Longitudinal changes in cognition and behavior in asymptomatic carriers of the APOE e4 allele

Increasing CSF phospho-tau levels during cognitive decline and progression to dementia

BACKGROUND

Little is known about longitudinal changes of cerebrospinal fluid (CSF) biomarkers during cognitive decline in neurodegenerative disease progression.

OBJECTIVE

To investigate longitudinal changes in CSF biomarkers--total-tau (T-tau), phospho-tau (P-tau) and beta-amyloid (Abeta42)--during cognitive decline.

METHODS

Forty memory clinic patients (47.5% females), aged 61.3+/-7.6 (S.D.) years, non-demented at baseline, underwent lumbar puncture and neuropsychological testing at two occasions. Baseline mean MMSE-score was 28.3+/-1.8. Patients were divided into three groups based on baseline memory functioning; severely impaired (SIM), moderately impaired (MIM) and no impairment (NIM).

RESULTS

There was a significant increase in P-tau in the SIM-group during follow-up, while P-tau in MIM and NIM did not change. Eighty-three percent of the SIM-patients converted to dementia (80% AD), while most MIM- and NIM-patients remained non-demented. T-tau- and Abeta42-levels did not change in any of the memory groups during follow-up.

CONCLUSION

Increasing P-tau levels during cognitive decline and conversion to dementia suggest that P-tau may be useful as a longitudinal marker of the neurodegenerative process.

Brain tumor epidemiology: consensus from the Brain Tumor Epidemiology Consortium

Epidemiologists in the Brain Tumor Epidemiology Consortium (BTEC) have prioritized areas for further research. Although many risk factors have been examined over the past several decades, there are few consistent findings, possibly because of small sample sizes in individual studies and differences between studies in patients, tumor types, and methods of classification. Individual studies generally have lacked samples of sufficient size to examine interactions. A major priority based on available evidence and technologies includes expanding research in genetics and molecular epidemiology of brain tumors. BTEC has taken an active role in promoting understudied groups, such as pediatric brain tumors; the etiology of rare glioma subtypes, such as oligodendroglioma; and meningioma, which, although it is not uncommon, has only recently been registered systematically in the United States. There also is a pressing need for more researchers, especially junior investigators, to study brain tumor epidemiology. However, relatively poor funding for brain tumor research has made it difficult to encourage careers in this area. In this report, BTEC epidemiologists reviewed the group's consensus on the current state of scientific findings, and they present a consensus on research priorities to identify which important areas the science should move to address.

Apolipoprotein E epsilon4 influences on episodic recall and brain structures in aging pilots

The apolipoprotein (APOE) epsilon4 allele is associated with cognitive deficits and hippocampal atrophy in nondemented middle-aged and older adults. It is not known to what extent this genetic risk factor for Alzheimer's disease (AD) impacts performance in late middle-aged and older workers in cognitively demanding occupations. This cross-sectional analysis examines brain-cognitive-genetic relationships in actively flying general aviation pilots, half of whom are APOE epsilon4 carriers. Fifty pilots were studied with structural MRI and memory tasks. Average visual paired associate memory recall performance was lower in APOE epsilon4 carriers than non-carriers. Memory performance correlated positively with hippocampal volume, but no structural differences were found in hippocampal or frontal volumes with respect to APOE epsilon4 allele. These results were evident in healthy professionals without any presenting memory problems and without selection for a family history of AD. These findings point to basic memory testing as a sensitive tool for detecting APOE epsilon4-related influences on memory in aging workers.

Effect of parental family history of Alzheimer's disease on serial position profiles

BACKGROUND

An exaggerated recency effect (ie, disproportionate recall of last-presented items) has been consistently observed in the word list learning of patients with Alzheimer's disease (AD). Our study sought to determine whether there were similar alterations in serial position learning among asymptomatic persons at risk for AD as a result of parental family history.

