/or Center for Disease Control (CDC) criteria.

RESULTS

Age- and sex-adjusted analyses showed a significantly higher odds ratio for meeting the GWI case criteria in the presence of the ε4 allele (Odds ratio [OR] = 1.84, 95% confidence interval [CI = 1.07-3.15], p ≤ 0.05) and with two copies of the ε4 allele (OR = 1.99, 95% CI [1.23-3.21], p ≤ 0.01). Combined exposure to pesticides and PB pills (OR = 4.10 [2.12-7.91], p ≤ 0.05) as well as chemical alarms and PB pills (OR = 3.30 [1.56-6.97] p ≤ 0.05) during the war were also associated with a higher odds ratio for meeting GWI case criteria. There was also an interaction between the ε4 allele and exposure to oil well fires (OR = 2.46, 95% CI [1.07-5.62], p ≤ 0.05) among those who met the GWI case criteria.

CONCLUSION

These findings suggest that the presence of the ε4 allele was associated with meeting the GWI case criteria. Gulf War veterans who reported exposure to oil well fires and have an ε4 allele were more likely to meet GWI case criteria. Long-term surveillance of veterans with GWI, particularly those with oil well fire exposure, is required to better assess the future risk of cognitive decline among this vulnerable population.

Validation and Reliability of the Alzheimer's Disease-Commonwealth Scientific and Industrial Research Organisation Food Frequency Questionnaire

Accuracy in measuring intake of dietary constituents is an important issue in studies reporting the associations between diet and chronic diseases. We modified a Commonwealth Scientific and Industrial Research Organisation (CSIRO) food frequency questionnaire (FFQ) to include foods of interest in the field of Alzheimer's disease (AD) research. The aim of the current study was to determine the reliability and validity of the AD-CSIROFFQ in 148 cognitively normal older adults. The AD-CSIROFFQ was completed before and after completion of a four-day weighed food record. Of the 508 food and beverage items reported, 309 had sufficient consumption levels for analysis of reliability. Of the 309 items, over 78% were significantly correlated between the two questionnaire administrations (Spearman's rank correlations). We used two additional methods to assess absolute nutrient intake agreement between the AD-CSIROFFQ and the weighed food records (Pearson's correlation coefficients and Bland-Altman plots) and quintile rankings to measure group level agreement. The adequate correlations observed between questionnaire responses suggest that the AD-CSIROFFQ is reliable. All nutrient intakes were acceptable for ranking of individuals on a group level, whilst the agreement levels with respect to the weighed food records for 11 of the 46 nutrients show validity in terms of their individual level absolute intake. The AD-CSIROFFQ makes an important contribution to the tools available for assessing usual dietary intake in groups of older adults with respect to AD research.

An approach to classifying subjective cognitive decline in community-dwelling elders

INTRODUCTION

Subjective cognitive decline (SCD) may be an early symptomatic manifestation of Alzheimer's disease, though published research largely neglects how to classify SCD in community-based studies.

METHODS

In neuropsychologically intact Einstein Aging Study participants (n = 1115; mean age = 78; 63% female; 30% non-White), we used Cox models to examine the association between self-perceived cognitive functioning at baseline (using three different approaches) and incident amnestic mild cognitive impairment (aMCI) with covariates of age, sex, education, race/ethnicity, general (objective) cognition, depressive symptoms, and four other SCD-related features.

RESULTS

After a median of 3 years, 198 participants developed aMCI. In models that included all the variables, self-perceived cognitive functioning was consistently associated with incident aMCI as were age, general cognition, and perceived control; apolipoprotein E (APOE) ε4 allele status was significant in one model. We set cut points that optimized the diagnostic accuracy of SCD at various time frames.

DISCUSSION

We provide an approach to SCD classification and discuss implications for cognitive aging studies.

Clinicopathological Relationships in an Aged Case of DOORS Syndrome With a p.Arg506X Mutation in the ATP6V1B2 Gene

DOORS [deafness, onychodystrophy, osteodystrophy, intellectual disability (mental retardation), and seizures] syndrome can be caused by mutations in the TBC1D24 and ATP6V1B2 genes, both of which are involved in endolysosomal function. Because of its extreme rarity, to date, no detailed neuropathological assessment has been performed to establish clinicopathological relationships and, thereby, understand better the neurobiology of this disease in aged cases. Accordingly, the aim of the current study was to highlight the clinicopathological characteristics of a novel case with a presumable de novo mutation in the ATP6V1B2 gene from a neuropathological point of view. This Caucasian male patient, who died at the age of 72 years, presented all the typical cardinal signs of DOORS syndrome. In addition, behavioral alterations, pyramidal signs, and Parkinsonism were observed. The p.R506X pathogenic mutation identified in the ATP6V1B2 gene was responsible for the clinical phenotype. The detailed neuropathological assessment revealed a limbic-predominant tauopathy in the forms of argyrophilic grain disease, primary age-related tauopathy, and age-related tau-astrogliopathy. In summary, we present the first detailed clinicopathological report of a patient with DOORS syndrome harboring a pathogenic mutation in the ATP6V1B2 gene. The demonstrated tauopathy may be considered as a consequence of lysosomal and/or mitochondrial dysfunction, similar to that found in Niemann-Pick type C disease, which is another lysosomal disorder characterized by premature neurodegenerative disorder.

APOE-amyloid interaction: Therapeutic targets

Alzheimer's disease (AD) is a devastating neurodegenerative disorder that is growing in prevalence globally. It is the only major cause of death without any effective pharmacological means to treat or slow progression. Inheritance of the ε4 allele of the Apolipoprotein (APO) E gene is the strongest genetic risk factor for late-onset AD. The interaction between APOE and amyloid β (Aβ) plays a key role in AD pathogenesis. The APOE-Aβ interaction regulates Aβ aggregation and clearance and therefore directly influences the development of amyloid plaques, congophilic amyloid angiopathy and subsequent tau related pathology. Relatively few AD therapeutic approaches have directly targeted the APOE-Aβ interaction thus far. Here we review the critical role of APOE in the pathogenesis of AD and some of the most promising therapeutic approaches that focus on the APOE-Aβ interaction.

Motoric cognitive risk syndrome: Integration of two early harbingers of dementia in older adults

Dementia is characterized by a long preclinical phase that may last years to decades before the onset of mild cognitive impairment. Slow gait speed and subjective memory complaint commonly co-occur during this preclinical phase, and each is a strong independent predictor of cognitive decline and dementia. Motoric cognitive risk (MCR) syndrome is a pre-dementia syndrome that combines these two early harbingers of dementia. The risk of cognitive decline or dementia is stronger for MCR than for either slow gait speed or subjective memory complaint alone. Slow gait speed and subjective memory complaint have several common risk factors: cardiovascular disease, diabetes mellitus, abnormal cortisol profiles, low vitamin D levels, brain atrophy with decreased hippocampal volume, and increased deposition of beta-amyloid in the brain. The underlying pathogenesis of MCR remains poorly understood. Metabolomics and proteomics have great potential to provide new insights into biological pathways involved in MCR during the long preclinical phase preceding dementia.

