Cognitive function and prediction of dementia in old age

Retinal mid-peripheral capillary free zones are enlarged in cognitively unimpaired older adults at high risk for Alzheimer's disease

BACKGROUND

Compared to standard neuro-diagnostic techniques, retinal biomarkers provide a probable low-cost and non-invasive alternative for early Alzheimer's disease (AD) risk screening. We have previously quantified the periarteriole and perivenule capillary free zones (mid-peripheral CFZs) in cognitively unimpaired (CU) young and older adults as novel metrics of retinal tissue oxygenation. There is a breakdown of the inner retinal blood barrier, pericyte loss, and capillary non-perfusion or dropout in AD leading to potential enlargement of the mid-peripheral CFZs. We hypothesized the mid-peripheral CFZs will be enlarged in CU older adults at high risk for AD compared to low-risk individuals.

METHODS

20 × 20° optical coherence tomography angiography images consisting of 512 b-scans, 512 A-scans per b-scan, 12-µm spacing between b-scans, and 5 frames averaged per each b-scan location of the central fovea and of paired major arterioles and venules with their surrounding capillaries inferior to the fovea of 57 eyes of 37 CU low-risk (mean age: 66 years) and 50 eyes of 38 CU high-risk older adults (mean age: 64 years; p = 0.24) were involved in this study. High-risk participants were defined as having at least one APOE e4 allele and a positive first-degree family history of AD while low-risk participants had neither of the two criteria. All participants had Montreal Cognitive Assessment scores ≥ 26. The mid-peripheral CFZs were computed in MATLAB and compared between the two groups.

RESULTS

The periarteriole CFZ of the high-risk group (75.8 ± 9.19 µm) was significantly larger than that of the low-risk group (71.3 ± 7.07 µm), p = 0.005, Cohen's d = 0.55. The perivenule CFZ of the high-risk group (60.4 ± 8.55 µm) was also significantly larger than that of the low-risk group (57.3 ± 6.40 µm), p = 0.034, Cohen's d = 0.42. There were no significant differences in foveal avascular zone (FAZ) size, FAZ effective diameter, and vessel density between the two groups, all p > 0.05.

CONCLUSIONS

Our results show larger mid-peripheral CFZs in CU older adults at high risk for AD, with the potential for the periarteriole CFZ to serve as a novel retinal vascular biomarker for early AD risk detection.

The effect of insomnia on development of Alzheimer's disease

Alzheimer's disease (AD) is the most common type of dementia and a neurodegenerative disorder characterized by memory deficits especially forgetting recent information, recall ability impairment, and loss of time tracking, problem-solving, language, and recognition difficulties. AD is also a globally important health issue but despite all scientific efforts, the treatment of AD is still a challenge. Sleep has important roles in learning and memory consolidation. Studies have shown that sleep deprivation (SD) and insomnia are associated with the pathogenesis of Alzheimer's disease and may have an impact on the symptoms and development. Thus, sleep disorders have decisive effects on AD; this association deserves more attention in research, diagnostics, and treatment, and knowing this relation also can help to prevent AD through screening and proper management of sleep disorders. This study aimed to show the potential role of SD and insomnia in the pathogenesis and progression of AD.

Genome-wide association study of cognitive function in diverse Hispanics/Latinos: results from the Hispanic Community Health Study/Study of Latinos

Cognitive function such as reasoning, attention, memory, and language is strongly correlated with brain aging. Compared to non-Hispanic whites, Hispanics/Latinos have a higher risk of cognitive impairment and dementia. The genetic determinants of cognitive function have not been widely explored in this diverse and admixed population. We conducted a genome-wide association analysis of cognitive function in up to 7600 middle aged and older Hispanics/Latinos (mean = 55 years) from the Hispanic Community Health Study / Study of Latinos (HCHS/SOL). Four cognitive measures were examined: the Brief Spanish English Verbal Learning Test (B-SEVLT), the Word Fluency Test (WFT), the Digit Symbol Substitution Test (DSST), the Six-Item Screener (SIS). Four novel loci were identified: one for B-SEVLT at 4p14, two for WFT at 3p14.1 and 6p21.32, and one for DSST at 10p13. These loci implicate genes highly expressed in brain and previously connected to neurological diseases (UBE2K, FRMD4B, the HLA gene complex). By applying tissue-specific gene expression prediction models to our genotype data, additional genes highly expressed in brain showed suggestive associations with cognitive measures possibly indicating novel biological mechanisms, including IFT122 in the hippocampus for SIS, SNX31 in the basal ganglia for B-SEVLT, RPS6KB2 in the frontal cortex for WFT, and CSPG5 in the hypothalamus for DSST. These findings provide new information about the genetic determinants of cognitive function in this unique population. In addition, we derived a measure of general cognitive function based on these cognitive tests and generated genome-wide association summary results, providing a resource to the research community for comparison, replication, and meta-analysis in future genetic studies in Hispanics/Latinos.

Proteinuria and Reduced Estimated Glomerular Filtration Rate are Independently Associated With Lower Cognitive Abilities in Apparently Healthy Community-Dwelling Elderly Men in Japan: A Cross-sectional Study

BACKGROUND

The association of proteinuria and reduced estimated glomerular filtration rate (eGFR) with cognition needs more clarification. We cross-sectionally examined whether proteinuria and reduced eGFR, even in moderate stages, were independently associated with lower cognition in a community-based sample of elderly men.

METHODS

Our cohort initially comprised 1,094 men aged 40-79 years from a random sample from Shiga, Japan in 2006-2008. Of 853 men who returned for the follow-up examination (2009-2014), we analyzed 561 who were ≥65 years, free of stroke, and completed the Cognitive Abilities Screening Instrument (CASI) at follow-up (higher CASI scores [range 0 to 100] indicate better cognition). Proteinuria was assessed via dipstick. eGFR was calculated according to the Chronic Kidney Disease Epidemiology Collaboration Equation. Participants were divided into three groups either by eGFR (≥60, 59-40, and <40 mL/min/1.73 m2) or by proteinuria (no, trace, and positive), considered normal, moderate, and advanced, respectively. Using linear regression, we computed mean CASI score, with simultaneous adjustment for proteinuria and eGFR in addition to other potential confounders.

RESULTS

Significant trends of lower cognition were observed across the groups of worse proteinuria and lower eGFR independently: multivariable-adjusted mean CASI scores were 90.1, 89.3, and 88.4 for proteinuria (Ptrend = 0.029), and 90.0, 88.5, and 88.5 for eGFR (Ptrend = 0.015) in mutual-adjustment model.

