Natural history of mild cognitive impairment in older persons

Mild cognitive impairment and dementia

Mild cognitive impairment (MCI) is a clinical syndrome thought to represent the transition between normal function and dementia. This review describes data that support the existence of such a transitional phase, outlines the heterogeneity of MCI and how that has influenced the evolving concept of MCI, and discusses the impact of heterogeneity on recent MCI clinical trials.

Oxidatively modified RNA in mild cognitive impairment

Studies show increased oxidative damage in the brains of subjects with Alzheimer's disease (AD) and mild cognitive impairment (MCI). To determine if RNA oxidation occurs in MCI, sections of hippocampus/parahippocampal gyrus (HPG) from 5 MCI, 5 late stage AD (LAD) and 5 age-matched normal control (NC) subjects were subjected to immunohistochemistry using antibodies against 8-hydroxyguanine (8-OHG) and 1-N2-propanodeoxyguanosine (NPrG). Confocal microscopy showed 8-OHG and NPrG immunostaining was significantly (p<0.05) elevated in MCI and LAD HPG compared with NC subjects and was predominately associated with neurons identified using the MC-1 antibody that recognizes conformational alterations of tau, which are associated with early neurofibrillary tangle formation. Pretreating sections with RNase or DNase-I showed immunostaining for both adducts was primarily associated with RNA. In addition, levels of both adducts in MCI were comparable to those measured in LAD, suggesting RNA oxidation may be an early event in the pathogenesis of neuron degeneration in AD.

Estimation of the mediation effect with a binary mediator

A mediator acts as a third variable in the causal pathway between a risk factor and an outcome. In this paper, we consider the estimation of the mediation effect when the mediator is a binary variable. We give a precise definition of the mediation effect and examine asymptotic properties of five different estimators of the mediation effect. Our theoretical developments, which are supported by a Monte Carlo study, show that the estimators that account for the binary nature of the mediator are consistent for the mediation effect defined in this paper while other estimators are inconsistent. We use these estimators to study the mediation effect of chronic cerebral infarction in the causal relationship between the apolipoprotein E epsilon4 allele and cognitive function among 233 deceased participants from the Religious Orders Study, a longitudinal, clinical-pathologic study of aging and Alzheimer's disease.

Relationship of the Ubiquilin 1 gene with Alzheimer's and Parkinson's disease and cognitive function

Ubiquilin 1 (UBQLN1) is involved in the ubiquitination machinery, which has been implicated in Alzheimer's disease (AD) as well as Parkinson's disease (PD). A polymorphism in the gene encoding for UBQLN1 has been previously associated with a higher risk of AD. We studied the role of the SNP rs12344615 on the UBQLN 1 gene in AD, PD and cognitive function in a population-based study, the Rotterdam Study, and a family-based study embedded in the genetic research in isolated population (GRIP) program. The Rotterdam Study includes 549 patients with AD and 157 patients with PD. The GRIP program includes a series of 123 patients with AD and a study of 1049 persons who are characterized for cognitive function. Data were analysed using logistic and multiple regression analysis. We found no significant difference in risk of AD or PD by the UBQLN1 SNP rs12344615 in our overall and stratified analyses in the Rotterdam Study. In our family-based study, we did not find evidence for linkage of AD to the region including the UBQLN1 gene. In the family-based study we also failed to detect an effect of this polymorphism on cognitive function. Our results suggest that it is unlikely that the SNP rs12344615 of the UBQLN1 gene is related to the onset of AD, PD or cognitive function.

Mini-mental State Examination performance in mild cognitive impairment subtypes

BACKGROUND

Diagnosis of mild cognitive impairment (MCI) and its subtypes requires a detailed diagnostic assessment and so may be missed at routine primary-care appointments, since the ordinary dementia screening tests lack sensitivity owing to ceiling effects, especially in highly educated subjects.

METHODS

The study was undertaken using a cross-sectional assessment of 112 elderly subjects (mean age 67.96+/-5.77 years, and mean education level of 12.8+/-5.7 years) with a semi-structured interview and a neuropsychological battery.

RESULTS

MCI patients did not differ from controls on total MMSE scores (p=0.212). Nevertheless, MCI patients showed worse performance than controls on the verbal memory task (p=0.012), and "drawing a pentagon" (p=0.03). Amnestic MCI patients performed worse only on the "three-word recall" task (p=0.013); non-amnestic MCI patients performed worse on the "three-stage command" task (p=0.001); and multiple-domain MCI patients performed worse on the "drawing a pentagon" task (p=0.001) and had a trend toward performing poorly on the 'three word recall' task (p=0.06).

CONCLUSION

The analysis of MMSE subtest scores, in addition to MMSE total scores, may increase the sensitivity of the MMSE test in screening for MCI and its subtypes.

Modifying effects of the HFE polymorphisms on the association between lead burden and cognitive decline

BACKGROUND

As iron and lead promote oxidative damage, and hemochromatosis (HFE) gene polymorphisms increase body iron burden, HFE variant alleles may modify the lead burden and cognitive decline relationship.

OBJECTIVE

Our goal was to assess the modifying effects of HFE variants on the lead burden and cognitive decline relation in older adults.

METHODS

We measured tibia and patella lead using K-X-ray fluorescence (1991-1999) among participants of the Normative Aging Study, a longitudinal study of community-dwelling men from greater Boston. We assessed cognitive function with the Mini-Mental State Examination (MMSE) twice (1993-1998 and 1995-2000) and genotyped participants for HFE polymorphisms. We estimated the adjusted mean differences in lead-associated annual cognitive decline across HFE genotype groups (n = 358).