METHODS

Subjects included 623 asymptomatic middle-aged children of patients with AD (median, 53 years) and 157 control participants whose parents survived to at least age 70 without AD or other memory disorders. All participants were administered the Rey Auditory Verbal Learning Test, which requires learning and recall of 15 unrelated nouns.

RESULTS

There was no significant difference in total words recalled between the AD children and control groups. However, compared with controls, AD children exhibited a significantly greater tendency to recall words from the end (recency) versus beginning (primacy) of the list. Serial position effects were unrelated to apolipoprotein allele epsilon 4 or depressive symptoms.

CONCLUSIONS

Asymptomatic persons at risk for AD by virtue of family history do not show a difference in total words recalled compared with controls, but they exhibit a distinctly different serial position curve, suggesting greater reliance on immediate as opposed to episodic memory. This is the same serial position pattern observed in mild AD, seen here in reduced severity. Longitudinal follow-up is planned to determine whether changes in serial position patterns are a meaningful marker for preclinical detection of AD.

Acute and long-term associations between ApoE genetic polymorphism, cortisol levels, and declarative memory performance in older adults

CONTEXT

For the past two decades, researchers have shown that elevated levels of circulating stress hormones may negatively impact cognitive performance in older adults. As well, genetic polymorphism of the apolipoprotein E gene (APOE) has been found to contribute to impairment in cognitive performance in old age. To date, only one study has reported a relationship between APOE status and cortisol levels, however the relationship was only found to be significant in dementia patients, with a trend observed in healthy controls.

OBJECTIVE

The goal of the present investigation was to examine the acute and long-term relationship between APOE status, cortisol secretion, and declarative memory performance in older adults.

DESIGN

Two sample cohorts were assessed. In the first cohort, 24-h basal serum cortisol levels were obtained once a year over eight years to assess changes in basal cortisol levels over time. Declarative memory was also obtained in this group at three time-points over five years. In the second cohort, basal and stress-induced cortisol levels as well as basal declarative memory was tested.

RESULTS

In the first cohort, E4 carriers were found to secrete higher serum cortisol levels than non-E4 carriers during the first 24-h visit (p=0.04) to the laboratory. However, this group difference did not remain over subsequent years. Furthermore, declarative memory performance over years did not significantly differ according to APOE status. In the second cohort, no significant group differences were found for basal or reactive cortisol levels (ps>0.05), and no group difference was found for acute declarative memory performance.

CONCLUSION

The findings in this study suggest minimal to no significant effect of APOE status on cortisol secretion or declarative memory in non-demented older adults.

Neuropsychological contributions to the early identification of Alzheimer's disease

A wealth of evidence demonstrates that a prodromal period of Alzheimer's disease (AD) exists for some years prior to the appearance of significant cognitive and functional declines required for the clinical diagnosis. This prodromal period of decline is characterized by a number of different neuropsychological and brain changes, and reliable identification of individuals prior to the development of significant clinical symptoms remains a top priority of research. In this review we provide an overview of those neuropsychological changes. In particular, we examine specific domains of cognition that appear to be negatively affected during the prodromal period of AD, and we review newer analytic strategies designed to examine cognitive asymmetries or discrepancies between higher-order cognitive functions versus fundamental skills. Finally, we provide a critical examination of the clinical concept of Mild Cognitive Impairment and offer suggestions for an increased focus on the impact of cerebrovascular disease (CVD) and CVD risk during the prodromal period of AD.

Neuropsychological contributions to the early identification of Alzheimer's disease

A wealth of evidence demonstrates that a prodromal period of Alzheimer's disease (AD) exists for some years prior to the appearance of significant cognitive and functional declines required for the clinical diagnosis. This prodromal period of decline is characterized by a number of different neuropsychological and brain changes, and reliable identification of individuals prior to the development of significant clinical symptoms remains a top priority of research. In this review we provide an overview of those neuropsychological changes. In particular, we examine specific domains of cognition that appear to be negatively affected during the prodromal period of AD, and we review newer analytic strategies designed to examine cognitive asymmetries or discrepancies between higher-order cognitive functions versus fundamental skills. Finally, we provide a critical examination of the clinical concept of Mild Cognitive Impairment and offer suggestions for an increased focus on the impact of cerebrovascular disease (CVD) and CVD risk during the prodromal period of AD.