Development of a Human APOE Knock-in Mouse Model for Study of Cognitive Function After Cancer Chemotherapy

Cancer-related cognitive impairment in breast cancer patients exposed to multi-agent chemotherapy regimens is associated with the apolipoprotein E4 (APOE4) allele. However, it is difficult to determine the effects of specific agents on cognitive impairment in human studies. We describe the development of a human APOE knock-in congenic C57BL/6J mouse model to study cancer-related cognitive impairment. Female APOE3 and APOE4 homozygous mice were either left untreated or treated with the most commonly used breast cancer therapeutic agent, doxorubicin. APOE3 and APOE4 mice had similar behaviors in exploratory and anxiety assays, which were affected transiently by doxorubicin treatment. Spatial learning and memory were measured in a Barnes maze: after 4 days of training, control APOE3 and APOE4 mice were able to escape with similar latencies. In contrast, doxorubicin-treated APOE4 mice had markedly impaired learning compared to doxorubicin-treated APOE3 mice at all time points. Voxel-based morphometry of magnetic resonance images revealed that doxorubicin treatment caused significant changes in the cortex and hippocampus of in both APOE3 and APOE4 mouse brains, but the differences were significantly greater in the APOE4 brains. The results indicate that doxorubicin-exposed APOE4 mice recapitulate key aspects of human cancer-related cognitive impairment. These data support the usefulness of this novel preclinical model for future elucidation of the genetic and molecular interactions of APOE genotype with chemotherapy; this model can also allow extension to prospective studies of older mice to study these interactions in the context of aging.

Alzheimer's Disease: A Journey from Amyloid Peptides and Oxidative Stress, to Biomarker Technologies and Disease Prevention Strategies-Gains from AIBL and DIAN Cohort Studies

Worldwide there are over 46 million people living with dementia, and this number is expected to double every 20 years reaching about 131 million by 2050. The cost to the community and government health systems, as well as the stress on families and carers is incalculable. Over three decades of research into this disease have been undertaken by several research groups in Australia, including work by our original research group in Western Australia which was involved in the discovery and sequencing of the amyloid-β peptide (also known as Aβ or A4 peptide) extracted from cerebral amyloid plaques. This review discusses the journey from the discovery of the Aβ peptide in Alzheimer's disease (AD) brain to the establishment of pre-clinical AD using PET amyloid tracers, a method now serving as the gold standard for developing peripheral diagnostic approaches in the blood and the eye. The latter developments for early diagnosis have been largely achieved through the establishment of the Australian Imaging Biomarker and Lifestyle research group that has followed 1,100 Australians for 11 years. AIBL has also been instrumental in providing insight into the role of the major genetic risk factor apolipoprotein E ɛ4, as well as better understanding the role of lifestyle factors particularly diet, physical activity and sleep to cognitive decline and the accumulation of cerebral Aβ.

Synergism between apolipoprotein E Ɛ4 allele and paraoxonase (PON1) 55-M allele is associated with risk of systemic lupus erythematosus

Evidences indicate that abnormal lipid metabolism and lipid peroxidation can affect the progression of complications in systemic lupus erythematosus (SLE) patients. Apolipoprotein E (ApoE) and paraoxonase-1 (PON1) play important role in lipid metabolism and protection of lipid peroxidation. The polymorphisms of ApoE and paraoxonase (PON1) L55M (Met < Leu) allele genes lead to disorders in lipid metabolism and are related to atherosclerosis. This study is the first investigation to examine the possible association between ApoE and PON1-L55M polymorphisms and correlation with serum arylesterase (ARE) activities of PON, levels of malondialdehyde (MDA), neopterin, and lipid lipoprotein in SLE patients from Iranian western population. The present case-control study consisted of 107 SLE patients and 101 gender- and age-matched, unrelated, healthy controls from Iran's western population. The ApoE and PON1-L55M genotypes were identified using PCR-RFLP method. The serum level of MDA, neopterin, lipid levels, and ARE activity were determined by HPLC, commercial kits, and spectrophotometry, respectively. Our results showed that ApoE ε4 and PON1-55M alleles act synergistically to increase the risk of SLE by 1.47 times (p = 0.038). We found that the frequency of ApoE Ɛ3/Ɛ4 genotype was higher in SLE patients (11.2%) compared with control subjects (5%), although the difference was not significant (p = 0.087). This study for the first time not only demonstrates that ApoE Ɛ4 and PON-55M alleles synergistically increase the risk of SLE but also reveals that serum levels of MDA, neopterin, and LDL-C are high in SLE patients. This information may be in value for evaluating SLE progression and in the elucidation of the mechanisms of the disease pathogenesis.

Apolipoprotein E e4 Allele Is Associated with Subjective Cognitive Decline: A Meta-Analysis

BACKGROUND AND PURPOSE

Subjective cognitive decline (SCD) is a condition associated with increased risk of Alzheimer's disease. This study performs a meta-analysis to estimate the prevalence of the Apolipoprotein E e4 (APOE e4) allele in SCD and the association of APOE e4 with SCD.

METHODS

The MEDLINE, EMBASE, and Cochrane Library databases were searched. Meta-analyses were conducted using STATA 12.0 software. When significant heterogeneity was present (I2 >50% and p < 0.05), we conducted stratified and meta-regression analyses to explore possible reasons for heterogeneity.

RESULTS

We selected a total of 28 studies that were conducted in Australia, the United States, northern Europe, middle Europe, southern Europe, and Asia. The sample size of the SCD group was 6,044. Thirteen studies included a healthy control group (total control cohort of 3,822), whereas the remaining 15 studies were single-arm studies of SCD groups. The APOE e4 allele was associated with SCD (OR 1.12 [1.00-1.25]; p = 0.04). The pooled estimate for APOE e4 carrier prevalence was 32% (95% CI 28-35). Due to the significant heterogeneity in prevalence estimates, we performed stratified and meta-regression analyses and found that age and northern European residency were significantly associated with heterogeneity.

CONCLUSION

The results of this meta-analysis indicate a weak association between APOE e4 and SCD. Age and northern European residency are the critical factors that determine heterogeneity in the APOE e4-associated prevalence of SCD.