RESULTS

Higher tibia lead was associated with steeper cognitive decline among participants with at least one HFE variant allele compared with men with only wild-type alleles (p interaction = 0.03), such that a 15 microg/g increase in tibia lead was associated with a 0.2 point annual decrement in MMSE score among HFE variant allele carriers. This difference in scores among men with at least one variant allele was comparable to the difference in baseline MMSE scores that we observed among men who were 4 years apart in age. Moreover, the deleterious association between tibia lead and cognitive decline appeared progressively worse in participants with increasingly more copies of HFE variant alleles (p-trend = 0.008). Results for patella lead were similar.

CONCLUSION

Our findings suggest that HFE polymorphisms greatly enhance susceptibility to lead-related cognitive impairment in a pattern consistent with allelelic dose.

Imaging markers of mild cognitive impairment: Multivariate analysis of CBF SPECT

This study aimed to investigate cross-sectional and longitudinal changes of regional cerebral blood flow (rCBF) in preclinical dementia using single photon emission computed tomography (SPECT). SPECT and cognitive function were investigated in 39 mild cognitive impairment (MCI) subjects and 20 age-matched controls. All subjects were followed longitudinally 19 months on average, 16 MCI subjects progressed to Alzheimer's disease (AD), who were retrospectively defined as progressive mild cognitive impairment (PMCI) at baseline and 23 MCI subjects remained stable and were defined as stable mild cognitive impairment (SMCI) at baseline. SPECT was performed both at the initial investigation and at follow-up. Image data were analyzed using multivariate analysis, SPM and volume of interest (VOI)-based analysis. Significant covariate patterns were derived, which differentiate among PMCI, SMCI and controls at baseline as well as describe the longitudinal progression of PMCI. The combined SPECT and neuropsychology increased the diagnostic accuracy of PMCI at baseline. SPECT and neuropsychological testing can be used objectively for both baseline diagnosis and to monitor changes in brain function during very early AD.

Chronic distress and incidence of mild cognitive impairment

OBJECTIVE

Mild cognitive impairment (MCI) is associated with increased morbidity and mortality but its development is not well understood. Here we test the hypothesis that chronic psychological distress is associated with increased incidence of MCI in old age.

METHODS

Participants are older persons from two cohort studies with uniform annual clinical evaluations which included detailed cognitive testing and clinical classification of MCI. We excluded persons with dementia or MCI at baseline; follow-up data were available on 1,256 persons without cognitive impairment (95% of those eligible). At baseline, they completed a six-item measure of neuroticism (mean = 15.6, SD = 6.6), an indicator of the tendency to experience psychological distress.

RESULTS

During up to 12 years of follow-up, 482 persons (38%) developed MCI. Risk of MCI increased by about 2% for each one unit increase on the distress scale (relative risk [RR] = 1.02; 95% CI: 1.01, 1.04), with the association slightly stronger in men than women. Overall, a distress-prone person (score = 24, 90th percentile) was about 40% more likely to develop MCI than someone not prone to distress (score = 8, 10th percentile). Adjustment for depressive symptomatology at baseline did not substantially change results (RR = 1.02; 95% CI: 1.00, 1.03). Depressive symptoms were also related to risk of MCI but not after controlling for distress score. In mixed-effects models, higher distress score was associated with lower level of function in multiple cognitive domains at baseline and more rapid cognitive decline, especially in episodic memory.

CONCLUSION

Among older persons without manifest cognitive impairment, higher level of chronic psychological distress is associated with increased incidence of mild cognitive impairment.

Conversion to dementia from questionable dementia in an ethnic Chinese population

We investigated the conversion rate and the risk factors for conversion to dementia from questionable dementia in 124 ethnic Chinese subjects with questionable dementia at a memory clinic of a university hospital. They were evaluated annually based on cognitive testing, the clinical dementia rating scale, and a psychiatrist's interview for depression and anxiety. Apolipoprotein E genotyping was performed on 111 of these questionable dementia subjects. All subjects were evaluated at least twice during the follow-up period of 20.4 +/- 12.4 months. During that period, 42 questionable dementia subjects were diagnosed as having Alzheimer's disease, with an annual conversion rate to dementia of 19.9%. Compared with the 82 nonconverters, the 42 converters were significantly older, had lower cognitive, depression, and anxiety scores, and a higher frequency of the apolipoprotein E epsilon4 allele. Cox regression analysis revealed that the Alzheimer's disease converters had lower scores for orientation, short-term memory, and anxiety, and a higher frequency of the apolipoprotein E epsilon4 allele than the nonconverters.

Transitions to mild cognitive impairments, dementia, and death: findings from the Nun Study

The potential of early interventions for dementia has increased interest in cognitive impairments less severe than dementia. However, predictors of the trajectory from intact cognition to dementia have not yet been clearly identified. The purpose of this study was to determine whether known risk factors for dementia increased the risk of mild cognitive impairments or progression from mild cognitive impairments to dementia. A polytomous logistic regression model was used, with parameters governing transitions within transient states (intact cognition, mild cognitive impairments, global impairment) estimated separately from parameters governing the transition from transient to absorbing state (dementia or death). Analyses were based on seven annual examinations (1991-2002) of 470 Nun Study participants aged > or = 75 years at baseline and living in the United States. Odds of developing dementia increased with age primarily for those with low educational levels. In these women, presence of an apolipoprotein E gene *E4 allele increased the odds more than fourfold by age 95 years. Age, education, and the apolipoprotein E gene were all significantly associated with mild cognitive impairments. Only age, however, was associated with progression to dementia. Thus, risk factors for dementia may operate primarily by predisposing individuals to develop mild cognitive impairments; subsequent progression to dementia then depends on only time and competing mortality.