Apolipoprotein E epsilon4, Alzheimer's disease, and cognitive performance in elderly Mexican Mestizos

OBJECTIVES

To determine the relationship between apolipoprotein E (APOE) epsilon4 and Alzheimer's disease (AD) in the Mexican Mestizo population, as well as its effects on the cognitive profile of AD and elderly Mestizos without dementia.

DESIGN

Cross-sectional analysis of a cohort study.

SETTING

Evaluations were conducted at the geriatrics clinic of an academic medical hospital in Mexico City.

PARTICIPANTS

Forty-nine elderly subjects with AD and 141 controls selected from a representative sample of Mexican Mestizos aged 65 to 96 who participated in the Prevalence Survey of Dementia in the Mexico City Elderly Population cohort.

MEASUREMENTS

All subjects underwent APOE genotypification and a comprehensive clinical and neuropsychological evaluation.

RESULTS

There were no significant differences in epsilon3 and epsilon4 frequencies between the subjects with and without AD and a tendency toward higher epsilon4 and lower epsilon3 allele frequencies in subjects aged 75 and older. No association was found between APOE epsilon4 and the presence of AD. The age-, sex-, and education-adjusted risk for AD associated with at least one epsilon4 allele was 1.01 (95% confidence interval=0.45-2.23). Performance on a long-term visual memory test was significantly worse in APOE epsilon4 carriers than in APOE epsilon3 carriers only in the group with AD.

CONCLUSION

APOE epsilon4 did not increase the risk for AD in this Mexican Mestizo elderly urban population sample, although the presence of this allele seems to modify its clinical expression.

Children of persons with Alzheimer disease: what does the future hold?

Children of persons with Alzheimer disease (AD), as a group, face an increased risk of developing AD. Many of them, throughout their adult lives, seek input on how to reduce their chances of one day suffering their parent's fate. We examine the state of knowledge with respect to risk and protective factors for AD and recommend a research agenda with special emphasis on AD offspring.

Apolipoprotein E affects both myelin breakdown and cognition: implications for age-related trajectories of decline into dementia

BACKGROUND

Age-related myelin breakdown is most evident in later-myelinating white matter (LMwm) brain regions. This process might degrade cognitive processing speed (CPS) underlying age-related cognitive decline and the predominance of age as a risk factor for Alzheimer's disease (AD). Apolipoprotein E (ApoE) 4 allele is the second most important AD risk factor. We tested the hypothesis that ApoE4 accelerates age-related slowing in CPS through the process of myelin breakdown.

METHODS

Calculated transverse relaxation rates (R(2)), an indirect magnetic resonance imaging measure of myelin breakdown in LMwm, and measures of CPS were obtained in 22 ApoE4+ and 80 ApoE4-, healthy "younger-old" individuals. To assess specificity, contrasting early-myelinating white matter region and memory task were also examined.

RESULTS

The CPS versus LMwm R(2) remained significant in the ApoE4+ group even after age was statistically adjusted (r = .65, p = .001) and differed from the correlation observed in the ApoE4- group (Fisher's z test = 3.22, p < .002). No significant associations were observed with the contrast region and memory task in either ApoE subgroup.

CONCLUSIONS

A specific association between CPS and myelin breakdown in LMwm exists in asymptomatic "younger-old" individuals at increased genetic risk for AD. Although inferences of change over time and causality are limited by the cross-sectional study design, this finding lends support to the hypotheses that myelin breakdown underlies age-related slowing in CPS and that by altering the trajectory of myelin breakdown, ApoE alleles shift the age at onset of cognitive decline. Combined use of biomarkers and CPS measures might be useful in developing and targeting primary prevention treatments for AD.