Cerebral Glucose Metabolism is Associated with Verbal but not Visual Memory Performance in Community-Dwelling Older Adults

Increasing evidence suggests that Alzheimer's disease (AD) sufferers show region-specific reductions in cerebral glucose metabolism, as measured by [18F]-fluoro-2-deoxyglucose positron emission tomography (18F-FDG PET). We investigated preclinical disease stage by cross-sectionally examining the association between global cognition, verbal and visual memory, and 18F-FDG PET standardized uptake value ratio (SUVR) in 43 healthy control individuals, subsequently focusing on differences between subjective memory complainers and non-memory complainers. The 18F-FDG PET regions of interest investigated include the hippocampus, amygdala, posterior cingulate, superior parietal, entorhinal cortices, frontal cortex, temporal cortex, and inferior parietal region. In the cohort as a whole, verbal logical memory immediate recall was positively associated with 18F-FDG PET SUVR in both the left hippocampus and right amygdala. There were no associations observed between global cognition, delayed recall in logical memory, or visual reproduction and 18F-FDG PET SUVR. Following stratification of the cohort into subjective memory complainers and non-complainers, verbal logical memory immediate recall was positively associated with 18F-FDG PET SUVR in the right amygdala in those with subjective memory complaints. There were no significant associations observed in non-memory complainers between 18F-FDG PET SUVR in regions of interest and cognitive performance. We observed subjective memory complaint-specific associations between 18F-FDG PET SUVR and immediate verbal memory performance in our cohort, however found no associations between delayed recall of verbal memory performance or visual memory performance. It is here argued that the neural mechanisms underlying verbal and visual memory performance may in fact differ in their pathways, and the characteristic reduction of 18F-FDG PET SUVR observed in this and previous studies likely reflects the pathophysiological changes in specific brain regions that occur in preclinical AD.

Screening Ability of Subjective Memory Complaints, Informant-Reports for Cognitive Decline, and Their Combination in Memory Clinic Setting

OBJECTIVE

This study aimed to compare the accuracy of subjective memory complaints, informant-reports for cognitive declines, and their combination for screening cognitive disorders in memory clinic setting.

METHODS

One-hundred thirtytwo cognitively normal (CN), 136 mild cognitive impairment (MCI), and 546 dementia who visited the memory clinic in the Seoul National University Hospital underwent standardized clinical evaluation and comprehensive neuropsychological assessment. The Subjective Memory Complaints Questionnaire (SMCQ) and the Seoul Informant Report Questionnaire for Dementia (SIRQD) were used to assess subjective memory complaints and informant-reports for cognitive declines, respectively.

RESULTS

Both SMCQ and SIRQD showed significant screening ability for MCI, dementia, and overall cognitive disorder (CDall: MCI plus dementia) (screening accuracy: 60.1-94.6%). The combination of SMCQ and SIRQD (SMCQ+SIRQD) was found to have significantly better screening accuracy compared to SMCQ alone for any cognitive disorders. SMCQ+SIRQD also significantly improved screening accuracy of SIRQD alone for MCI and CDall, but not for dementia.

CONCLUSION

Our findings suggest that the combined information of both subjective memory complaints and informant-reports for cognitive declines can improve MCI screening by each individual information, while such combination appears not better than informant-reports in regard of dementia screening.

Association between dementia and vascular disease-associated polymorphisms in a Tunisian population

PURPOSE

Dementia is a multifactorial idiopathic pathology caused by clinical, eDementia is a multifactorial idiopathic pathology caused by clinical, environmental and genetic factors. Hence, its etiology is still unknown. We aimed to evaluate the association between five genetic risk factors for vascular diseases and dementia individually and when gathered in haplotypes.

MATERIALS AND METHOD

We enrolled 200 dementia patients and 300 controls. All subjects were genotyped for vascular diseaseassociated polymorphisms in the genes coding for Apolipoprotein-E (ApoE), angiotensin converting enzyme (ACE) and Paraoxonase-1 (PON1).

RESULTS

The association between dementia risk and all the studied polymorphisms except of PON1-Q192R was found to be significant. Carrying the ApoE e4 allele seems to increase dementia risk by 4.32 fold (p = 0.001). The risk associated with ACE I and PON1-L55M T alleles were lower (2.58 and 2.11 fold, p < 0.001 and p = 0.015, respectively). When combined in haplotypes, these polymorphisms showed a cumulative and synergetic effect. GTICC haplotype appears to be associated with 9-fold dementia risk (p < 0.001), whereas AADTT seems to reduce dementia risk by 80% (p = 0.003).

CONCLUSION

Our results suggest that, ApoE ε4, ACE I and PON1-L55M T alleles are associated with dementia risk whether these polymorphisms were studied separately or gathered in haplotypes. Still, the contribution of each gene to the pathophysiological development of dementia must be more investigated.

The role of depression in the insomnia of people with subjective memory impairment, mild cognitive impairment, and dementia in a community sample of elderly individuals in South Korea

BACKGROUND

This study investigates the relationship between insomnia and cognitive dysfunctions including, subjective memory impairment (SMI), mild cognitive impairment (MCI), and dementia, by considering depression in a community sample of elderly individuals.

METHODS

Data for 1,740 elderly individuals aged 65 years and over were obtained from a nationwide dementia epidemiological study conducted in South Korea. Cognitive functional status was assessed by the Mini-Mental State Examination and the Consortium to Establish a Registry for Alzheimer's Disease Assessment Packet Clinical Assessment Battery. Insomnia was defined as the presence of at least one of the four sleep complaints (difficulty in initiating sleep, difficulty in maintaining sleep, early morning awakening, and non-restorative sleep), accompanied by moderate to severe daytime consequences. Depression was evaluated using the Geriatric Depression Scale.

RESULTS

The prevalence of insomnia in the patients with SMI, MCI, and dementia was found to be 23.2%, 19.6%, and 31.0%, respectively. The patients with SMI, MCI, and dementia were significantly more likely to have insomnia and the four sleep complaints than the normal comparison patients. After adjusting for sociodemographic factors, the significant relationships between cognitive dysfunctional status and insomnia remained. However, after adjusting for sociodemographic factors and depression, no significant relationships with any of the sleep complaints or insomnia remained.

CONCLUSION

Insomnia is a very common complaint in the elderly with SMI, MCI, and dementia. Depression might play an important factor in the relationship between insomnia and cognitive dysfunctional status in the elderly.

The relationship between estimated glomerular filtration rate trajectory and all-cause mortality in type 2 diabetes: the Fremantle Diabetes Study

OBJECTIVE

To investigate the association between estimated GFR (eGFR) and all-cause mortality, including the contribution of temporal eGFR changes, in well-characterised community-based patients with type 2 diabetes.

DESIGN

Longitudinal observational study.

METHODS

Participants from the Fremantle Diabetes Study Phase 1 were assessed between 1993 and 1996 and followed until end-December 2012. Cox proportional hazards modelling was used to assess the relationship between baseline eGFR category (Stage 1-5) and all-cause death, and between eGFR trajectories assigned by semiparametric group-based modelling (GBM) and all-cause death in patients with five post-baseline annual eGFR measurements.

RESULTS

In the full cohort (1296 patients; mean±s.d. age 64.1±11.3years, 48.6% males), 738 (56.9%) died during 12.9±6.1years of follow-up. There was a U-shaped relationship between all-cause death and eGFR category. With Stage 3 (45-59mL/min/1.73m(2)) as reference, the strongest association was for eGFR ≥90mL/min/1.73m(2) (hazard ratio (95% CI) 2.01 (1.52-2.66); P<0.001). GBM identified four linear trajectories ('low', 'medium', 'high', 'high/declining') in 532 patients with serial eGFR measurements. With medium trajectory as reference, eGFR trajectory displaced baseline eGFR category as an independent predictor of death, with low and high/declining trajectories associated with more than double the risk (2.03 (1.30-3.18) and 2.24 (1.31-3.83) respectively, P≤0.003) and associated median reductions in survival of 6.5 and 8.7years respectively.