CONCLUSIONS

Proteinuria and reduced eGFR, even in their moderate stages, were independently associated with lower cognition in a community-based sample of elderly men. The results suggest the importance of proteinuria and low eGFR for early detection and prevention of cognitive decline.

Distinguishing cognitive impairment by using singularity spectrum and lacunarity analysis of the retinal vascular network

The development of effective therapies for cognitive impairment (CI), especially due to Alzheimer's disease, demands diagnosing the condition during the prodromal phase. The diagnosis of CI involves expensive and invasive methods, such as positron emission tomography and cerebrospinal fluid assessment via spinal tap. Hence, a comparatively lower cost and noninvasive method of diagnosis is imperative. The human retina is an extension of the brain characterized by similarities in vascular and neural structures. The complications of CI are not only limited to the brain but also affect the retina for which the loss of retinal ganglion cells has been associated with neurodegeneration in the brain. The loss of retinal ganglion cells in individuals with CI may be related to reduced vascular demand and a potential remodeling of the retinal vascular branching complexity. Retinal imaging biomarkers may provide a low cost and noninvasive alternative for the diagnosis of CI. In this study, the retinal vascular branching complexity of patients with CI was characterized using the singularity spectrum multifractal dimension and lacunarity parameter. A reduced vascular branching complexity was observed in subjects with CI when compared to age- and sex-matched cognitively healthy controls. Significant associations were also found between retinal vascular and functional parameters.

Identification of Retinal Biomarkers in Alzheimer's Disease Using Optical Coherence Tomography: Recent Insights, Challenges, and Opportunities

This review will highlight recent insights into measuring retinal structure in Alzheimer’s disease (AD). A growing body of evidence indicates that disturbances in retinal blood flow and structure are related to cognitive function, which can severely impair vision. Optical coherence tomography (OCT) is an optical imaging technology that may allow researchers and physicians to gain deeper insights into retinal morphology and clarify the impact of AD on retinal health and function. Direct and noninvasive measurement of retinal morphology using OCT has provided useful diagnostic and therapeutic indications in several central nervous system (CNS) diseases, including AD, multiple sclerosis, and Parkinson disease. Despite several limitations, morphology assessment in the retinal layers is a significant advancement in the understanding of ocular diseases. Nevertheless, additional studies are required to validate the use of OCT in AD and its complications in the eye.

Lifespan Changes of the Human Brain In Alzheimer's Disease

Brain imaging studies have shown that slow and progressive cerebral atrophy characterized the development of Alzheimer's Disease (AD). Despite a large number of studies dedicated to AD, key questions about the lifespan evolution of AD biomarkers remain open. When does the AD model diverge from the normal aging model? What is the lifespan trajectory of imaging biomarkers for AD? How do the trajectories of biomarkers in AD differ from normal aging? To answer these questions, we proposed an innovative way by inferring brain structure model across the entire lifespan using a massive number of MRI (N = 4329). We compared the normal model based on 2944 control subjects with the pathological model based on 3262 patients (AD + Mild cognitive Impaired subjects) older than 55 years and controls younger than 55 years. Our study provides evidences of early divergence of the AD models from the normal aging trajectory before 40 years for the hippocampus, followed by the lateral ventricles and the amygdala around 40 years. Moreover, our lifespan model reveals the evolution of these biomarkers and suggests close abnormality evolution for the hippocampus and the amygdala, whereas trajectory of ventricular enlargement appears to follow an inverted U-shape. Finally, our models indicate that medial temporal lobe atrophy and ventricular enlargement are two mid-life physiopathological events characterizing AD brain.

Investigating Multimodal Diagnostic Eye Biomarkers of Cognitive Impairment by Measuring Vascular and Neurogenic Changes in the Retina

Previous studies have demonstrated that cognitive impairment (CI) is not limited to the brain but also affects the retina. In this pilot study, we investigated the correlation between the retinal vascular complexity and neurodegenerative changes in patients with CI using a low-cost multimodal approach. Quantification of the retinal structure and function were conducted for every subject (n = 69) using advanced retinal imaging, full-field electroretinogram (ERG) and visual performance exams. The retinal vascular parameters were calculated using the Singapore Institute Vessel Assessment software. The Montreal Cognitive Assessment was used to measure CI. Pearson product moment correlation was performed between variables. Of the 69 participants, 32 had CI (46%). We found significantly altered microvascular network in individuals with CI (larger venular-asymmetry factor: 0.7 ± 0.2) compared with controls (0.6 ± 0.2). The vascular fractal dimension was lower in individuals with CI (capacity, information and correlation dimensions: D₀, D_1, and D₂ (mean ± SD): 1.57 ± 0.06; 1.56 ± 0.06; 1.55 ± 0.06; age 81 ± 6years) vs. controls (1.61 ± 0.03; 1.59 ± 0.03; 1.58 ± 0.03; age: 80 ± 7 years). Also, drusen-like regions in the peripheral retina along with pigment dispersion were noted in subjects with mild CI. Functional loss in color vision as well as smaller ERG amplitudes and larger peak times were observed in the subjects with CI. Pearson product moment correlation showed significant associations between the vascular parameters (artery-vein ratio, total length-diameter ratio, D₀, D₁, D₂ and the implicit time (IT) of the flicker response but these associations were not significant in the partial correlations. This study illustrates that there are multimodal retinal markers that may be sensitive to CI decline, and adds to the evidence that there is a statistical trend pointing to the correlation between retinal neuronal dysfunction and microvasculature changes suggesting that retinal geometric vascular and functional parameters might be associated with physiological changes in the retina due to CI. We suspect our analysis of combined structural-functional parameters, instead of individual biomarkers, may provide a useful clinical marker of CI that could also provide increased sensitivity and specificity for the differential diagnosis of CI. However, because of our study sample was small, the full extent of clinical applicability of our approach is provocative and still to be determined.

Identification of Heterogeneous Cognitive Subgroups in Community-Dwelling Older Adults: A Latent Class Analysis of the Einstein Aging Study

OBJECTIVES

The aim of this study was to identify natural subgroups of older adults based on cognitive performance, and to establish each subgroup's characteristics based on demographic factors, physical function, psychosocial well-being, and comorbidity.

METHODS

We applied latent class (LC) modeling to identify subgroups in baseline assessments of 1345 Einstein Aging Study (EAS) participants free of dementia. The EAS is a community-dwelling cohort study of 70+ year-old adults living in the Bronx, NY. We used 10 neurocognitive tests and 3 covariates (age, sex, education) to identify latent subgroups. We used goodness-of-fit statistics to identify the optimal class solution and assess model adequacy. We also validated our model using two-fold split-half cross-validation.