Lower Extremity Motor Function and Disability in Mild Cognitive Impairment

Recent findings suggest that lower extremity motor dysfunction may be a feature of mild cognitive impairment (MCI), but little is known about the nature and significance of lower extremity motor dysfunction in MCI. The aim of this study was to examine the extent to which MCI is associated with impaired gait, balance, and strength and to examine the relation of lower extremity function to disability among persons with MCI in the Rush Memory and Aging Project, a clinical-pathologic study of common chronic conditions of old age. In a series of analyses adjusted for age, sex, and education, individuals with MCI exhibited more impaired gait and balance than individuals without cognitive impairment. Because vascular factors can contribute to lower extremity motor dysfunction, the authors repeated the initial analyses including terms for vascular risk factors and vascular disease, and the associations between MCI and lower extremity motor dysfunction persisted. Moreover, among those with MCI, impairments in gait and balance were associated with an increased likelihood of disability. These findings suggest that lower extremity motor dysfunction is common and contributes to disability in MCI, but lower extremity motor dysfunction in MCI does not appear to be explained by the vascular factors examined in this study.

Activation of caspase-6 in aging and mild cognitive impairment

Active caspase-6 (Csp6) and Tau cleaved by Csp6 (TauDeltaCsp6) are abundant in neuritic plaques (NPs), neuropil threads (NPTs), and neurofibrillary tangles (NFTs) in end-stage Alzheimer's disease (AD) (Guo H, Albrecht S, Bourdeau M, Petzke T, Bergeron C, LeBlanc AC: Active caspase-6 and caspase-6 cleaved Tau in neuropil threads, neuritic plaques and neurofibrillary tangles of Alzheimer's disease. Am J Pathol 2004, 165:523-531). The goal of this study was to determine whether active Csp6 is present in young and aged noncognitively impaired (NCI); aged mild cognitively impaired (MCI); and aged mild, moderate, severe, and very severe AD individuals. Csp6 activity was assessed with anti-p20Csp6 and TauDeltaCsp6 immunoreactivity. Active Csp6 is present in NFTs, NPTs, and NPs at all stages of AD. Active Csp6 is present in NFTs of all MCI cases and present in NPTs and NPs of some MCI cases. Active Csp6 is present in NFTs and NPTs of all NCI cases but is absent in younger cases. The level of TauDeltaCsp6-positive NFTs and NPTs correlates inversely with global cognitive scores in NCI individuals. Therefore, Csp6 activity can occur with aging in the absence of AD and is always associated with clinical and pathological features of confirmed AD cases. Given the ability of active Csp6 to increase amyloid-beta peptide production and cleave Tau and several synaptic proteins (LeBlanc AC, Liu H, Goodyer C, Bergeron C, Hammond J: Caspase-6 role in apoptosis of human neurons, amyloidogenesis and Alzheimer's disease. J Biol Chem 1999, 274:23426-23436; Petzke TL, Rousselet E, Goodyer C, LeBlanc AC: Substrates of caspase-6 in human primary neurons: a proteomic study. Program No. 80.9. 2005 Abstract Viewer/Itinerary Planner. Washington, DC: Society for Neuroscience. Online), we suggest that active Csp6 could be an early instigator of neuronal dysfunction.

Brain erythropoietin receptor expression in Alzheimer disease and mild cognitive impairment

Cellular mechanisms conferring neuroprotection in the brains of patients with Alzheimer disease (AD) remain incompletely understood. Erythropoietin (Epo) and the erythropoietin receptor (EpoR) are expressed in neural tissues and protect against oxidative and other stressors in various models of brain injury and disease. Our objective in this study was to determine whether EpoR is upregulated in the brains of persons with sporadic AD and mild cognitive impairment (MCI). Postmortem hippocampus and temporal cortex from subjects with AD, MCI, and no cognitive impairment (NCI) were procured from the Religious Orders Study. Total immunoreactive EpoR protein was determined by Western blotting. Astrocytes expressing immunoreactive EpoR were quantified in 4 temporal and 6 hippocampal regions, and correlated with clinical, neuropsychologic, and neuropathologic indices. Total immunoreactive EpoR protein was markedly increased in AD and MCI temporal cortex versus NCI tissues. Composite measures of glial EpoR expression in temporal cortex layers I to IV were significantly greater in the MCI group compared with the NCI and AD groups. Hippocampal EpoR scores were increased in persons with MCI and AD relative to those with NCI. There was substantial subregional heterogeneity in disease-related EpoR expression patterns in AD and MCI temporal cortex and hippocampus. There was no association of EpoR-positive astrocytes with summary measures of global cognition or AD pathology. We conclude that upregulation of EpoR in temporal cortical and hippocampal astrocytes is an early, potentially neuroprotective, event in the pathogenesis of sporadic AD.

Clinical and neuropsychological features associated with structural imaging patterns in patients with mild cognitive impairment

AIM

To describe the clinical and neuropsychological features of mild cognitive impairment (MCI) patients with medial temporal atrophy (MTA), white matter hyperintensities (WMH), both, and neither and to assess whether the rate of progression differs among groups.

METHODS

Ninety-five MCI patients were divided into 4 groups based on the presence of MTA and WMH: 29 were MTA- WMH-, 11 MTA- WMH+, 23 MTA+ WMH-, and 32 MTA+ WMH+. MCI patients were compared with 30 normal subjects. MTA and WMH were assessed with MR-based visual rating scales. Subjects underwent an extensive clinical and neuropsychological investigation. Fifty-six underwent follow-up evaluation.

RESULTS

MTA- WMH- had relatively good neuropsychological performance, little vascular and physical comorbidity. MTA- WMH+ performed poorly only on executive neuropsychological tests. MTA+ WMH- patients had poor neuropsychological performances (mainly on memory tests), high physical and vascular comorbidity. MTA+ WMH+ were impaired in neuropsychological performances, had a high number of physical diseases and severe vascular comorbidity. On follow-up, 25% of MTA+ WMH- and 32% of MTA+ WMH+ and none in MTA- WMH- and in MTA- WMH+ converted to dementia (p = 0.05, log rank test).

CONCLUSION

Structural neuroimaging can identify subgroups of MCI patients with specific clinical and neuropsychological features.