CONCLUSION

There is a nonlinear relationship between eGFR and death in type 2 diabetes, which is at least partially explained by a sub-group of patients with an initially high but then rapidly declining eGFR.

Genome research in pre-dementia stages of Alzheimer's disease

Genetic characterization of individuals at risk of Alzheimer's disease (AD), i.e. people having amyloid deposits in the brain without symptoms, people suffering from subjective cognitive decline (SCD) or mild cognitive impairment (MCI), has spurred the interests of researchers. However, their pre-dementia genetic profile remains mostly unexplored. In this study, we reviewed the loci related to phenotypes of AD, MCI and SCD from literature and performed the first meta-analyses evaluating the role of apolipoprotein E (APOE) in the risk of conversion from a healthy status to MCI and SCD. For AD dementia risk, an increased number of loci have been identified; to date, 28 genes have been associated with Late Onset AD. In MCI syndrome, APOE is confirmed as a pheno-conversion factor leading from MCI to AD, and clusterin is a promising candidate. Additionally, our meta-analyses revealed APOE as genetic risk factor to convert from a healthy status to MCI [OR = 1.849 (1.587-2.153); P = 2.80  × 10-15] and to a lesser extent from healthy status to SCD [OR = 1.151 (1.015-1.304); P = 0.028]. Thus, we believe that genetic studies in longitudinal SCD and MCI series may provide new therapeutic targets and improve the existing knowledge of AD. This type of studies must be completed on healthy subjects to better understand the natural disease resistance to brain insults and neurodegeneration.

Serum high-density lipoprotein is associated with better cognitive function in a cross-sectional study of aging women

Purpose/Aim of the study: Poor cardiovascular health, including obesity and altered lipid profiles at mid-life, are linked to increased risk of Alzheimer's disease (AD). The biological mechanisms linking cardiovascular health and cognitive function are unclear though are likely to be multifactorial. This study examined the association between various lipoproteins and cognitive functioning in ageing women.

MATERIALS AND METHODS

We investigated the relationship between readily available biomarkers (i.e. serum lipoprotein) and cognitive decline in domains associated with increased risk of AD (e.g. episodic verbal memory performance and subjective memory complaint). We report cross-sectional data investigating the relationship between serum total cholesterol, triglycerides, high-density lipoprotein (HDL-C) and low-density lipoprotein with verbal memory and learning ability in 130 women with and without memory complaints (n = 71 and 59, respectively) drawn from a study investigating cognitively healthy Western Australians (average age 62.5 years old).

RESULTS

After statistical modelling that controlled for the effects of age, depression and apolipoprotein E genotype, HDL-C was significantly associated with better verbal learning and memory performance, specifically short and long delay-free recalls (F = 3.062; p < .05 and F = 3.2670; p < .05, respectively).

CONCLUSION

Our cross-sectional findings suggest that the positive effect of HDL-C on verbal memory may be present much earlier than previously reported and provide further support for the role of HDL-C in healthy brain ageing. Further exploration of the protective effect of HDL-C on cognitive function in ageing is warranted through follow-up, longitudinal studies.

A depressive endophenotype of poorer cognition among cognitively healthy community-dwelling adults: results from the Western Australia memory study

OBJECTIVE

The objective was to evaluate in a cognitively normal population the utility of an endophenotype of the depression-cognition link previously shown to be related to cognitive functioning in mild cognitive impairment and Alzheimer's disease.

METHODS

The data of 460 cognitively normal adults aged 32-92 years (M = 63.5, standard deviation = 9.24) from the Western Australian Memory Study with the Cross-national comparisons of the Cambridge Cognitive Examination-revised (CAMCOG-R) scores and 30-item Geriatric Depression Scale (GDS) scores were analyzed to determine the relationship between the five-item depressive endophenotype (DepE) scale drawn from the GDS and level of performance on a measure of cognitive functioning.

RESULTS

For the entire sample, there was a nonsignificant trend toward a negative relationship between DepE and CAMCOG-R scores. When analyzed for those 65 years and older, there was a significant negative relationship between the two measures (p = 0.001) with DepE scores significantly increasing the risk for performing more poorly on the CAMCOG-R (odds ratio = 1.53). Analysis of data for those 70 years and older showed that DepE was the only predictor significantly related to poorer CAMCOG-R performance (p = 0.001). For the 70 years and older group, DepE scores significantly increased the risk of poorer CAMCOG-R scores (odds ratio = 2.23). Analysis of the entire sample on the basis of ApoEε4 carrier status revealed that DepE scores were significantly negatively related only to ApoEε4 noncarrier regardless of age.

CONCLUSIONS

Elevated DepE scores are associated with poor neuropsychological performance among cognitively normal older adults. Use of the DepE may allow for the identification of a subset of older adults where depression is a primary factor in cognitive decline and who may benefit from antidepressant therapies.

Bone mineral density, adiposity, and cognitive functions

Cognitive decline and dementia due to Alzheimer's disease (AD) have been associated with genetic, lifestyle, and environmental factors. A number of potentially modifiable risk factors should be taken into account when preventive or ameliorative interventions targeting dementia and its preclinical stages are investigated. Bone mineral density (BMD) and body composition are two such potentially modifiable risk factors, and their association with cognitive decline was investigated in this study. 164 participants, aged 34–87 years old (62.78 ± 9.27), were recruited for this longitudinal study and underwent cognitive and clinical examinations at baseline and after 3 years. Blood samples were collected for apolipoprotein E (APOE) genotyping and dual energy x-ray absorptiometry (DXA) was conducted at the same day as cognitive assessment. Using hierarchical regression analysis, we found that BMD and lean body mass, as measured using DXA were significant predictors of episodic memory. Age, gender, APOE status, and premorbid IQ were controlled for. Specifically, the List A learning from California Verbal Learning Test was significantly associated with BMD and lean mass both at baseline and at follow up assessment. Our findings indicate that there is a significant association between BMD and lean body mass and episodic verbal learning. While the involvement of modifiable lifestyle factors in human cognitive function has been examined in different studies, there is a need for further research to understand the potential underlying mechanisms.

APOE ε4 Genotype and the Risk for Subjective Cognitive Impairment in Elderly Persons

The authors compared the risk for subjective cognitive impairment (SCI) between carriers of the apolipoprotein E ε4 (APOE ε4) allele (cases) and APOE ε4 noncarriers (controls). SCI was assessed by a validated self-reported questionnaire. The authors used multivariable logistic regression analyses to compute odds ratios and 95% confidence intervals adjusted for age, sex, education, and marital status. Data were available on 114 participants (83 women; 47 APOE ε4 carriers; mean age, 69 years). The risk for SCI was significantly higher among cases than controls, particularly for those 70 years of age and older. These findings should be considered preliminary until confirmed by a prospective cohort study.