RESULTS

The sample had a mean age of 78.0 (SD=5.4) and a mean of 13.6 years of education (SD=3.5). A 9-class solution based on cognitive performance at baseline was the best-fitting model. We characterized the 9 identified classes as (i) disadvantaged, (ii) poor language, (iii) poor episodic memory and fluency, (iv) poor processing speed and executive function, (v) low average, (vi) high average, (vii) average, (viii) poor executive and poor working memory, (ix) elite. The cross validation indicated stable class assignment with the exception of the average and high average classes.

CONCLUSIONS

LC modeling in a community sample of older adults revealed 9 cognitive subgroups. Assignment of subgroups was reliable and associated with external validators. Future work will test the predictive validity of these groups for outcomes such as Alzheimer's disease, vascular dementia and death, as well as markers of biological pathways that contribute to cognitive decline. (JINS, 2018, 24, 511-523).

Do We Try Mending Humpty Dumpty or Prevent His Fall? An Alzheimer's Disease Dilemma

In the popular nursery rhyme, Humpty Dumpty's great fall and the inability to put him together again has been used to demonstrate the second law of thermodynamics. An oversimplification of this law states that all things in the universe tend to move from order to disorder, an occurrence that can be applied allegorically to the development and clinical outcome of Alzheimer's disease (AD). An important argument relevant to the future use of resources and primary focus of AD research arises from the question, do we make it a priority to mend the shattered brain of AD patients or attempt to prevent the brain from shattering? If the former approach continues to be the priority it has become, how exactly do we mend the irreparable neuronal loss and associated cognitive failure in advanced cases of AD? Or, must we change direction and make prevention the primary goal of AD research? The latter approach would identify asymptomatic or mildly symptomatic patients with high risk of developing dementia by means of establishing multidisciplinary heart-brain clinics that would provide either close observation or a tailored therapeutic intervention. This is an important challenge that needs to be achieved if the AD incidence, societal costs and suffering, is to be significantly reduced.

Catechol-O-methyltransferase Val158Met polymorphism on the relationship between white matter hyperintensity and cognition in healthy people

Background

White matter lesions can be easily observed on T2-weighted MR images, and are termed white matter hyperintensities (WMH). Their presence may be correlated with cognitive impairment; however, the relationship between regional WMH volume and catechol-O-methyltransferase (COMT) Val158Met polymorphism in healthy populations remains unclear.

Methods

We recruited 315 ethnic Chinese adults with a mean age of 54.9±21.8 years (range: 21–89 y) to examine the genetic effect of COMT on regional WMH and the manner in which they interact to affect cognitive function in a healthy adult population. Cognitive tests, structural MRI scans, and genotyping of COMT were conducted for each participant.

Results

Negative correlations between the Digit Span Forward (DSF) score and frontal WMH volumes (r = −.123, P = .032, uncorrected) were noted. For the genetic effect of COMT, no significant difference in cognitive performance was observed among 3 genotypic groups. However, differences in WMH volumes over the subcortical region (P = .016, uncorrected), whole brain (P = .047, uncorrected), and a trend over the frontal region (P = .050, uncorrected) were observed among 3 COMT genotypic groups. Met homozygotes and Met/Val heterozygotes exhibited larger WMH volumes in these brain regions than the Val homozygotes. Furthermore, a correlation between the DSF and regional WMH volume was observed only in Met homozygotes. The effect size (cohen’s f) revealed a small effect.

Conclusions

The results indicate that COMT might modulate WMH volumes and the effects of WMH on cognition.

Foreign language training as cognitive therapy for age-related cognitive decline: a hypothesis for future research

Over the next fifty years, the number of older adults is set to reach record levels. Protecting older adults from the age-related effects of cognitive decline is one of the greatest challenges of the next few decades as it places increasing pressure on families, health systems, and economies on a global scale. The disease-state of age-related cognitive decline-Alzheimer's disease and other dementias-hijacks our consciousness and intellectual autonomy. However, there is evidence that cognitively stimulating activities protect against the adverse effects of cognitive decline. Similarly, bilingualism is also considered to be a safeguard. We propose that foreign language learning programs aimed at older populations are an optimal solution for building cognitive reserve because language learning engages an extensive brain network that is known to overlap with the regions negatively affected by the aging process. It is recommended that future research should test this potentially fruitful hypothesis.

Late effects of adjuvant chemotherapy for adult onset non-CNS cancer; cognitive impairment, brain structure and risk of dementia

Few studies have investigated the late (i.e. ≥ 5 years post-treatment) effects of chemotherapy for non-central nervous system (non-CNS) cancer on the brain. Here we discuss the studies that have investigated the late effects of adjuvant chemotherapy for non-CNS cancer on cognitive function (n=6); brain structure and function (n=5); and incidence of dementia (n=4). The neuropsychological studies showed long-term adverse cognitive problems in chemotherapy-exposed breast cancer survivors. This is in line with results from neuroimaging studies that report long-term brain structural alterations after chemotherapy. The studies exploring the association between chemotherapy and the incidence of dementia were contradictive and showed no clear relationship between the two phenomena. Although several methodological issues limit the validity and interpretation of some of the results of these studies, they suggest that chemotherapy is associated with subtle, yet long-lasting cognitive deficits, possibly related to brain structural and functional differences, but as yet not with an increased risk of dementia.

Alzheimer's disease genes and cognition in the nondemented general population

BACKGROUND

Genome-wide association studies have established 11 genes for late-onset Alzheimer's disease (AD). We investigated whether these genes jointly affect cognition in a nondemented population and improve prediction of AD.

METHODS

In 5171 nondemented people (age 45-99 years) from the population-based Rotterdam Study, we genotyped APOE-ε4 and single nucleotide polymorphisms from the genes CLU, PICALM, BIN1, CR1, ABCA7, MS4A6A, MS4A4E, CD2AP, EPHA1, and CD33. We constructed a genetic risk score by adding the risk alleles per individual weighted by the reported effect sizes. All people underwent cognitive testing. With linear regression we investigated the relationship between the genetic risk score and cognition, with and without APOE. In a subcohort, with more than 10 years of follow-up, we assessed whether the risk score predicted AD.

RESULTS

The genetic risk score was primarily associated with memory (standardized difference [95% confidence interval] per SD increase in genetic risk score: -.05[-.07; -.02], p = 1.5 * 10(-4)). This association attenuated when APOE was excluded from the genetic risk score (-.03[-.05; .00], p = .047) and would not survive a multiple-testing correction. Similarly, we found that although the genetic risk score without APOE was associated with the development of AD (p = .010), it only marginally improved prediction of AD beyond age, sex, APOE (area under the curve: .8159 vs. .8148).