APOE status and its association to learning and memory performance in middle aged and older Norwegians seeking assessment for memory deficits

BACKGROUND

We examined the hypothesis that deficits in learning, memory, and other cognitive functions are associated with the epsilon4 allele of the Apolipoprotein E (APOE) gene in a non-demented sample with memory complaints recruited from a population with a high prevalence of this allele.

METHODS

The study group comprised 70 consecutively referred patients aged 50-75 seeking assessment due to memory complaints. They were screened for dementia, for neurological and psychiatric disease, and for cerebral infarction using Magnet Resonance Imaging (MRI). Participants were classified as non-demented based on clinical evaluation and results on cognitive tests.

RESULTS

APOE epsilon4 carriers (56% of the sample) showed poorer performance than non-carriers on the Mini Mental State Examination, a number of measures of verbal memory function from the California Verbal Learning Test, and visual recall. In 46% of the participants, psychometric criteria for amnestic Mild Cognitive Impairment (aMCI) were satisfied.

CONCLUSION

Findings may be partly explained by a significant number of participants being in a preclinical phase of Alzheimer's disease. The observed deficits in learning performance and the lack of significant age modulation of the genetic association suggest a more general genetic effect. The findings are consistent with known neurobiological function of APOE epsilon4, including both increased risk of neurodegenerative disease and reduced synaptic integrity in older age.

Role of apolipoprotein E in anxiety

Anxiety is most common among Alzheimer's disease (AD) patients with an age at onset under age 65. Apolipoprotein E4 (apoE4) is a risk factor for developing AD at an earlier age and might contribute to this effect. In mice, apoE plays a role in the regulation of anxiety, which might involve histamine receptor-mediated signaling and steroidogenesis in the adrenal gland. In addition, human apoE isoforms have differential effects on anxiety in adult mice lacking apoE and probable AD patients. Compared to wild-type mice, mice lacking apoE and apoE4 mice showed pathological alterations in the central nucleus of the amygdala, which is involved in regulation of anxiety. ApoE4, but not mice lacking apoE, or apoE3 mice showed impaired dexamethasone suppression of plasma corticosterone. Understanding how apoE modulates measures of anxiety might help the developments of therapeutic targets to reduce or even prevent measures of anxiety in health and in dementing illnesses.

Intelligence quotient-adjusted memory impairment is associated with abnormal single photon emission computed tomography perfusion

Cognitive reserve among highly intelligent older individuals makes detection of early Alzheimer's disease (AD) difficult. We tested the hypothesis that mild memory impairment determined by IQ-adjusted norms is associated with single photon emission computed tomography (SPECT) perfusion abnormality at baseline and predictive of future decline. Twenty-three subjects with a Clinical Dementia Rating (CDR) score of 0, were reclassified after scores were adjusted for IQ into two groups, 10 as having mild memory impairments for ability (IQ-MI) and 13 as memory-normal (IQ-MN). Subjects underwent cognitive and functional assessments at baseline and annual follow-up for 3 years. Perfusion SPECT was acquired at baseline. At follow-up, the IQ-MI subjects demonstrated decline in memory, visuospatial processing, and phonemic fluency, and 6 of 10 had progressed to a CDR of 0.5, while the IQ-MN subjects did not show decline. The IQ-MI group had significantly lower perfusion than the IQ-MN group in parietal/precuneus, temporal, and opercular frontal regions. In contrast, higher perfusion was observed in IQ-MI compared with IQ-MN in the left medial frontal and rostral anterior cingulate regions. IQ-adjusted memory impairment in individuals with high cognitive reserve is associated with baseline SPECT abnormality in a pattern consistent with prodromal AD and predicts subsequent cognitive and functional decline.