Cell division in the CNS: protective response or lethal event in post-mitotic neurons?

Cell cycle events have been documented to be associated with several human neurodegenerative diseases. This review focuses on two diseases--Alzheimer's disease and ataxia telangiectasia--as well as their mouse models. Cell cycle studies have shown that ectopic expression of cell cycle markers is spatially and regional correlated well with neuronal cell death in both disease conditions. Further evidence of ectopic cell cycling is found in both human diseases and in its mouse models. These findings suggest that loss of cell cycle control represents a common pathological root of disease, which underlies the defects in the affected brain tissues in both human and mouse. Loss of cell cycle control is a unifying hypothesis for inducing neuronal death in CNS. In the disease models we have examined, cell cycle markers appear before the more well-recognized pathological changes and thus could serve as early stress markers--outcome measures for preclinical trials of potential disease therapies. As a marker these events could serve as a new criterion in human pathological diagnosis. The evidence to date is compatible with the requirement for a second "hit" for a neuron to progress cell cycle initiation and DNA replication to death. If this were true, any intervention of blocking 'second' processes might prevent or slow the neuronal cell death in the process of disease. What is not known is whether, in an adult neuron, the cell cycle event is part of the pathology or rather a desperate attempt of a neuron under stress to protect itself.

Dementia syndromes: evaluation and treatment

As our population ages, diseases affecting memory and daily functioning will affect an increasing number of individuals, their families and the healthcare system. The social, financial and economic impacts will be profound. This article provides an overview of current dementia syndromes to assist clinicians in evaluating, educating and treating these patients.

Problem Solving Ability in Patients With Mild Cognitive Impairment

BACKGROUND AND OBJECTIVE

It is important to determine which patients with mild cognitive impairment (MCI) are at risk for progression to dementia. The presence of mild impairments not restricted to the domain of memory may suggest such progression. Our goal is to determine how well a visuospatial problem solving task assessing the cumulative burden of frontal and posterior damage differentiates MCI patients from matched controls.

METHODS

Twenty-six patients with MCI [Clinical Dementia Rating (CDR) score of 0.5] and mini-mental state examination (MMSE) scores of at least 24/30, were compared with 20 age and education level matched controls without cognitive impairment. All patients were given the MMSE, Hopkins Verbal Learning Test (HVLT), Boston Naming Test (BNT), Rey Complex Figures copying (RCF), anagrams, and visuospatial problem solving battery (VPS). The VPS is a complex problem solving task, which we predicted would better discriminate patient groups than the relatively simpler tasks.

RESULTS

Differences existed between groups on most tasks, but logistic regression revealed that the VPS discriminated the 2 groups better than the other nonmemory cognitive tests.

CONCLUSIONS

The VPS, a problem solving task assessing the cumulative burden of frontal and posterior damage is more sensitive for detecting nonmemory impairments in MCI than other tasks. Future research will be needed to determine if impairment in the VPS is a sensitive predictor of progression to dementia or treatment response.

Cases with Mild Cognitive Impairment and Alzheimer’s Disease Fail to Benefit from Repeated Exposure to Episodic Memory Tests as Compared with Controls

Memory tests may be predictive for cognitive decline. We investigated the sensitivity and change in performance over time of the Hopkins Verbal Learning Test (HVLT) and the Mini-Mental Status Examination (MMSE) for Mild Cognitive Impairment (MCI) and Alzheimer's Disease (AD) when compared to cognitively healthy controls. Participants included elderly controls (n = 54), MCI (n = 19) and AD cases (n = 28) from OPTIMA. The MMSE and the HVLT (version 1) were administered twice to all subjects with an interval of 2-3 years.MCI and AD cases had poorer performance than controls on the HVLT and MMSE at both testing episodes (p < 0.05). The HVLT profile over time showed a learning effect in the control group (P < 0.0001), a trend to decline in the AD group (p = 0.09) and no change in the MCI group (P = 0.8). A subgroup of MCI subjects had lower HVLT scores at follow-up. The MMSE profile showed no significant change over time for all three groups (P > 0.05). The HVLT had better sensitivity and specificity compared to the MMSE for detecting MCI and AD. The HVLT is not only valuable for cross-sectional designs but has also proved to be valuable in a longitudinal design. Cognitively healthy controls showed evidence of learning strategies on the HVLT after a 2-3 year interval, with improved scores at the second testing episode. By contrast, an MCI group showed no benefits of previous exposure to this test. Lack of use of learning strategies on the HVLT may be an important marker of the likelihood of cognitive decline to MCI or dementia.

Terminal cognitive decline: accelerated loss of cognition in the last years of life

OBJECTIVE

To test the hypothesis that rate of cognitive decline accelerates in the last years of life.

METHODS

Participants are 853 older persons without dementia at study onset. For up to 8 years, they underwent annual clinical evaluations that included a battery of 19 cognitive tests from which previously established composite measures of global cognition and specific cognitive domains were derived. In analyses, we used linear mixed-effects models that allowed rate of cognitive decline to change at a given point before death to estimate the onset of a terminal decline period and rate of cognitive decline before and after that point. In subsequent analyses, we tested potential modifiers of terminal decline.

RESULTS

There were 115 deaths. Those who died did not differ from survivors in their level of global cognitive function at study onset, but beginning a mean of 42 months before death, their rate of global cognitive decline sharply increased. The duration and rapidity of terminal decline in global cognition differed from person to person. Terminal cognitive decline was not modified by age, sex, education, or the presence of mild cognitive impairment, but it was not present in those with vascular disease (e.g., stroke and heart attack) or in those without at least one copy of the apolipoprotein E epsilon4 allele, suggesting that Alzheimer's disease pathology may contribute to the phenomenon.

CONCLUSIONS

In old age, cognitive decline markedly accelerates during the last 3 to 4 years of life, consistent with the terminal decline hypothesis.