Association between subjective memory complaints and impaired higher-level functional capacity in people aged 60 years or older

OBJECTIVE

We aimed to investigate the association between subjective memory complaints and higher-level functional capacity in either people with long-term care needs or those who require help to maintain functional capacity.

METHODS

We conducted a cross-sectional study among participants aged 60 years or older. We measured subjective memory complaints, higher-level functional capacity, and depressive symptoms, and then estimated odds ratios (ORs) by multiple logistic analysis. Subjective memory complaints were used as the predictor variable, higher-level functional capacity as the outcome variable, and age, depressive symptoms, medical history of diabetes and hypertension, frequency of going out, falling within a year, and body mass index as possible confounders. We assessed higher-level functional capacity using the Tokyo Metropolitan Institute of Gerontology (TMIG) index of competence score ≤5 as a cut-off (which is associated with higher one-year mortality rates).

RESULTS

We conducted analyses using 501 people aged 60 years or older. Among women, subjective memory complaints were associated with impaired higher-level functional capacity after adjustment for age and depressive symptoms (OR=3.36; 95% confidence interval [CI], 1.59-7.08). Among the men, subjective memory complaints were not significantly associated with impaired higher-level functional capacity after adjustment for age and depressive symptoms (OR=1.91; 95% CI, 0.88-4.12).

CONCLUSIONS

Subjective memory complaints among women can indicate impaired higher-level functional capacity and may suggest higher one-year mortality rates.

Subjective cognitive concerns, episodic memory, and the APOE ε4 allele

BACKGROUND

Subjective cognitive concerns may represent a simple method to assess likelihood of memory decline among apolipoprotein E (APOE) ε4 carriers.

METHODS

We examined the relationship of self-reported subjective cognitive concerns, using seven specific cognitive concerns, with memory and memory decline over 6 years among APOE ε4 carriers and non-carriers from the Nurses' Health Study.

RESULTS

In both groups, increasing subjective cognitive concern score predicted worse baseline memory and faster rates of subsequent memory decline, after adjustment for age, education and depression. The relation with baseline memory appeared statistically stronger in APOE ε4 carriers (P-interaction = 0.03). For memory decline, mean differences in slopes of episodic memory (95% CI) for 4 to 7 versus no concern = -0.05 (-0.10, 0.01) standard units in APOE ε4 carriers, and -0.04 (-0.08, -0.01) standard units in non-carriers.

CONCLUSIONS

APOE ε4 carriers with self-assessed cognitive concerns appear to have worse memory, and possibly accelerated memory decline.

Demographic, clinical, and lifestyle correlates of subjective memory complaints in the Australian population

OBJECTIVES

To provide estimates of the prevalence and correlates of subjective memory complaints in older individuals by using population-based Australian data.

DESIGN

2007 National Survey of Mental Health and Well-Being.

SETTING

Australia.

PARTICIPANTS

1,905 community-dwelling participants aged 65-85 years.

MEASUREMENTS

Subjective memory complaints were assessed by using two questions reflecting: (1) poorer memory compared with others of the same age ("worse memory"); and (2) a decline in memory performance over the previous 5 years ("declining memory"). Twelve-month and lifetime diagnoses were derived from structured diagnostic interviews. Other correlates investigated included chronic physical conditions, lifestyle factors, and service use. Analyses adjusted for scores on the Mini-Mental State Examination.

RESULTS

Subjective memory complaints were reported by one-third (33.5%) of respondents. Those who reported either complaint were more likely to report psychological distress, poor functioning, service use, and negative self-assessed mental and physical health. "Declining memory" over the past 5 years was also related to an increase in the rates of psychiatric disorders. After adjusting for other variables of interest, associations were established between subjective memory complaints and psychological distress, poor functioning, negative self-assessed mental health, and alcohol use disorders. Except for the association between "declining memory" and anxiety and depression, these associations remained significant after excluding those with scores <27 on the Mini-Mental State Examination.

CONCLUSIONS

Subjective memory complaints were associated with several negative clinical characteristics that should be considered when interpreting these complaints. Subjective memory complaints may be valid indicators of psychopathology and the need for clinical assessment.

Cognitive impairment in older patients with breast cancer before systemic therapy: is there an interaction between cancer and comorbidity?

PURPOSE

To determine if older patients with breast cancer have cognitive impairment before systemic therapy.

PATIENTS AND METHODS

Participants were patients with newly diagnosed nonmetastatic breast cancer and matched friend or community controls age > 60 years without prior systemic treatment, dementia, or neurologic disease. Participants completed surveys and a 55-minute battery of 17 neuropsychological tests. Biospecimens were obtained for APOE genotyping, and clinical data were abstracted. Neuropsychological test scores were standardized using control means and standard deviations (SDs) and grouped into five domain z scores. Cognitive impairment was defined as any domain z score two SDs below or ≥ two z scores 1.5 SDs below the control mean. Multivariable analyses evaluated pretreatment differences considering age, race, education, and site; comparisons between patient cases also controlled for surgery.

RESULTS

The 164 patient cases and 182 controls had similar neuropsychological domain scores. However, among patient cases, those with stage II to III cancers had lower executive function compared with those with stage 0 to I disease, after adjustment (P = .05). The odds of impairment were significantly higher among older, nonwhite, less educated women and those with greater comorbidity, after adjustment. Patient case or control status, anxiety, depression, fatigue, and surgery were not associated with impairment. However, there was an interaction between comorbidity and patient case or control status; comorbidity was strongly associated with impairment among patient cases (adjusted odds ratio, 8.77; 95% CI, 2.06 to 37.4; P = .003) but not among controls (P = .97). Only diabetes and cardiovascular disease were associated with impairment among patient cases.

CONCLUSION

There were no overall differences between patients with breast cancer and controls before systemic treatment, but there may be pretreatment cognitive impairment within subgroups of patient cases with greater tumor or comorbidity burden.

A conceptual framework for research on subjective cognitive decline in preclinical Alzheimer's disease

There is increasing evidence that subjective cognitive decline (SCD) in individuals with unimpaired performance on cognitive tests may represent the first symptomatic manifestation of Alzheimer's disease (AD). The research on SCD in early AD, however, is limited by the absence of common standards. The working group of the Subjective Cognitive Decline Initiative (SCD-I) addressed this deficiency by reaching consensus on terminology and on a conceptual framework for research on SCD in AD. In this publication, research criteria for SCD in pre-mild cognitive impairment (MCI) are presented. In addition, a list of core features proposed for reporting in SCD studies is provided, which will enable comparability of research across different settings. Finally, a set of features is presented, which in accordance with current knowledge, increases the likelihood of the presence of preclinical AD in individuals with SCD. This list is referred to as SCD plus.

Cognitive effects of cancer and its treatments at the intersection of aging: what do we know; what do we need to know?