Use of functional magnetic resonance imaging in the early identification of Alzheimer's disease

A growing body of evidence suggests that a preclinical phase of Alzheimer's disease (AD) exists several years or more prior to the overt manifestation of clinical symptoms and is characterized by subtle neuropsychological and brain changes. Identification of individuals prior to the development of significant clinical symptoms is imperative in order to have the greatest treatment impact by maintaining cognitive abilities and preserving quality of life. Functional magnetic resonance imaging (fMRI) offers considerable promise as a non-invasive tool for detecting early functional brain changes in asymptomatic adults. In fact, evidence to date indicates that functional brain decline precedes structural decline in preclinical samples. Therefore, fMRI may offer the unique ability to capture the dynamic state of change in the degenerating brain. This review examines the clinical utility of blood oxygen level dependent (BOLD) fMRI in those at risk for AD as well as in early AD. We provide an overview of fMRI findings in at-risk groups by virtue of genetic susceptibility or mild cognitive decline followed by an appraisal of the methodological issues concerning the diagnostic usefulness of fMRI in early AD. We conclude with a discussion of future directions and propose that BOLD-fMRI in combination with cerebral blood flow or diffusion techniques will provide a more complete accounting of the neurovascular changes that occur in preclinical AD and thus improve our ability to reliably detect early brain changes prior to disease onset.

Cognitive Performance in Older Women Relative to ApoE-ε4 Genotype and Aerobic Fitness

INTRODUCTION

Apolipoprotein E (ApoE) genotype and aerobic fitness are each associated with cognitive performance in older adults. However, their potentially interactive effects on cognitive performance have not been examined.

PURPOSE

The primary purpose of this study was to determine whether ApoE genotype and aerobic fitness interact to uniquely impact memory performance and executive functioning. A secondary purpose was to examine the interactive effects on other measures of cognition to provide a more comprehensive assessment of cognitive abilities across a broad range of functions.

METHODS

Community-dwelling, cognitively normal older women (N = 90) provided blood samples to allow for assessment of ApoE genotype, completed cognitive tests, and performed a maximal aerobic fitness test. Primary outcome variables were the auditory verbal learning test (AVLT), the complex figures test (CFT), and the Wisconsin card-sorting task (WCST). Secondary outcome variables were the block design test and the paced auditory serial addition task (PASAT).

RESULTS

Regression analyses indicated that aerobic fitness was associated with significantly better performance on measures of the AVLT, the CFT, and the PASAT for the ApoE-epsilon4 homozygotes.

CONCLUSION

The preliminary findings from this study support the possibility that aerobic fitness is positively associated with the memory performance of those individuals at most genetic risk for Alzheimer disease.

Common Kibra alleles are associated with human memory performance

Human memory is a polygenic trait. We performed a genome-wide screen to identify memory-related gene variants. A genomic locus encoding the brain protein KIBRA was significantly associated with memory performance in three independent, cognitively normal cohorts from Switzerland and the United States. Gene expression studies showed that KIBRA was expressed in memory-related brain structures. Functional magnetic resonance imaging detected KIBRA allele-dependent differences in hippocampal activations during memory retrieval. Evidence from these experiments suggests a role for KIBRA in human memory.

Apolipoprotein E variants and cognition in healthy individuals: A critical opinion

The epsilon4 allele of apolipoprotein E (ApoE) is a well-established risk factor for late onset Alzheimer's disease (AD). This knowledge has generated interest in the role of ApoE variants in normal cognition. Varying degrees of cognitive dysfunction have been described in non-demented individuals with one or two epsilon4 alleles leading to suggestions that the gene plays a role in normal cognition or helps calibrate the aging process. In this paper, these hypotheses are critically evaluated. It is argued that ApoE variants play no role in cognitive development. Given the differential neurocognitive sequelae of normal aging and AD, we also suggest that accelerated aging is unlikely to account for the pattern of deficits observed in non-demented epsilon4 allele carriers. We conclude that the neuropsychological dysfunction reported in non-demented epsilon4 carriers is most likely to be the result of incipient AD.