Chronic distress, age-related neuropathology, and late-life dementia

OBJECTIVE

The objective of this study was to test whether common age-related neuropathology could account for the relation of chronic distress to dementia.

METHODS

In a selected cohort of more than 1000 older Catholic clergy members undergoing annual clinical evaluations, 326 persons died, of whom 306 (94%) underwent brain autopsy, the results of which were available in 219 (mean age at death = 85.4, standard deviation [SD] = 6.6; mean postmortem interval = 7.6 hours, SD = 6.9). A composite measure of chronic distress was constructed from standard measures of two traits, neuroticism and anxiety proneness, completed at baseline, and of depressive symptoms, completed annually. Dementia was diagnosed according to standard criteria and cognition was assessed with previously established composite measures based on a uniform clinical evaluation that took place a mean of 9.1 months before death (SD = 9.5). On postmortem examination, levels of amyloid-beta and tau-positive neurofibrillary tangles and the presence of Lewy bodies were quantified in six brain regions, and the number and location of chronic cerebral infarctions were noted.

RESULTS

In analyses that controlled for age, sex, education, amyloid, tangles, Lewy bodies, and cerebral infarction, higher level of chronic distress was associated with a higher likelihood of dementia and lower level of cognition proximate to death. Chronic distress was not correlated with any form of neuropathology, including limbic, neocortical, and global indices, and did not modify the association of pathology with cognition.

CONCLUSIONS

Chronic psychological distress is associated with late-life dementia but not with its leading causes, suggesting that novel neurodeteriorative mechanisms may be involved.

Validation Study of the Three-Objects-Three-Places Test: A Screening Test for Alzheimer's Disease

The aim of the present study was to validate a short, ecological test of episodic memory for the screening of Alzheimer's disease (AD). The validation was performed by computing intrarater reliability, homogeneity, internal coherence, convergent, discriminant and known group validities in the performance of normal subjects (N = 65), mild cognitive impairment (MCI) patients (N = 114), and AD (N = 44) and non-AD demented (N = 39) patients. Intrarater reliability was 0.88, homogeneity ranged from 0.81 to 0.97, and internal coherence was 0.87. With respect to convergent and discriminant validities, the test loaded strongly on memory factor (value = 0.64) and weakly on other nonmemory factors. The known group validity showed a specificity between 87% and 91% and a sensitivity between 92% and 100% in correctly identifying AD in age classes ranging from 50 to 65 and 66 to 80 years. The test is a valid instrument for the screening of AD.

Combining olfaction and cognition measures to screen for mild cognitive impairment

PURPOSE

This exploratory study examined the relationship between performance on the University of Pennsylvania Smell Identification Test (UPSIT) and the Addenbrooke's Cognitive Examination (ACE) to identify a possible association between olfaction and mild cognitive impairment(MCI).

DESIGN AND METHODS

54 community-dwelling older (ages 49-91) volunteers were given the UPSIT and ACE.

RESULTS

The ACE identified 7 subjects (13%) who had probable MCI. UPSIT total scores were significantly related to ACE total scores (r = 0.37, p = 0.005). Four specific odorants (mint, lime, chocolate, and cheddar cheese) from the UPSIT identified 4 of the 7 (57.1%) probable MCI subjects. The prevalence rate of MCI in subjects over 65 was 19.4%.

IMPLICATIONS

Selective odorants in UPSIT used with ACE show promise as a non-invasive method of detecting MCI in community dwelling elders. Detection of MCI could facilitate earlier interventions and treatment of dementia.

Postmortem indices linking risk factors to cognition: results from the Religious Order Study and the Memory and Aging Project

We present data from the Religious Orders Study and the Memory and Aging Project linking risk factors to pathology and cognitive function. Both studies involve more than 1000 older persons who agreed to annual clinical evaluation and brain donation at death. Published findings from the studies to date suggest that the relationship between risk factors, pathology, and cognitive impairment is complex. In some cases, known neuropathologic indices mediate the association of risk factors to cognition. In other cases, risk factors modify the relation of pathology to cognition. Finally, some risk factors seem to be related to clinical Alzheimer disease and cognitive decline, even decline in episodic memory, in the absence of any association with amyloid plaques, neurofibrillary tangles, or other pathologic indices that can be identified and quantified at this time. The findings to date illustrate the kinds of insights that can be gained into mechanisms of disease through the incorporation of pathologic indices into well-designed, epidemiologic studies of aging and Alzheimer disease.

Mild cognitive impairment and the 7 uses of epidemiology

In 1907, Alzheimer's single case report of presenile dementia led to the condition being recognized as a rare disease of middle-aged people. In 1964, Roth and colleagues reported an epidemiologic survey showing that the same condition was in fact a relatively common disease of the elderly. In 1987, Katzman introduced the concept of brain reserve, suggesting how individuals could have Alzheimer disease pathology in their brains without clinically manifesting the disease. In 1999, Petersen described mild cognitive impairment (MCI) as an amnestic state, since broadened to include other cognitive deficits, which, in the majority of patients, was a prelude to the development of full-blown Alzheimer disease or other dementia. MCI today is in some ways analogous to Alzheimer disease a century ago. We recognize and describe MCI clinically, among patients with memory complaints, but we do not know its distribution, outcomes, and risk factors in the elderly population at large. All population-based studies to date have found MCI to be an unstable and heterogeneous entity with a far wider range of outcomes than in the clinical setting, including reversion to normal in a substantial proportion. However, these studies thus far have been purely descriptive, and retro-fitted on to existing studies of dementia, using measurements not necessarily appropriate for the assessment of MCI. This review will address what is known and what has yet to be determined about MCI from the perspectives of the classic 7 uses of epidemiology.