There is a fairly consistent, albeit non-universal body of research documenting cognitive declines after cancer and its treatments. While few of these studies have included subjects aged 65 years and older, it is logical to expect that older patients are at risk of cognitive decline. Here, we use breast cancer as an exemplar disease for inquiry into the intersection of aging and cognitive effects of cancer and its therapies. There are a striking number of common underlying potential biological risks and pathways for the development of cancer, cancer-related cognitive declines, and aging processes, including the development of a frail phenotype. Candidate shared pathways include changes in hormonal milieu, inflammation, oxidative stress, DNA damage and compromised DNA repair, genetic susceptibility, decreased brain blood flow or disruption of the blood-brain barrier, direct neurotoxicity, decreased telomere length, and cell senescence. There also are similar structure and functional changes seen in brain imaging studies of cancer patients and those seen with "normal" aging and Alzheimer's disease. Disentangling the role of these overlapping processes is difficult since they require aged animal models and large samples of older human subjects. From what we do know, frailty and its low cognitive reserve seem to be a clinically useful marker of risk for cognitive decline after cancer and its treatments. This and other results from this review suggest the value of geriatric assessments to identify older patients at the highest risk of cognitive decline. Further research is needed to understand the interactions between aging, genetic predisposition, lifestyle factors, and frailty phenotypes to best identify the subgroups of older patients at greatest risk for decline and to develop behavioral and pharmacological interventions targeting this group. We recommend that basic science and population trials be developed specifically for older hosts with intermediate endpoints of relevance to this group, including cognitive function and trajectories of frailty. Clinicians and their older patients can advance the field by active encouragement of and participation in research designed to improve the care and outcomes of the growing population of older cancer patients.

Self-reported cognitive decline on the informant questionnaire on cognitive decline in the elderly is associated with dementia, instrumental activities of daily living and depression but not longitudinal cognitive change

BACKGROUND/AIM

A subjective history of cognitive decline is integral to dementia screening, yet there are few data on the accuracy of retrospective self-reports. We prospectively examined the longitudinal predictors of self-reported decline, including rate of cognitive change, clinical diagnosis, depressive symptoms and personality.

METHODS

We used a large (n = 2,551) community-dwelling sample of older adults (60-64 years at baseline) and tracked their cognitive functioning over 3 waves across a period of 8 years. Individual rates of change in multiple domains of cognition, incident dementia and mild cognitive disorders, apolipoprotein E (APOE) ε4 genotype, level of education, depressive symptoms and personality were examined as predictors of wave 3 retrospective self-reported decline as measured by the Informant Questionnaire on Cognitive Decline in the Elderly.

RESULTS

The rate of cognitive decline did not predict subjective decline. Significant predictors of self-reported decline included dementia diagnosis, problems with instrumental activities of daily living, depression and neuroticism at the time of self-report, as well as the presence of an APOE ε4 allele.

CONCLUSIONS

In this relatively young cohort, retrospective self-report of cognitive decline does not reflect objective deterioration in cognition over the time period in question, but it may identify individuals in the initial stages of dementia and those with elevated psychological and genotypic risk factors for the development of dementia.

The Cognitive Change in Women study (CCW): informant ratings of cognitive change but not self-ratings are associated with neuropsychological performance over 3 years

The value of self-reported memory complaints for identifying or predicting future cognitive decline or dementia is controversial, but observations from a third party, or "informant," may prove more useful. The relationship between Informant and Self-ratings of cognitive status and neuropsychological test scores was examined in a cohort of 384 nondemented, community-dwelling women, aged 60 years and older, participating in a single-site Women's Health Initiative ancillary study. Each participant and her respective informant separately completed the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE). Participants also underwent neuropsychological testing and responded to questionnaires on depression and functioning in complex activities of daily living. All neuropsychological test scores were significantly correlated (P values <0.05 to <0.01) with IQCODE ratings whereas Self-ratings overestimated cognitive functioning in some domains. Furthermore, the Self and Informant ratings were both positively correlated with depression and negatively correlated with participants' activity level. Therefore, informant judgments of functional abilities are robust predictors of cognitive status in high functioning nondemented women. These results suggest that informants may be sensitive to changes that are not clinically significant but that may represent an incipient trend for decline.

Interaction effects of subjective memory impairment and ApoE4 genotype on episodic memory and hippocampal volume

BACKGROUND

The apolipoprotein E4 allele (ApoE4) is an established genetic risk factor for Alzheimer's disease (AD). However, its effects on cognitive performance and brain structure in healthy individuals are complex. We investigated the effect of ApoE4 on cognitive performance and medial temporal lobe volumetric measures in cognitively unimpaired young elderly with and without subjective memory impairment (SMI), which is an at-risk condition for dementia.MethodAltogether, 40 individuals with SMI and 62 without were tested on episodic memory and on tasks of speed and executive function. All participants were ApoE genotyped. 21 subjects with SMI and 47 without received additional structural magnetic resonance imaging. Volumetric measures of the hippocampus, the entorhinal cortex and the amygdala were obtained manually.

RESULTS

In the SMI group, ApoE4 carriers performed worse on the episodic memory (p=0.049) and showed smaller left hippocampal volumes (p=0.030). In the individuals without SMI, the ApoE4 carriers performed better on episodic memory (p=0.018) and had larger right hippocampal volumes (p=0.039). The interaction of group (SMI/no SMI) and ApoE genotype was significant for episodic memory (p=0.005) and right and left hippocampal volumes (p=0.042; p=0.035). There were no within-group differences or interaction effects on speed and executive function composite measures or other volumetric measures.

CONCLUSIONS

The negative effect of ApoE4 on episodic memory and hippocampal volume in SMI supports SMI as a prodromal condition of AD. The positive effects of ApoE4 in subjects without SMI adds to a number of reports on positive ApoE4 effects in young and very old individuals.

Apolipoprotein E genotype and mortality in Southern European and Anglo-Celt patients with type 2 diabetes: the Fremantle Diabetes Study

OBJECTIVE

To determine whether cardiac and all-cause mortality are lower in Southern European (SE) patients than in Anglo-Celt (AC) patients with type 2 diabetes in an urban Australian setting, and, if so, whether ethnicity-specific differences in apolipoprotein E (APOE) genotypes are contributory.

DESIGN

Longitudinal observational cohort study.

METHODS

We analysed detailed data from 1057 patients from the community-based Fremantle Diabetes Study, 238 were of an SE migrant background and 819 of AC ethnicity. Cox proportional hazards modelling was used to identify independent predictors of cardiac and all-cause mortality.

RESULTS

During 9.8±3.5 years of follow-up, 411 (38.9%) participants died, 161 (39.2%) from cardiac causes. Significant positive baseline independent predictors of cardiac death were age, male gender, coronary heart disease, cerebrovascular disease, peripheral arterial disease, retinopathy and peripheral neuropathy (P≤0.004), while maternal history of diabetes was protective (P=0.014). After adjusting for these variables, APOE4 carriage was predictive (hazard ratio (95% confidence interval) 1.61 (1.01-2.58); P=0.048). SE ethnicity did not add significantly to the model either as a single variable or as an interaction term with APOE4 carriage (P≥0.86). Significant independent predictors of all-cause mortality were age, male gender, smoking, coronary heart disease, cerebrovascular disease, peripheral arterial disease, retinopathy, peripheral neuropathy and microalbuminuria (P≤0.047), while overweight/obesity, lipid-lowering therapy and recent exercise were protective (P≤0.008). APOE4 carriage, SE ethnicity and their interaction did not add to the model (P≥0.32).