CONCLUSIONS

In nondemented people, there is only a marginal joint effect of AD genes on memory independent from APOE. Moreover, although associated with AD, these genes jointly hardly improve prediction of AD.

Susceptibility to distraction during reading in young, young-old, and old-old adults

BACKGROUND/STUDY CONTEXT: Susceptibility to distraction during reading may increase with age, resulting in comprehension errors. Neurological integrity and cognitive reserve are possible covariates of age-related distraction susceptibility. The current study investigated distraction susceptibility in three age groups (young, young-old, and old-old), and examined the covariation patterns of variable sets associated with neurological integrity and cognitive reserve.

METHODS

Participants responded to comprehension questions after reading stories that included semantically related or semantically unrelated distractors. Neurological integrity measures consisted of Mini-Mental State Examination, Selective Reminding, and Category Fluency. Cognitive reserve measures consisted of education and vocabulary.

RESULTS

Old-old adults were more likely than young and young-old adults to select distractors when responding to comprehension questions (24.02%, 11.95%, 3.68%, respectively). Age-related distraction variance significantly overlapped neurological variance, and became more transparent after cognitive reserve variance was controlled.

CONCLUSION

This study augments previous age-related distraction research by highlighting (a) the increase in distraction susceptibility in adults over 79, particularly when distractors are semantically related; (b) the influence of age-related neurological integrity on distraction; and (c) the possibility that education and verbal experience may decrease distraction susceptibility, consistent with cognitive reserve frameworks.

Mild cognitive impairment: an epidemiological perspective

Mild cognitive impairment (MCI) refers to cognitive impairment that is assumed to be due to pathological central nervous system processes, but which interacts with normal aging-related changes. Epidemiological studies conducted in the general population have been able to examine more heterogeneous forms of this disorder than clinical studies, and have also been able to provide early estimations of population incidence and prevalence. Large differences in case identification procedures and sampling methods have led to considerable divergence in the rates of prevalence reported, which ranged from 1% to 29%. Suggested improvements in the definition of MCI have led to an upward adjustment of prevalence rates in most studies, giving between 5% and 29%. Incidence is estimated as 8 to 58 new cases per thousand persons per year, and the probability of conversion from MCI to dementia is estimated at around 15%. The principal risk factors that have been identified so far for MCI using regression models applied to general population data are age, education, race, medicated hypertension, infarcts, white matter lesions, depression, and apolipoprotein E4 (AP0E-4J allele. An etiological model derived from these studies indicates possible intervention points for future therapeutic strategies at the level of both clinical intervention and environmental exposure. There is, however, a clear need for epidemiological studies that take into account a broader range of risk factors than those studied to date, which have focused principally on known risk factors for dementia.

The PREVENT study: a prospective cohort study to identify mid-life biomarkers of late-onset Alzheimer's disease

INTRODUCTION

Epidemiological studies indicate that significant decreases in the incidence of Alzheimer's disease (AD) may be obtained by targeting multiple middle-age risk factors. However, as dementia is unlikely to be diagnosed for decades, short-term outcome measures are required. AD biomarker changes precede clinical symptoms by many years, but their sensitivity to mid-life change remains unknown.

METHODS AND ANALYSIS

PREVENT is a prospective cohort study examining biomarker status at mid-life in at least 150 individuals genetically at high, medium or low risk of late-onset AD. Participants are children of individuals with or without a diagnosed AD allocated to high, medium and low-risk groups according to parental clinical status and ApoE genotype. The biomarkers examined over 2 years are plasma and CSF Aβ42 amyloid, Tau and pTau, proinflammatory cytokines, acute-phase proteins, medial temporal-lobe atrophy, white matter lesion volume, cognitive performance related to transentorhinal and hippocampal functioning and hypothalamic-pituitary-adrenal and sympathetic axes regulation.

ETHICS AND DISSEMINATION

Detected pathologies are communicated to the participant's general practitioner with their permission. Risk status by genotype would not be revealed. The results of the study would be published in peer-reviewed journals and validated biomarkers used to construct a randomised controlled intervention study.

Secular changes in cognitive predictors of dementia and mortality in 70-year-olds

BACKGROUND

Successive elderly birth cohorts improved in cognitive performance during the 20th century. It is not clear whether this influences cognitive predictors of dementia and mortality.

OBJECTIVE

In 2 longitudinal population studies, representing 2 cohorts of 70-year-olds examined 30 years apart, we investigated the relation between baseline cognitive function and 5-year occurrence of dementia and mortality.

METHODS

Two representative cohorts of 70-year-olds initially free from dementia born in 1901-1902 (cohort 1901-1902: n = 381) and 1930 (cohort 1930: n = 551) from Gothenburg, Sweden, were examined in 1971-1972 and 2000-2001 and after 5 years for the outcome of dementia and death. Recent memory was evaluated during psychiatric examinations, and nonmemory domains using psychometric tests.

RESULTS

At age 70, cohort 1930 performed better on psychometric tests, and had fewer recent memory problems compared to cohort 1901-1902. During 5-year follow-up, 5.0% in cohort 1901-1902 and 4.4% in cohort 1930 (p = 0.742) developed dementia, and 15.7% in cohort 1901-1902 and 4.4% in cohort 1930 died (p < 0.001). Recent memory was associated with incident dementia in both cohorts. Low scores in nonmemory tests were associated with incident dementia in cohort 1901-1902, but not in cohort 1930. Recent memory problems and lower scores in nonmemory tests were associated with 5-year mortality in cohort 1901-1902, but not in cohort 1930.

CONCLUSIONS

Secular changes in cognitive performance may influence cognitive predictors of dementia and mortality, despite similar incidence of dementia. The findings should be taken cautiously due to differences between cohorts in refusal rates, quality of education, and dementia recognition in medical records.

Retrospective identification and characterization of mild cognitive impairment from a prospective population cohort

OBJECTIVES

Mild cognitive impairment (MCI) case-finding criteria have low specificity in general population studies. This study retrospectively identifies cases of MCI and determines baseline criteria giving the highest discriminability. The ability of these criteria to increase current case detection specificity is estimated.

DESIGN

A population-based cohort was recruited from electoral rolls from three French cities. Clinical and environmental characteristics were evaluated at baseline and at 2- and 4-year follow-up. The clinical characteristics of incident cases of dementia were examined retrospectively.

PARTICIPANTS

Eight thousand nine hundred nineteen persons aged 65 years and older without dementia (60.8% women) were included in this study. The mean age (SD) of the participants was 74.2 (5.6) years for men and 74.4 (5.6) years for women.