DNA oxidation in Alzheimer's disease

Oxidative damage to DNA may play an important role in aging and neurodegenerative diseases such as Alzheimer's disease (AD). Attack on DNA by reactive oxygen species, particularly hydroxyl radicals, can lead to strand breaks, DNA-DNA and DNA-protein cross-linking, sister chromatid exchange and translocation, and formation of at least 20 oxidized base adducts. Modification of DNA bases can lead to mutation and altered protein synthesis. In late-stage AD brain, several studies have shown an elevation of the base adducts 8 hydroxyguanine (8-OHG), 8-hydroxyadenine (8-OHA), 5-hydroxycytosine (5-OHC), and 5-hydroxyuracil, a chemical degradation product of cytosine. Several studies have shown a decline in repair of 8-OHG in AD. Most recently, our studies have shown elevated 8-OHG, 8-OHA, and 5,6-diamino-5-formamidopyrimidine in nuclear and mitochondrial DNA in mild cognitive impairment, the earliest detectable form of AD, suggesting that oxidative damage to DNA is an early event in AD and not a secondary phenomenon.

Medial temporal atrophy but not memory deficit predicts progression to dementia in patients with mild cognitive impairment

BACKGROUND

The diagnosis of mild cognitive impairment (MCI) is clinically unhelpful, as many patients with MCI develop dementia but many do not.

OBJECTIVE

To identify clinical instruments easily applicable in the clinical routine that might be useful to predict progression to dementia in patients with MCI assessed in the outpatient facility of a memory clinic.

PARTICIPANTS AND METHODS

52 dementia-free patients (mean (standard deviation) age 70 (6) years; 56% women) with MCI, and 65 healthy controls (age 69 (6) years; 54% women) underwent brain magnetic resonance scan with standardised visual assessment of medial temporal atrophy (MTA) and subcortical cerebrovascular lesions (SVLs). Follow-up assessment occurred 15.4 (SD 3.4) months after baseline to detect incident dementia and improvement, defined as normal neuropsychological performance on follow-up.

RESULTS

Patients were classified into three groups according to the presence of memory disturbance only (MCI Mem), other neuropsychological deficits (MCI Oth) or both (MCI Mem+). MCI Mem and Mem+ showed MTA more frequently (31% and 47% v 5% and 14% of controls and MCI Oth, p<0.001). 11 patients developed dementia (annual rate 16.5%) and 7 improved on follow-up. The only independent predictor of progression was MTA (odds ratio (OR) 7.1, 95% confidence interval (CI) 1.4 to 35.0), whereas predictors of improvement were the absence of memory impairment (OR 18.5, 95% CI 2.0 to 171.3) and normal MRI scan (OR 10.0, 95% CI 1.7 to 60.2).

CONCLUSION

Neuropsychological patterns identify groups of patients with MCI showing specific clinical features and risk of progression to dementia. MTA clinically rated with a visual scale is the most relevant predictor of progression and improvement.

Decision rules guiding the clinical diagnosis of Alzheimer's disease in two community-based cohort studies compared to standard practice in a clinic-based cohort study

We developed prediction rules to guide the clinical diagnosis of Alzheimer's disease (AD) in two community-based cohort studies (the Religious Orders Study and the Rush Memory and Aging Project). The rules were implemented without informant interviews, neuroimaging, blood work or routine case conferencing. Autopsies were performed at death and the pathologic diagnosis of AD made with a modified version of the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) criteria. We compared the positive predictive value of the clinical diagnosis in the two community-based studies to the positive predictive value of the clinical diagnosis of AD made by standard clinical practice in a clinic-based cohort study using AD pathology as the gold standard. Of 306 clinic cases with probable AD, 286 (93.5%) met CERAD neuropathologic criteria for AD; the results were comparable for those with possible AD (51 of 54, 94.4%). Of 141 study subjects with probable AD, 130 (92.2%) met CERAD neuropathologic criteria for AD; the results were lower but acceptable for those with possible AD (26 of 37, 70.3%). The results were similar in secondary analyses using alternate neuropathologic criteria for AD. The clinical diagnosis of AD can be made in community-based studies without the use of informant interviews, neuroimaging, blood work or routine case conferencing. This approach holds promise for reducing the operational costs of epidemiologic studies of aging and AD.

Is mild cognitive impairment a distinct clinical entity?

Mild cognitive impairment is a syndrome characterized by significant cognitive deficits in the absence of dementia. Persons with mild cognitive impairment have a high risk of developing Alzheimer’s disease and other dementias. However, opinion on whether mild cognitive impairment is a prodromal phase of Alzheimer’s disease and should be treated is divided. The first part of this article will address some of the controversies in mild cognitive impairment on which most researchers have now reached an agreement. Second, we will discuss some of the remaining major controversies in the field, and suggest some avenues for future research. The article will focus around two questions: Is mild cognitive impairment a distinct clinical entity and should it be treated as Alzheimer’s disease?

Blood pressure and lower limb function in older persons

BACKGROUND

Factors contributing to gait difficulties in elderly persons are considered to be multifactorial and are not well understood. The purpose of this study was to examine the association of blood pressure (BP) with change in lower limb function in older persons.

METHODS

Eight hundred eighty-eight older Catholic clergy members without baseline dementia or Parkinson's disease were recruited from about 40 groups across the United States. At baseline, BP was measured, the presence of vascular diseases and diabetes was recorded, cognitive function was assessed, and medications were inspected. At baseline and subsequent annual visits, gait and balance were assessed using performance-based tasks from which a previously established composite measure of lower limb function was derived.

RESULTS

In a general estimating equation analysis controlling for age, education, and gender, a 10 mmHg increment in systolic blood pressure (SBP) was associated with greater decline in lower limb function (estimate of interaction = -6.35 x 10(-3), standard error = 2.49 x 10(-3), p =.011). Thus, on average, lower limb function declined 28.7% faster in persons with an SBP of 160 mmHg than in persons with an SBP of 120 mmHg. This effect was unchanged after controlling for baseline vascular diseases, diabetes, or cognition. However, censoring individuals who developed stroke during the study made the relationship between SBP and change in lower limb function nonsignificant.