CONCLUSIONS

SE ethnicity does not confer an independent survival advantage in community-based Australian type 2 diabetic patients, but APOE4 carriers are at higher risk of cardiac death.

Differential levels of apolipoprotein E and butyrylcholinesterase show strong association with pathological signs of Alzheimer's disease in the brain in vivo

Recently, we reported that 3 of the known risk factors of Alzheimer's disease (AD), i.e., advanced age, apolipoprotein E (ApoE) ε4, and female gender, are associated with differential levels of ApoE proteins and butyrylcholinesterase (BuChE) in the cerebrospinal fluid (CSF) of AD patients. The ApoE ε4 allele and certain BuChE polymorphisms synergistically affect the conversion rate of mild cognitive impairment (MCI) to AD. Here, we investigated interrelationships between ApoE and BuChE levels, and pathological markers of AD in vivo. CSF from patients with probable AD, assessed for cerebral glucose metabolism (CMRglc; n = 50) and Pittsburgh compound B (PIB) retention (β-amyloid [Aβ] load, n = 29) by positron emission tomography (PET), was used for measurement of BuChE, ApoE, Aβ, tau, phosphorylated tau (P-tau) and interleukin-1β (IL-1β) levels. Levels of ApoE and BuChE strongly correlated with CMRglc (fluorodeoxyglucose [FDG]-PET, r = 0.54, p < 0.0001, n = 50), cerebral Aβ load (PIB retention, r = 0.73, p < 0.0001, n = 29), and CSF P-tau (r = 0.73, p < 0.0001, n = 33). High ApoE protein was tied to low CMRglc and high PIB retention and P-tau. BuChE levels had opposite relationships. Other CSF covariates were levels of interleukin-1β and Aβ(42) peptide. The pattern of the patients' cognitive Z-scores strongly supported these observations. High ApoE protein was also linked to changes in 3 of the biodynamic properties of BuChE. In vitro analysis indicated that high ApoE protein levels were related to an increased pool of dormant BuChE molecules with an abnormally high intrinsic catalytic rate in CSF, which was "turned on" by excess Aβ peptides. The findings suggest that abnormally high levels of ApoE may play a causative role in the pathological events of AD, particularly those involving the early cholinergic deficit in the AD brain, through modulation of cholinesterases activities, hence disturbing the acetylcholine-dependent activity of neurons and nonexcitable cells such as glial cells.

The APOE-491 A/T promoter polymorphism effect on cognitive profile of Alzheimer's patients

Alzheimer's Disease (AD) is a neurodegenerative disorder with a complex aetiology displayed by multiple pathogenic factors. The APOE varepsilon4 allele represents the only established genetic risk factor for sporadic AD; in addition, previous findings on three single nucleotide polymorphisms (SNPs) located on the APOE promoter region, have led to a growing interest in their potential role in AD pathogenesis. The -491 A/T promoter polymorphism has been the one most frequently shown to be associated with AD, as it influences the APOE coding region transcription. The aim of this study was to evaluate the possible effect of the -491 A/T polymorphism on the cognitive profile of sporadic AD patients with a disease severity ranging from mild to moderate. Our results showed that patients carrying the -491 AA genotype had poorer cognitive performances than the -491 AT ones, statistically significant in demanding tests of visual attention, especially for the late-onset AD (LOAD). No further differences on cognitive profile were observed when stratifying AA and AT patients according to their APOE genotype. These results suggest a possible functional effect of the -491 A/T promoter on the neuropsychological performances of AD. This role seems to be independent of APOE genotype. In fact the effect of -491 A/T occurs predominantly on attention while the APOE varepsilon4 allele mainly affects memory performances. According to the biological effect exerted on APOE transcription, the -491 A/T polymorphism could be considered a disease modifier more than a risk factor for sporadic AD.

Functional characterization of three single-nucleotide polymorphisms present in the human APOE promoter sequence: Differential effects in neuronal cells and on DNA-protein interactions

Variations in levels of apolipoprotein E (ApoE) have been tied to the risk and progression of Alzheimer's disease (AD). Our group has previously compared and contrasted the promoters of the mouse and human ApoE gene (APOE) promoter sequences and found notable similarities and significant differences that suggest the importance of the APOE promoter's role in the human disease. We examine here three specific single-nucleotide polymorphisms within the human APOE promoter region, specifically at -491 (A/T), -427 (T/C), and at -219 (G/T) upstream from the +1 transcription start site. The -219 and -491 polymorphic variations have significant association with instance of AD, and -491AA has significant risk even when stratified for the APOEepsilon4 allele. We also show significant effects on reporter gene expression in neuronal cell cultures, and, notably, these effects are modified by species origin of the cells. The -491 and -219 polymorphisms may have an interactive effect in addition to any independent activity. DNA-protein interactions differ between each polymorphic state. We propose SP1 and GATA as candidates for regulatory control of the -491 and -219 polymorphic sites. This work's significance lies in drawing connection among APOE promoter polymorphisms' associations with AD to functional promoter activity differences and specific changes in DNA-protein interactions in cell culture-based assays. Taken together, these results suggest that APOE expression levels are a risk factor for AD irrespective of APOEepsilon4 allele status.

Clearance mechanisms of Alzheimer's amyloid-beta peptide: implications for therapeutic design and diagnostic tests

Currently, the 'amyloid hypothesis' is the most widely accepted explanation for the pathogenesis of Alzheimer's disease (AD). According to this hypothesis, altered metabolism of the amyloid-beta (Abeta) peptide is central to the pathological cascade involved in the pathogenesis of AD. Although Abeta is produced by almost every cell in the body, a physiological function for the peptide has not been determined, and the pathways by which Abeta leads to cognitive dysfunction and cell death are unclear. Numerous therapeutic approaches that target the production, toxicity and removal of Abeta are being developed worldwide. Although therapeutic treatment for AD may be imminent, the value and effectiveness of such treatment are largely dependent on early diagnosis of the disease. This review summarizes current knowledge of Abeta clearance, transport and degradation, and evaluates the use of such information in the development of diagnostic tools. The conflicting results of plasma Abeta ELISAs are discussed, as are the more promising results of Abeta imaging by positron emission tomography. Current knowledge of Abeta-binding proteins and Abeta-degrading enzymes is analysed in the context of a potential therapy for AD. Transport across the blood-brain barrier by the receptor for advanced glycation end products and efflux via the multi-ligand lipoprotein receptor LRP-1 is also reviewed. Enhancing clearance and degradation of Abeta remains an attractive therapeutic strategy, and improved understanding of Abeta clearance may lead to advances in diagnostics and interventions designed to prevent or delay the onset of AD.