A clinical perspective of mild cognitive impairment: what radiologists should know

Mild cognitive impairment (MCI), a major risk factor for dementia, has an amnestic subtype that has a high probability of progressing to Alzheimer's disease. The rate of progression may be predicted by the severity of memory impairment at baseline, the severity of hippocampal atrophy, and, possibly, the presence of an epsilon4 allele of the apolipoprotein E gene. MCI can be diagnosed using purely clinical or a combination of clinical and neuropsychologic criteria. Treatment trials show no disease-modifying effect. The radiologists' role is to determine whether or not the hallmarks of degenerative and vascular disease of the brain are present, aiding in the diagnosis of the cause of MCI.

Clinical trials in mild cognitive impairment: lessons for the future

Mild cognitive impairment (MCI) is an operational definition for a cognitive decline in individuals with a greater risk of developing dementia. The amnestic subtype of MCI is of particular interest because these individuals most likely progress to Alzheimer's disease (AD). Currently hypothesised therapeutic approaches in MCI are mainly based on AD treatment strategies. Long term secondary prevention randomised clinical trials have been completed in amnestic MCI populations, encompassing agents with various mechanisms of action: acetylcholinesterase inhibitors (donepezil, rivastigmine, galantamine), antioxidants (vitamin E), anti-inflammatories (rofecoxib), and nootropics (piracetam). The design of clinical trials in MCI is influenced by study objectives and definition of primary end points: time to clinical diagnosis of dementia, and AD in particular, or symptom progression. As none of the drugs previously shown to have clinical efficacy in AD trials or benefit in everyday practice have met the primary objectives of the respective trials, design of future clinical trials in MCI should be further developed particularly as regards the selection of more homogeneous samples at entry, optimal treatment duration, and multidimensional and reliable outcomes.

Reduced hippocampal activation during episodic encoding in middle-aged individuals at genetic risk of Alzheimer's disease: a cross-sectional study

BACKGROUND

The presence of the apolipoprotein E (APOE) epsilon4 allele is a major risk factor for the development of Alzheimer's disease (AD), and has been associated with metabolic brain changes several years before the onset of typical AD symptoms. Functional MRI (fMRI) is a brain imaging technique that has been used to demonstrate hippocampal activation during measurement of episodic encoding, but the effect of the epsilon4 allele on hippocampal activation has not been firmly established.

METHODS

The present study examined the effects of APOE genotype on brain activation patterns in the medial temporal lobe (MTL) during an episodic encoding task using a well-characterized novel item versus familiar item contrast in cognitively normal, middle-aged (mean = 54 years) individuals who had at least one parent with AD.

RESULTS

We found that epsilon3/4 heterozygotes displayed reduced activation in the hippocampus and MTL compared to epsilon3/3 homozygotes. There were no significant differences between the groups in age, education or neuropsychological functioning, suggesting that the altered brain activation seen in epsilon3/4 heterozygotes was not associated with impaired cognitive function. We also found that participants' ability to encode information on a neuropsychological measure of learning was associated with greater activation in the anterior MTL in the epsilon3/3 homozygotes, but not in the epsilon3/4 heterozygotes.

CONCLUSION

Together with previous studies reporting reduced glucose metabolism and AD-related neuropathology, this study provides convergent validity for the idea that the MTL exhibits functional decline associated with the APOE epsilon4 allele. Importantly, these changes were detected in the absence of meaningful neuropsychological differences between the groups. A focus of ongoing work in this laboratory is to determine if these findings are predictive of subsequent cognitive decline.