CONCLUSIONS

SBP may be associated with decline in lower limb function in older persons.

Galanin fiber hypertrophy within the cholinergic nucleus basalis during the progression of Alzheimer's disease

Galanin (GAL)-containing fibers enlarge and hyperinnervate remaining cholinergic basal forebrain (CBF) neurons within the anterior nucleus basalis (NB) in late-stage Alzheimer's disease (AD). Whether GAL hypertrophy occurs in the CBF in the prodromal or early stages of AD remains unknown. The present study used GAL immunohistochemistry and an unbiased semiquantitative scoring method to evaluate GAL innervation in the anterior NB of subjects clinically diagnosed as having no cognitive impairment, mild cognitive impairment or early-stage (mild/moderate) AD. There was no difference in GAL fiber staining within the anterior NB across the three clinical groups examined. Furthermore, GAL fiber innervation was not correlated with the number of NB neurons expressing the nerve growth factor receptors p75(NTR) or TrkA or with cortical choline acetyltransferase activity in the same cases. Single-cell gene expression analysis demonstrated that cholinergic NB neurons express mRNA for the GAL receptors GALR1, GALR2 and GALR3, yet the levels of these mRNAs were unchanged across the three diagnostic groups. These observations indicate that GAL hypertrophy within the anterior NB subfield is a late-stage AD response, which may play a role in regulating the cholinergic tone of remaining basocortical projection neurons.

Single cell gene expression profiling in Alzheimer's disease

Development and implementation of microarray techniques to quantify expression levels of dozens to hundreds to thousands of transcripts simultaneously within select tissue samples from normal control subjects and neurodegenerative diseased brains has enabled scientists to create molecular fingerprints of vulnerable neuronal populations in Alzheimer's disease (AD) and related disorders. A goal is to sample gene expression from homogeneous cell types within a defined region without potential contamination by expression profiles of adjacent neuronal subpopulations and nonneuronal cells. The precise resolution afforded by single cell and population cell RNA analysis in combination with microarrays and real-time quantitative polymerase chain reaction (qPCR)-based analyses allows for relative gene expression level comparisons across cell types under different experimental conditions and disease progression. The ability to analyze single cells is an important distinction from global and regional assessments of mRNA expression and can be applied to optimally prepared tissues from animal models of neurodegeneration as well as postmortem human brain tissues. Gene expression analysis in postmortem AD brain regions including the hippocampal formation and neocortex reveals selectively vulnerable cell types share putative pathogenetic alterations in common classes of transcripts, for example, markers of glutamatergic neurotransmission, synaptic-related markers, protein phosphatases and kinases, and neurotrophins/neurotrophin receptors. Expression profiles of vulnerable regions and neurons may reveal important clues toward the understanding of the molecular pathogenesis of various neurological diseases and aid in identifying rational targets toward pharmacotherapeutic interventions for progressive, late-onset neurodegenerative disorders such as mild cognitive impairment (MCI) and AD.

Mild cognitive impairment should be considered for DSM-V

Mild cognitive impairment is a topic of great activity from both clinical and research perspectives. It represents a transitional state between the cognitive changes of aging and the earliest clinical manifestations of dementia. We present a case for its inclusion in the Diagnostic and Statistical Manual of Mental Disorders (5th ed; DSM-V) based on clinical, outcome, epidemiological, neuroimaging, and pathophysiological data. The strongest case for inclusion can be made for the amnestic subtype, which is likely a clinical precursor of Alzheimer's disease. Arguments are presented as to why mild cognitive impairment can be considered as an entity distinct from normal aging and from clinically probable Alzheimer's disease and why it deserves consideration as a separate construct. In many respects, mild cognitive impairment fulfills criteria for inclusion more adequately than many other conditions currently codified in DSM-IV. Future research directions to help clarify some of the remaining uncertainties are proposed.

Myths and Realities of Aging

As the aging population expands, it will become increasingly important for health care providers to become aware of and sensitive to the needs and concerns of older adults.Ageismis a term that describes negative stereotyping of older adults and discrimination because of older age. Health concerns and symptoms in the elderly may be overlooked or dismissed as part of the normal aging process. Consequently, several conditions in olders adults are significantly underdiagnosed and undertreated. Misconceptions about aging frequently encountered in medicine and in society at large include issues involving sexuality, sleep disturbance, depression, cognitive impairment, and substance abuse. We can learn to recognize ageist notions that influence medical practice. Perhaps by becoming more aware of myths and realities of aging, we can improve the health and quality of life of our elderly patients.

Personality and incident disability in older persons

OBJECTIVE

to examine the relation of personality to the development of disability in old age.

METHODS

participants are 813 older Catholic nuns, priests and brothers without dementia or disability at study onset. As part of a uniform baseline evaluation, they completed standard measures of the five principal dimensions of personality. Disability was assessed at baseline and annually thereafter with the Katz scale. The relation of each trait to incident disability was assessed in proportional hazard models controlled for age, sex, education and selected clinical variables.

RESULTS

during a mean of about 6 years of observation, 255 persons (31%) became dependent on at least one activity of daily living. Risk of becoming disabled was 85% [95% confidence interval (CI) = 80.5-89.6%] lower in persons with high (90th percentile) compared to low (10th percentile) extraversion and 50% (95% CI = 46.6-54.2%) lower in those with high compared to low conscientiousness, and controlling for chronic medical conditions, depressive symptoms or social and cognitive activity did not substantially affect these associations. By contrast, neuroticism had a marginal association with disability risk that was eliminated after controlling for depressive symptomatology, and openness and agreeableness were unrelated to disability risk.

CONCLUSIONS

The results suggest that higher levels of extraversion and conscientiousness may be associated with a reduced risk of incident disability in old age.