RESULTS

Three hundred twenty persons (3.6%) were retrospectively classified as MCI at baseline. This MCI group had poorer performance on all cognitive tests compared with the rest of the cohort, and a subsample undergoing MRI were found to have more white matter hyperintensities. The group were also characterized by the presence of an ApoE ε4 genotype (odds ratio [OR]: 2.17, confidence interval [CI]: 1.44-3.29 for men; OR: 2.27, CI: 1.59-3.24 for women) and instrumental activities of daily living loss (OR: 1.72, CI: 1.01-3.0 for men; OR: 1.49; CI: 0.97-2.3 for women). Women with MCI also had high depressive symptomatology (OR: 1.96; CI: 1.34-2.87), anticholinergic drug use (OR: 1.59; CI: 1.05-2.28), and low body mass index (OR: 1.54, CI: 1.05-2.28) and for men a history of stroke (OR: 2.17, CI: 1.16-4.05) and glycemia (OR: 1.72, CI: 1.13-2.71). Addition of these characteristics to conventional MCI definitions increases their specificity.

CONCLUSIONS

This general population study using a retrospective method for classifying persons with MCI identified gender-specific noncognitive clinical variables that may increase specificity.

Mary S. Easton Center of Alzheimer's Disease Research at UCLA: advancing the therapeutic imperative

The Mary S. Easton Center for Alzheimer's Disease Research (UCLA-Easton Alzheimer's Center) is committed to the "therapeutic imperative" and is devoted to finding new treatments for Alzheimer's disease (AD) and to developing technologies (biomarkers) to advance that goal. The UCLA-Easton Alzheimer's Center has a continuum of research and research-related activities including basic/foundational studies of peptide interactions; translational studies in transgenic animals and other animal models of AD; clinical research to define the phenotype of AD, characterize familial AD, develop biomarkers, and advance clinical trials; health services and outcomes research; and active education, dissemination, and recruitment activities. The UCLAEaston Alzheimer's Center is supported by the National Institutes on Aging, the State of California, and generous donors who share our commitment to developing new therapies for AD. The naming donor (Jim Easton) provided substantial funds to endow the center and to support projects in AD drug discovery and biomarker development. The Sidell-Kagan Foundation supports the Katherine and Benjamin Kagan Alzheimer's Treatment Development Program, and the Deane F. Johnson Alzheimer's Research Foundation supports the Deane F. Johnson Center for Neurotherapeutics at UCLA. The John Douglas French Alzheimer's Research Foundation provides grants to junior investigators in critical periods of their academic development. The UCLA-Easton Alzheimer's Center partners with community organizations including the Alzheimer's Association California Southland Chapter and the Leeza Gibbons memory Foundation. Collaboration with pharmaceutical companies, biotechnology companies, and device companies is critical to developing new therapeutics for AD and these collaborations are embraced in the mission of the UCLA-Easton Alzheimer's Center. The Center supports excellent senior 3 investigators and serves as an incubator for new scientists, agents, models, technologies and concepts that will significantly influence the future of AD treatment and AD research.

Being overweight in midlife is associated with lower cognitive ability and steeper cognitive decline in late life

BACKGROUND

Although an increasing body of evidence links being overweight in midlife with an increased risk for dementia in late life, no studies have examined the association between being overweight in midlife and cognitive ability in late life. Our aim was to examine the association between being overweight in midlife as measured by body mass index (BMI) and cognitive ability assessed over time.

METHODS

Participants in the Swedish Adoption/Twin Study Aging were derived from a population-based sample. The participants completed baseline surveys in 1963 or 1973 (mean age 41.6 years, range 25-63 years). The surveys included questions about height, weight, diseases, and lifestyle factors. Beginning in 1986, the same individuals were assessed on neuropsychological tests every 3 years (except in 1995) until 2002. During the study period, 781 individuals who were 50 years and older (60% women) had at least one complete neuropsychological assessment. A composite score of general cognitive ability was derived from the cognitive test battery for each measurement occasion.

RESULTS

Latent growth curve models adjusted for twinness showed that persons with higher midlife BMI scores had significantly lower general cognitive ability and significantly steeper longitudinal decline than their thinner counterparts. The association did not change substantially when persons who developed dementia during the study period were excluded from the analysis.

CONCLUSIONS

Higher midlife BMI scores precede lower general cognitive ability and steeper cognitive decline in both men and women. The association does not seem to be mediated by an increased risk for dementia.

Age-related changes in memory and fluid reasoning in a sample of healthy old people

Participants in the Healthy Old People in Edinburgh (HOPE) study (N = 398) were assessed on Raven's Progressive Matrices and Logical Memory on up to three occasions. Covariates included education, social class, disease and medication status, blood pressure and study outcome. Raven's score declined linearly with age, whereas decline in Logical Memory was accelerating. There was significant variation in individuals' rates of decline for Ravens but not Logical Memory. Slope-intercept covariances were not significant. Those who later developed dementia already exhibited lower scores, more so for Logical Memory than Raven's. Death and study attrition were related to performance, again greater for Logical Memory.

CONCLUSIONS

The HOPE approach of progressive screening is a feasible and practical method for studying healthy cognitive ageing. As predicted for an initially healthy sample, rates of decline were relatively homogeneous. The hypothesis of differential decline was not supported, nor was a strict interpretation of the hypothesis that cognitive ageing is entirely pathology driven.

Text comprehension products and processes in young, young-old, and old-old adults

Aging may be associated with an increase in generalized text processing, particularly in adults older than 75 years. The current study examined text comprehension in young, young-old, and old-old adults. Experiment 1 included a comprehension measure (product) and Experiment 2 examined inferences generated during reading (process). Comprehension scores were lowest in old-old adults. Generalized and elaborative inference scores were highest in old-old adults. Participants over 65 years with the lowest scores on cognitive integrity variables also had significantly lower comprehension scores, but there was no effect of cognitive integrity on inference scores. This dissociation suggests that inferential processes may be maintained even when cognitive integrity and comprehension declines are present. Relevance to cognitive aging theories addressing text processing and self-regulatory processes is addressed.

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 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.

Soap operas and talk shows on television are associated with poorer cognition in older women

BACKGROUND

No information exists regarding whether a favorite television category choice affects attention, memory, or cognition among older women.

METHODS

Cross-sectional data from a population-based community sample of 289 older cognitively and physically intact women who were surveyed about television use. The cognitive battery included measures of psychomotor speed, executive attention, immediate and delayed verbal memory, and global cognition.

RESULTS

Talk shows (P < 0.05) or soap operas (P < 0.05) as a favorite television category were consistently associated with poorer scores on all cognitive outcomes in both unadjusted and adjusted analyses. Clinically significant cognitive impairment across domains were associated with watching talk shows (OR = 7.3; 95% CI = 1.9, 28.4) and soap operas (OR = 13.5; 95% CI = 3.7, 49.5).