Longitudinal memory performance during normal aging: twin association models of APOE and other Alzheimer candidate genes

The APOE gene (apolipoprotein E) is a major risk factor for Alzheimer's Disease (AD) but has been inconsistently associated with memory in nondemented adults. Two other genes with mixed support as genetic risk factors for AD, A2M (alpha-2-macroglobulin) and LRP (low-density lipoprotein receptor-related protein), have not been studied in relation to memory among nondemented adults. The present study examined these three genes and latent growth parameters estimated from memory performance spanning 13 years in 478 twins from the Swedish Adoption/Twin Study of Aging (SATSA). APOE was associated with working and recall memory ability levels and working memory rate of change, with e4 homozygotes exhibiting the worst performance at all ages. Homozygotes for the rare A2M insertion/deletion variant exhibited accelerating decline on delayed figural recognition. There were no significant findings for LRP. Dominance, often untested in previous studies, was important in the current study's findings.

Apolipoprotein E and alpha brain rhythms in mild cognitive impairment: A multicentric Electroencephalogram study

OBJECTIVE

Relationships between the apolipoprotein E epsilon4 allele and electroencephalographic (EEG) rhythmicity have been demonstrated in Alzheimer's disease (AD) patients but not in the preclinical stage prodromic to it, namely, mild cognitive impairment (MCI). The present multicentric EEG study tested the hypothesis that presence of epsilon4 affects sources of resting EEG rhythms in both MCI and AD subjects.

METHODS

We enrolled 89 MCI subjects (34.8% with epsilon4) and 103 AD patients (50.4% with epsilon4). Resting eyes-closed EEG data were recorded for all subjects. EEG rhythms of interest were delta (2-4 Hz), theta (4-8 Hz), alpha 1 (8-10.5 Hz), alpha 2 (10.5-13Hz), beta 1 (13-20 Hz), and beta 2 (20-30 Hz). EEG cortical sources were estimated by low-resolution brain electromagnetic tomography.

RESULTS

Results showed that amplitude of alpha 1 and 2 sources in occipital, temporal, and limbic areas was lower in subjects carrying the epsilon4 allele than in those not carrying the epsilon4 allele (p < 0.01). This was true for both MCI and AD. For the first time to our knowledge, a relationship was shown between ApoE genotype and global neurophysiological phenotype (ie, cortical alpha rhythmicity) in a preclinical AD condition, MCI, in addition to clinically manifest AD.

INTERPRETATION

Such a demonstration motivates future genotype-EEG phenotype studies for the early prediction of AD conversion in individual MCI subjects.

Middle-aged children of persons with Alzheimer's disease: APOE genotypes and cognitive function in the Wisconsin Registry for Alzheimer's Prevention

Adult children of persons with Alzheimer's disease are at increased risk of developing Alzheimer's disease because of hereditary, environmental, and health risk factors shared with affected parents. The Wisconsin Registry for Alzheimer's Prevention (WRAP) has completed baseline assessments on 452 middle-aged persons (mean = 53 years) who have at least 1 parent with AD. Forty-five percent had 1 or more apolipoprotein (APOE) epsilon4 alleles. There were few significant differences between epsilon4 carriers and noncarriers in demographics, health, and lifestyle measures or in neuropsychological performance. The high percentage of WRAP participants who are carriers of APOE epsilon4 underscores their increased risk for developing Alzheimer's disease, but the absence of differences related to APOE status and high mean scores on cognitive tests suggests that the APOE epsilon4 gene has yet to have a clinical impact on cognitive functioning. The WRAP cohort may be a valuable group to follow prospectively to characterize the nature of cognitive change in relation to risk factors and to identify underlying preclinical neurobiological changes.

Apolipoprotein E epsilon4 and change in cognitive functioning in community-dwelling older adults

The relationship between apolipoprotein E (APOE) epsilon4 and change in cognition was examined in older men (n = 247; age = 75.0 +/- 3.5 years) and women (n = 79; age = 70.8 +/- 4.9 years) free of history of stroke. Participants were examined again 4.0 +/- 0.5 years later. Exclusion criteria were (1) initial scores on the Mini-Mental State Examination of 23 or less or (2) the presence of the APOE 2/4 genotype. Men with epsilon4 showed greater decline in some measures of executive function and verbal memory compared to those without epsilon4; women with epsilon4 showed greater decline in Trail Making test performance relative to women without the allele. A significant gender x APOE epsilon4 interaction was seen for change in performance on short delay cued recall. These results suggest that APOE epsilon4 is associated with cognitive decline differently in older adult men and women.