Memory complaints in mild cognitive impairment, worried well, and semantic dementia patients

Complaints related to memory are characteristic of normal ageing, affective disorders, and are a cardinal feature of amnestic mild cognitive impairment (aMCI), the proposed prodrome to Alzheimer disease proper. The aim of this study was to investigate the profile of subjective memory complaints in different cognitive syndromes. Subjective memory was assessed using the Cambridge Memory Complaints Questionnaire consisting of 20 questions about everyday aspects of memory. This was completed by 22 "worried well" (WW), 85 aMCI, and 40 semantic dementia (SD) patients at first presentation to a memory clinic. All patients were followed up for 2 years. A principal component factor analysis revealed 5 principal factors pertaining to working, episodic, topographical, and semantic memory. All factors, except topographical memory, reliably differentiated SD patients from other groups, with aMCI and WW patients complaining significantly more about working and episodic memory, and SD patients complaining significantly more about semantic memory. WW and aMCI patients, however, could not be differentiated, even those aMCI patients who progressed to dementia. Memory complaints are strikingly similar to the description of typical core deficits in SD patients. The sole reliance on memory complaints for insight into memory functioning and diagnosing aMCI is problematic.

Subjective memory complaints and clinical characteristics in elderly Koreans: A questionnaire survey

OBJECTIVES

The overall objectives of the Ajou-Bundang Study for the Elderly (AB study) were to describe the current geriatric diseases and health behaviors, and to improve the visiting health service in South Korea. The particular objectives of the current study were to describe the AB study and to investigate the associations between subjective memory complaints (SMCs) and objective cognitive function, to assess the clinical characteristics of SMCs, and to measure possible differences between elderly people with and without cognitive dysfunction.

METHODS

A cross-sectional study of a sample of people from the AB study was constructed to study the association between SMCs and demographic variables. SMCs, cognitive function, and demographic characteristics were ascertained. A total of 9,477 subjects aged 65 years or over were recruited from the residents of Bundang, Korea.

RESULTS

SMCs were reported by 57.3% of the study participants. SMCs were correlated with advanced age and with being female. Further analyses of cognitive functions revealed that associated factor profiles differed between the participants with and without cognitive dysfunction.

CONCLUSIONS

These results show that age is associated with SMCs, irrespective of the level of cognitive function. Longitudinal SMC studies should be undertaken to investigate potentially associated clinical parameters.

Important differences between human and mouse APOE gene promoters: limitation of mouse APOE model in studying Alzheimer's disease

Apolipoprotein E (ApoE), encoded by the apolipoprotein E gene (APOE), plays an important role in the pathogenesis of Alzheimer's disease (AD). The APOE epsilon4 variant is strongly associated with AD. APOE promoter polymorphisms have also been reported to associate with higher AD risk. Mouse models of APOE expression have long been used to study the pathogenesis of AD. Elucidating the role of the APOE gene in AD requires understanding of how its regulation differs between mouse and human APOE genes, and how the differences influence AD risk. We compared the structure and function of both the human APOE gene promoter (hAPOEP) and mouse APOE gene promoter (mAPOEP) regions. Homology is less than 40% at 180 bp or more upstream of the two species' transcription start site (TSS, +1). Functional analysis revealed both similarities and important differences between the two sequences, significantly affected by human versus rodent cell line origin. We likewise probed nuclear extracts from several cell lines of different origins (astrocytic, glial, and neuronal) and mouse brain with specific hAPOEP and mAPOEP fragments. Each fragment shared DNA-protein interactions with the other but, notably, also bound distinct factors, demonstrated by gel shift and southwestern analyses. We determined possible identities for these distinct factors. These results suggest that regulation of mouse and human APOE genes may be sufficiently unique to justify the use of both the human APOE promoter sequence in transgenic rodent models and non-rodent AD models for studying factors involved in AD pathogenesis.

Candidate mechanisms for chemotherapy-induced cognitive changes

The mechanism(s) for chemotherapy-induced cognitive changes are largely unknown; however, several candidate mechanisms have been identified. We suggest that shared genetic risk factors for the development of cancer and cognitive problems, including low-efficiency efflux pumps, deficits in DNA-repair mechanisms and/or a deregulated immune response, coupled with the effect of chemotherapy on these systems, might contribute to cognitive decline in patients after chemotherapy. Furthermore, the genetically modulated reduction of capacity for neural repair and neurotransmitter activity, as well as reduced antioxidant capacity associated with treatment-induced reduction in oestrogen and testosterone levels, might interact with these mechanisms and/or have independent effects on cognitive function.

Volume reduction of the entorhinal cortex in subjective memory impairment

To examine the biological basis of subjective memory impairment (SMI), defined as the feeling of memory worsening with normal memory performance, we measured the volume of the entorhinal cortex (EC) and the hippocampus in SMI subjects, patients with mild cognitive impairment (MCI), patients with Alzheimer's disease (AD) and healthy controls (CO). Compared with controls, the EC was smaller in the SMI group (left: p=0.060; right: p=0.045) and in the other two groups in the following order: CO>SMI>MCI>AD. The same sequence was observed with regard to hippocampal volumes, but the volume reduction of the left hippocampus in the SMI group only reached a trend towards significance (p=0.072) and the right was not significantly smaller compared with controls (p=0.37). Compared with controls the average (left/right) volume reduction of the EC was 18% (SMI), 26% (MCI) and 44% (AD). The mean volume reduction of the hippocampus was 6% (SMI), 16% (MCI) and 19% (AD). Our results mirror the temporal sequence of neurodegeneration in AD and support the concept of SMI as the first clinical manifestation of dementia.

Apolipoprotein E4 genotype is not associated with short-term cognition deficits during alcohol withdrawal

Aim of this prospective study was to investigate a possible association between the apolipoprotein E4 (ApoE4) genotype and clinically well-known cognition deficits during alcohol withdrawal. We examined 172 patients with alcohol dependence (137 men, 35 women) during withdrawal treatment. The ApoE genotype was determined in all patients using polymerase chain reaction. Cognitive function was assessed applying the c.I.-Test on day 0 (admission) and on day 7 of withdrawal treatment. Using Pearson's chi2 test we found no significant association between the ApoE4 genotype and cognition deficits for both dates (day 0: p=.463; day 7: p=.760). Moreover, multivariate logistic regression analyses revealed no significant association between presence of the ApoE4 allele and cognitive dysfunction. Even though ApoE4 plays an important role in alcoholism-related brain atrophy and cognition deficits in demented as well as in nondemented healthy elderly people, this study provides no evidence for an association with short-term cognition deficits during alcohol withdrawal.

Cognitive effects of cytotoxic cancer chemotherapy: predisposing risk factors and potential treatments

Increasing evidence suggests that systemic cancer chemotherapy can have significant long-term effects on cognition, particularly on verbal learning, memory, attention, and speed of information processing. These deficits can be a source of significant distress to survivors. There is much less known about the mechanisms, predisposing vulnerabilities, and treatment of these deficits. We will summarize current knowledge of chemotherapy-associated cognitive deficits. Emerging theories about the role of selected genetic polymorphisms in heightening the vulnerability to chemotherapy-induced cognitive decline will be described.