CONCLUSIONS

Clinical interviews can incorporate questions about television viewing habits. Endorsements of talk shows or soap operas as frequent and favored television programming may identify those at risk for cognitive impairment and targets for further cognitive screening.

Performance on neurocognitive tests by co-twins to dementia cases compared to normal control twins

Nondemented co-twins of twins who were diagnosed as demented were compared to randomly selected members of normal control twin pairs in which both members of the pair were nondemented. Nondemented co-twins included 23 monozygotic and 62 dizygotic twins; there were 27 normal control twins. Both monozygotic and dizygotic nondemented co-twins of dementia cases scored significantly lower than normal control twins on 5 of 10 cognitive tests. Moreover, monozygotic co-twins of dementia cases had a generally lower score profile than dizygotic co-twins of dementia cases did. These findings show that being at greater genetic risk for dementia is reflected in cognitive performance even in the absence of a diagnosis of dementia.

Very early detection of Alzheimer neuropathology and the role of brain reserve in modifying its clinical expression

Numerous studies show that the pathology of Alzheimer's disease is present decades before a clinical diagnosis of dementia can be made. Given the likelihood that agents will become available that reliably delay onset and/or slow progression of Alzheimer's disease, it will be important to detect preclinical Alzheimer's disease as early as possible for maximal treatment effect. Detection of individuals by sensitive cognitive measures provides one way to identify people who are at high risk of developing clinical Alzheimer's disease. However, it is likely that those with considerable brain or cognitive reserve will be able to mask cognitive deficits until very close to the onset of the dementia, rendering such cognitive measures insensitive. Optimum biomarkers for Alzheimer's disease therefore need to target the severity of underlying brain pathology independently of brain reserve. Findings are presented showing the importance of higher education and larger brain size in masking the underlying disease pathology.

[Diagnosis of Alzheimer's disease in Brazil: cognitive and functional evaluation. Recommendations of the Scientific Department of Cognitive Neurology and Aging of the Brazilian Academy of Neurology]

The educational and cultural heterogeneity of the Brazilian population leads to peculiar characteristics regarding the diagnosis of Alzheimer's disease (AD). This consensus had the objective of recommending evidence-based guidelines for the clinical diagnosis of AD in Brazil. Studies on the diagnosis of AD published in Brazil were systematically evaluated in a thorough research of PUBMED and LILACS databases. For global cognitive evaluation, the Mini-Mental State Examination was recommended; for memory evaluation: delayed recall subtest of CERAD or of objects presented as drawings; attention: trail-making or digit-span; language: Boston naming, naming test from ADAS-Cog or NEUROPSI; executive functions: verbal fluency or clock-drawing; conceptualization and abstraction: similarities from CAMDEX or NEUROPSI; construction: drawings from CERAD. For functional evaluation, IQCODE, or Pfeffer Questionnaire or Bayer Scale for Activities of Daily Living was recommended. The panel concluded that the combined use of cognitive and functional evaluation based on interview with informant is recommended.

Multiple cognitive deficits during the transition to Alzheimer's disease

The literature on cognitive markers in preclinical AD is reviewed. The findings demonstrate that impairment in multiple cognitive domains is typically observed several years before clinical diagnosis. Measures of executive functioning, episodic memory and perceptual speed appear to be most effective at identifying at-risk individuals. The fact that these cognitive domains are most implicated in normal cognitive aging suggests that the cognitive deficit observed preclinically is not qualitatively different from that observed in normal aging. The degree of cognitive impairment prior to the diagnosis of Alzheimer's disease (AD) appears to generalize relatively well across major study characteristics, including sample ascertainment procedures, age and cognitive status of participants, as well as time to diagnosis of dementia. In episodic memory, there is evidence that the size of the preclinical deficit increases with increasing cognitive demands. The global cognitive impairment observed is highly consistent with observations that multiple brain structures and functions are affected long before the diagnosis of AD. However, there is substantial overlap in the distribution of cognitive scores between those who will and those who will not be diagnosed with AD, hence limiting the clinical utility of cognitive markers for early identification of cases. Future research should consider combining cognitive indicators with other types of markers (i.e. social, somatic, genetic, brain-based) in order to increase prediction accuracy.

The Impact of Childhood Intelligence on Later Life: Following Up the Scottish Mental Surveys of 1932 and 1947

The Scottish Mental Surveys of 1932 and 1947 collected valid IQ-type test scores for almost everyone born in 1921 and 1936 and attending school on June 1, 1932 (N=89,498) and June 4, 1947 (N=70,805). These surveys are described. This research, using the surveys' data, examined (a) the stability of intelligence differences across the life span, (b) the determinants of cognitive change from childhood to old age, and (c) the impact of childhood intelligence on survival and health in old age. Surviving participants of the Scottish Mental Surveys were tested, and the surveys' data were linked with public and health records. Novel findings on the stability of IQ scores from age 11 to age 80; sex differences in cognitive aging; the dedifferentiation hypothesis of cognitive aging; and the effect of childhood IQ on all-cause and specific mortality, morbidity, and frailty in old age are presented.

Modeling Memory Decline in Older Adults: The Importance of Preclinical Dementia, Attrition, and Chronological Age

This longitudinal study examined memory loss in a sample of 391 initially nondemented older adults. Analyses decomposed observed memory loss into decline associated with preclinical dementia, study attrition, terminal decline, and chronological age. Measuring memory as a function of only chronological age failed to provide an adequate representation of cognitive change. Disease progression accounted for virtually all of the memory loss in the 25% of the sample that developed diagnosable dementia. In the remainder of the sample, both chronological age and study attrition contributed to observed memory loss. These results suggest that much of memory loss in aging adults may be attributable to the progression of preclinical dementia and other nonnormative aging processes that are not captured by chronological age.

Rate of cognitive decline in preclinical Alzheimer's disease: the role of comorbidity

We investigated the influence of individual-difference variables implicated as risk factors for Alzheimer's disease (AD) or known to be related to cognitive performance in normal aging (e.g., age, sex, years of education, previous and recent diseases, apolipoprotein E status, social network, and substance use) on rate of cognitive change from preclinical to clinical AD. With the use of data from a population-based study, 230 persons who were nondemented at baseline and diagnosed with AD at a 3-year follow-up were examined with the Mini-Mental State Examination (MMSE). Of all predictor variables examined, only number of diseases resulting in hospital admission during the follow-up period made an independent contribution to rate of MMSE change. These results suggest that many variables affecting the onset of the degenerative process as well as cognitive functioning in normal aging exert little influence on rate of cognitive change in preclinical AD. This may reflect the fact that the emerging dementia disease overshadows the role of these variables for cognitive functioning. A possible exception to this pattern is that an increasing number of concomitant health conditions may exacerbate the rate of cognitive decline during the final portion of the preclinical phase in AD.