Subjective memory complaints in Chinese subjects with mild cognitive impairment and early Alzheimer's disease

BACKGROUND

Mild cognitive impairment (MCI) represents a transitional state between normal aging and dementia. However, there is inconsistent opinion as to the validity of subjective memory complaints as a criterion for diagnosis.

OBJECTIVE

This study aimed to examine the potential significance of applying a short memory questionnaire in the assessment of Chinese subjects with MCI and early dementia.

METHODS

Three hundred and six ambulatory Chinese subjects were recruited. Each participant completed a short memory questionnaire. They were also assessed with the Chinese versions of the mini-mental state examination (CMMSE), Alzheimer's disease assessment scale-cognitive subscale (ADAS-Cog), category verbal fluency test (CVFT) and span tests. Severity of cognitive impairment was evaluated using the Clinical Dementia Rating (CDR); subjects with CDR 0.5 were further classified into MCI not demented (MCIND) and MCI possible incipient dementia (MCIID) depending on the subscale scores of CDR.

RESULTS

An increasing frequency of memory complaints with increasing CDR was observed (Kruskal Wallis test, chi square = 21.29, df 3, p < 0.001). With a cutoff of 3 or more memory complaints, the memory questionnaire demonstrated a sensitivity of 65.3% and 70.4% in identifying subjects with incipient and early dementia respectively. Significant associations between memory complaints and most cognitive test performance were found (Spearman's correlations, p < 0.01). Logistic regression analysis revealed that educational level, the memory questionnaire, ADAS-Cog total and delayed recall scores were significant predictors of MCIID status.

CONCLUSIONS

The findings suggested that a short memory questionnaire is useful in the screening of MCI, particularly in subjects who already present with subtle functioning disturbances. Subjective memory complaints were significant correlated with objective performance of memory functions, reflecting the usefulness of memory complaints in the assessment of MCI.

ApoE epsilon4 allele and disease duration affect verbal learning in mild temporal lobe epilepsy

PURPOSE

To clarify the possible role of other factors including the ApoE epsilon4 allele for memory decline in temporal lobe epilepsy (TLE).

METHODS

We conducted a neuropsychological and molecular study in 138 consecutive patients (78 female patients; mean age, 50.2 years, SD +/- 17.9; range, 14 to 87 years) with mild nonlesional TLE, who rarely or never had seizures at long-term follow-up. The mean age at seizure onset was 33.0 years (SD, +/-21.7), and the mean duration of epilepsy was 17.1 years (SD, +/-15.7).

RESULTS

Thirty-four (25%) of 138 patients had test scores indicating verbal learning deficit (VLD). The presence of an ApoE epsilon4 allele was associated with an increased risk of VLD (OR, 4.18; 95% CI, 1.66-10.55). The effect of the ApoE genotype was independent of both the age at epilepsy onset and disease duration as well as of a low educational level, which were separately associated with VLD (p values = 0.045, 0.001, and 0.001, respectively). A significant linear trend (p = 0.005) was seen in the relation between disease duration and cognitive impairment, with the highest risk being in patients with an epilepsy duration > or =25.5 years (OR, 7.06; 95% CI, 1.67-29.85), especially if they carried the epsilon4 allele (OR, 32.29; 95% CI, 5.23-195.72).

CONCLUSIONS

These results provide evidence for an alteration in cognitive performance as a function of the presence of the ApoE epsilon4 allele and point to the critical role of disease duration itself for cognitive impairment in TLE.