Cognitive deficits in preclinical Alzheimer's disease

We review the literature on cognitive functioning during the transition from normal aging to clinical Alzheimer's disease (AD). There is ample empirical evidence that deficits across multiple cognitive domains are apparent years to decades before the AD diagnosis, with impairments in episodic memory representing a common cognitive manifestation of the preclinical phase of the disease. Interestingly, the magnitude of the preclinical cognitive deficits appears to be relatively stable until a few years before clinical diagnosis. The behavioural deficits associated with preclinical AD are consistent with the neural changes that appear many years before eventual diagnosis. In addition to increasing our theoretical understanding of AD development, research on cognition in preclinical AD contributes to the identification of persons at risk of developing AD for purposes of intervention.

Terminal change in cognitive function: an updated review of longitudinal studies

We provide an update to Siegler's (1975) review of the terminal change literature. Articles identified through MEDLINE, CANCERLIT, PUBMED, and PSYCINFO from 1975 to 2000 were examined. Lower levels of cognitive function are related to increased risk of mortality; however, the relationship between rate of cognitive change and mortality is less clear. Although there has been an increase in the number of studies since our last review, prior studies have been limited by a lack of medical data, consideration of dementia, small sample sizes, and poor cognitive measures. The emphasis on Alzheimer's disease and the growth of epidemiology of aging in the past 25 years have provided well-characterized population studies with serial cognitive measures that provide an opportunity to test the theory of terminal change.

Cognitive screening and neuropsychological assessment in early Alzheimer's disease

Cognitive screening and detailed neuropsychological assessment provide a reliable means of detecting dementia in its earliest stages, tracking the progression of cognitive decline over time, and aiding in the differential diagnosis of various dementing disorders. In addition, recent studies have shown that mild cognitive changes, and particularly declines in memory function, are evident in the "preclinical" phase of Alzheimer's disease and may help to identify elderly individuals who are likely to develop dementia in the near future. Until effective and easily obtainable biological markers for detecting the onset and progression of Alzheimer's disease are developed, neuropsychological assessment will continue to have an important role in the dementia evaluation.

Alzheimer dementia in Down's syndrome: the relevance of cognitive ability

More years of education have been found to be associated with a lower rate of Alzheimer disease (AD) in individuals without intellectual disability. It has been proposed that education reflects greater 'synaptic reserve' and that greater synaptic reserve may defer the development of AD. The present study compared individuals with Down's syndrome (DS) who were found to have symptoms of dementia with those who remained symptom-free to determine if the two groups differed in their level of education, employment, recreational activities, years in an institution or overall level of cognitive functioning. Thirty-five adults with DS aged between 29 and 67 years were assessed. The participants were recruited from a community health facility and included individuals with a wide range of ability levels. Neuropsychological testing, caregiver report and the Dementia Scale for Down Syndrome (Gedye 1995) were used to identify decline in participants over periods of 6 months to 3 years. After the effect of age was statistically removed, multiple regression analyses revealed that level of cognitive functioning was significantly associated with decline such that a higher level of cognitive functioning predicted less decline. None of the environmental variables (i.e. educational level, years in an institution and employment) were directly associated with decline; however, a post hoc regression using level of cognitive functioning as the outcome variable revealed that level of cognitive functioning itself was associated with these environmental variables. A higher level of cognitive functioning was associated with fewer cases of dementia in individuals with DS, and level of cognitive functioning appears to be associated with environmental factors such as level of education, years in an institution and employment. The present findings suggest that environmental interventions aimed at improving level of cognitive functioning may also be useful in deferring the onset of dementia.

Does longer-term memory storage never become overloaded, and would such overload cause Alzheimer's disease and other dementia?

According to an uncritically accepted axiom, the human brain's capacity for longer-term memory storage is never overloaded. This viewpoint is shown to be contrary to all evidence and beyond reasonable credibility. The entire currently obtainable evidence for or against overload comes via the presence or absence of its manifestation in behaviour. This manifestation would be as an incurable, deteriorating, specific form of memory disorder, associated with old age and consequent to increased data-inputting and reductions of brain capacity. There is in fact such a disorder, namely Alzheimer's disease and other dementia. This relationship provides elegant explanations for various peculiar findings, without encountering any counter-evidence. The premorbid accumulation of tangles in the hippocampus is explained via an integration of existing hippocampus theories. Long-term low doses of drugs that reduce memory formation could prevent or delay dementia. TV-watching, videos, and some memory-enhancing nootropic drugs could increase risk.

Prodromal cognitive disorder in Alzheimer's disease

INTRODUCTION

To trace the prodromal evolution of Alzheimer's disease using a comprehensive computerized cognitive battery and an evaluation of performance of everyday activities.

MATERIALS AND METHODS

A general population cohort of 397 normal elderly persons hypothesized to have an increased risk of developing Alzheimer's disease was examined over a 3-year period. Twenty-two subjects developed AD in the third year and their performance was compared retrospectively with 150 subjects who had remained free of senile dementia and other psychiatric disorders throughout the period of the study.

RESULTS

Adjusting for effects of age, education and incident illness, significant differences were found between the two groups on a wide range of tests 2 years before diagnosis. For half of these tests the decline was largely limited to persons with low levels of education. Education effects closer to the time of diagnosis were limited to a small number of verbal tasks.

CONCLUSION

Patterns of cognitive impairment may be detected in cases of AD 2 years before formal clinical diagnosis, although high education level prolongs competence, principally on verbal tasks. The results suggest that a number of brief cognitive tests may have face validity and high discriminability independent of education level in the evaluation of cognitive complaints in early stage AD in the general practice setting.

Mild cognitive impairment--an early stage of Alzheimer's disease?

The hypothesis that mild cognitive impairment (MCI) represents an early stage of Alzheimer's disease (AD) was investigated by reviewing recent research from three sources: asymptomatic and symptomatic individuals carrying mutations that cause AD, hospital-samples of non-demented patients with MCI at the initial examination that are followed longitudinally, and community-based incident cases of AD. Studies with asymptomatic mutation carriers of the amyloid precursor protein and presenilin 1 gene have shown a linear and disease-related decline in most cognitive functions that begins approximately 10 years before the expected clinical onset of AD. However, there is considerable overlap between the level of impairment for mutation carriers and non-carriers of the same age during the early preclinical stage of AD. Hospital-based longitudinal studies have shown that non-demented individuals with isolated mild episodic memory impairment may develop clinically diagnosed AD with widespread cognitive deficits in a few years time. Community-based epidemiological studies on the incidence of AD demonstrate that indices of episodic memory, in addition to measures of general cognitive functioning, are useful in predicting early AD. In contrast, subjective memory impairment or age-associated memory impairment are less powerful predictors of future dementia development. In summary, there is converging evidence to demonstrate that preclinical AD is characterized by a common behavioral phenotype, with cognitive decline in several domains, predominantly in episodic memory. The decline appears to start many years before the clinical onset of AD. Moreover, the progression of the impairment appears to be continuous. Finally, this pattern of performance generalizes across etiology of AD (familial or sporadic), clinical onset (early or late), sample composition (hospital or community), and method of assessment.

Alzheimer's disease risk factors as related to cerebral blood flow: additional evidence

In a previous report, Alzheimer's disease risk factors, including alcohol abuse, depression, Down's syndrome, cerebral glucose metabolism defect, head trauma, old age, Parkinson's disease, sleep disturbance, and underactivity, were shown to have an association with reduced cerebral blood flow. In this report an attempt is made to strengthen a hypothesis that reduced cerebral blood flow may be a required cofactor in the cause of Alzheimer's disease with examples of additional putative risks, including aluminum, ApoE 4 alleles, estrogen deficiency, family history of dementia, low education-attainment, olfactory deficit, and underactivity coupled with gender, considered to have a relationship or potential relationship with reduced cerebral blood flow. Factors, believed to ameliorate Alzheimer's disease, associated with improved or stabilized cerebral blood flow are tabulated. A tentative cerebral blood flow nomogram is shown as a potential model to possibly help predict Alzheimer's disease susceptibility.

Cognitive markers preceding Alzheimer's dementia in the healthy oldest old

OBJECTIVE

To look for preclinical markers of Alzheimer's dementia in a sample of healthy, oldest old individuals.

DESIGN

Prospective, longitudinal study of individuals examined at yearly intervals with neuropsychological tests selected to be sensitive to the early detection of dementia.

PARTICIPANTS

One hundred and thirty-nine community-dwelling, functionally independent, healthy individuals 65 to 106 years of age who met strict criteria for lack of dementia at entry. Incident dementia cases consisted of 16 volunteers all 80 years old or older who developed dementia of the Alzheimer's type and 31 volunteers 80 years old and older showing no evidence of dementia during a mean 2.8-year follow-up interval.

MEASUREMENTS

Scores on 10 neuropsychological measures were analyzed for the initial examination when none of the volunteers showed clinical evidence of dementia and for the two subsequent yearly examinations.

RESULTS

Individuals who subsequently developed dementia showed evidence of verbal memory impairment at their initial examination, which was a mean of 2.8 years before clinical evidence of dementia. The average yearly incidence rate for dementia in those 80 years of age and older was 12%. Performance of individuals who did not development dementia remained relatively stable during follow-up for up to 5 years.

CONCLUSION

Alzheimer's disease has a preclinical stage in which verbal memory decline is the earliest sign. Dementia in the oldest old is distinguishable from age-related cognitive decline.

Alzheimer's disease risk factors as related to cerebral blood flow

Inconsistencies within results of case-control studies on Alzheimer's disease risk factors led to a search of the literature for a potential cofactor. Reduced cerebral blood flow was selected and literature was surveyed for evidence of a cerebral blood flow linkage with the more than 40 putative risks. Alcohol abuse, depression, head trauma, underactivity, old age, sleep disturbance, glucose utilization, Down's syndrome, and Parkinson's disease are risk factors where an association with reduced cerebral blood flow is documented. Studies were cited showing that improved cerebral blood flow is associated with factors thought to be helpful in Alzheimer's disease, such as education or occupational attainment, exercise, headache, smoking, and arthritis/anti-inflammatory drugs to the extent that aspirin is used. Sugar consumption is identified as a potential risk factor with glucose management in Alzheimer's disease also shown to involve reduced cerebral blood flow. An hypothesis is developed showing how compromised regional cerebral blood flow could fit as a cofactor for genetic, autoimmune, and neurotoxic aspects of Alzheimer's disease.

Cognitive changes in young-old adults: effect of family history of dementia

Cognitive performance of 40 first-degree relatives of patients with probable Alzheimer disease was compared to that of 24 matched controls without a family history of dementia. Across a test-retest interval ranging from 1 to 6 years, relatives more often showed evidence of cognitive decline, and in multivariate analyses of memory and intelligence measures, relatives of patients with early-onset dementia (< 67 years) showed greater decline than controls or relatives of patients with late-onset dementia. All changes observed to date are in the subclinical range, and further follow-up will be needed to determine the reliability of change trajectories. However, the findings suggest that family history of dementia may be worthy of monitoring in research on normal cognitive aging.

Cognitive deficits in asymptomatic first-degree relatives of Alzheimer's disease patients

The present study was designed to determine whether neuropsychological deficits exist in asymptomatic first-degree relatives of Alzheimer's disease (AD) patients. The neuropsychological performances of 20 first-degree asymptomatic relatives of NINCDS-ADRDA diagnosed AD patients were compared to 20 normal controls without family history of AD. Cognitive functions assessed included intelligence, memory, overall brain function, verbal learning, and language and constructional abilities. Significant statistical differences were found between the groups across several cognitive areas indicating lower functioning in the first-degree relatives of AD patients. Fifty percent of the first-degree subjects but only 20% of controls showed a pattern of significant neuropsychological deficit. The results demonstrate neuropsychological deficits in asymptomatic first-degree relatives of AD patients, suggesting that preclinical markers for AD may be present long before the clinical manifestation of the disease.

Disability in dementia: assessment, prevention, and rehabilitation

Dementia involves cognitive impairment sufficient to interfere with daily living. Most cases of dementia are due to Alzheimer's disease or cerebrovascular disease. Surveys show that dementia is one of the major causes of disability in the elderly, affecting personal care, everyday cognitive activities, and social behaviour. Several instruments relying on informant reports or behavioural observation have been developed to assess these various components of disability in dementia. Prevention of dementia would make a major contribution to the postponement of disability in old age. In principle, this could be achieved by modifying risk factors for Alzheimer's disease or vascular dementia. There is presently scope for the prevention of vascular dementia, but risk factors for Alzheimer's disease are not sufficiently understood. The paper discusses how, where dementia has already developed, programmes involving cognitive training or environmental redesign can help to maintain skills and reduce behavioural disturbances.