Hippocampal disconnection contributes to memory dysfunction in individuals at risk for Alzheimer's disease

The concept of amnestic mild cognitive impairment (MCI) describes older people who show a decline predominantly in memory function, but who do not meet criteria for dementia. Because such individuals are at high risk for developing Alzheimer's disease, they are of great interest for understanding the prodromal stages of the disease process. The mechanism underlying memory dysfunction in people with MCI is not fully understood. The present study uses quantitative, high-resolution structural MRI techniques to investigate, in vivo, the anatomical substrate of memory dysfunction associated with MCI. Changes in brain structures were assessed with two imaging techniques: (i) whole-brain, voxel-based morphometry to determine regions of reduced white matter volume and (ii) sensitive volumetric segmentation of the entorhinal cortex and hippocampus, gray matter regions that are critically important for memory function. In participants with amnestic MCI, compared with age-matched controls, results showed a significant decrease in white matter volume in the region of the parahippocampal gyrus that includes the perforant path. There was also significant atrophy in both the entorhinal cortex and the hippocampus. Regression models demonstrated that both hippocampal volume and parahippocampal white matter volume were significant predictors of declarative memory performance. These results suggest that, in addition to hippocampal atrophy, disruption of parahippocampal white matter fibers contributes to memory decline in elderly individuals with MCI by partially disconnecting the hippocampus from incoming sensory information.

Myeloperoxidase polymorphism and cognitive decline in older adults in the Health, Aging, and Body Composition Study

Myeloperoxidase, an antimicrobial enzyme, produces oxidative free radicals. Rarely found in normal brain tissue, myeloperoxidase has been detected in microglia associated with Alzheimer's disease plaques. The authors examined a G-463A polymorphism in the promoter region of the myeloperoxidase gene (MPO) to determine the relation of MPO variants to cognitive decline over 4 years in a cohort of adults, aged 70-79 years at baseline (1997-1998), recruited from Memphis, Tennessee, and Pittsburgh, Pennsylvania, into the Health, Aging, and Body Composition Study. In this sample, 8% of the participants had the AA, 36.9% the AG, and 55.2% the GG genotype of MPO. The frequency of AA and AG genotypes was higher in Blacks than Whites (11.2% vs. 5.9%, and 44.1% vs. 32.9%, respectively). Multivariate logistic regression analyses showed that, for participants with the MPO AA genotype, cognitive decline was 1.58 (95% confidence interval: 1.07, 2.35) times more likely than for participants with the AG genotype and 1.96 (95% confidence interval: 1.33, 2.88) times more likely than for those with the GG genotype. Interactions between MPO and race, sex, or the apolipoprotein gene were not significant. In this sample, MPO AA, associated with decreased production of myeloperoxidase, was found to be a risk factor for cognitive decline.

The significance of thyroid-stimulating hormone and homocysteine in the development of Alzheimer's disease in mild cognitive impairment: a 6-year follow-up study

Mild cognitive impairment (MCI) represents a transition between normal aging and Alzheimer's disease (AD). The aim of this study was to investigate the predictive value of vitamin B12/folate, homocysteine, standard laboratory parameters, and concomitant diseases for development of AD in persons with an MCI diagnosis. Development of dementia was followed for 6 years in 93 consecutively recruited MCI persons. Information concerning the above factors was obtained from medical journals. Thirty-four percent of participants converted to AD within 6 years. A forward stepwise logistic regression was performed. The odds ratio (OR) for the Mini-Mental State Examination (MMSE) was 0.777; for age, 1.084; and for thyroid stimulating hormone (TSH), 0.287. The OR for homocysteine was 1.287 at 60 years of age and 1.087 at 65 years of age. Lower TSH levels together with the more established factors lower MMSE, higher homocysteine levels, and age were found to be predictive factors of AD. This may have clinical implications with regard to monitoring TSH levels and thyroxin substitution in MCI patients.

Neuropsychological markers of progression from mild cognitive impairment to Alzheimer's disease

To find early clinical markers that may predict a likely progression to Alzheimer's disease (AD), the authors performed neuropsychological tests on 82 mild cognitive impairment (MCI) subjects. After 3 years, 38 patients developed AD while 44 retained the diagnosis of MCI. The cognitive differences between the groups were studied. Patients who developed AD showed significantly lower values than did MCI subjects in some neuropsychological scores (P = .02-.001), with sensitivities and specificities higher than 84% and 64%, respectively, for detecting early-onset AD, with a 7.9-fold increased risk of converting to AD (P < .001). Regarding the logistic regression model, the CAMCOG Memory and Perception cognitive screening items were the optimum independent tools to classify the patients who will progress to AD, showing a relative risk of progression of 10.5 (P = .002), 5.5 (P = .008), and 3.9 times (P = .05), respectively, with a sensibility of of 92.1% and a specificity 72.7%.

Shift in the ratio of three-repeat tau and four-repeat tau mRNAs in individual cholinergic basal forebrain neurons in mild cognitive impairment and Alzheimer's disease

Molecular mechanisms underlying tauopathy remain undetermined. In the current study, single cell gene expression profiling was coupled with custom-designed cDNA array analysis to evaluate tau expression and other cytoskeletal elements within individual neuronal populations in patients with no cognitive impairment (NCI), mild cognitive impairment (MCI), and Alzheimer's disease (AD). Results revealed a shift in the ratio of three-repeat tau (3Rtau) to four-repeat tau (4Rtau) mRNAs within individual human cholinergic basal forebrain (CBF) neurons within nucleus basalis (NB) and CA1 hippocampal neurons during the progression of AD, but not during normal aging. A shift in 3Rtau to 4Rtau may precipitate a cascade of events in the selective vulnerability of neurons, ultimately leading to frank neurofibrillary tangle (NFT) formation in tauopathies including AD.

Substantia nigra tangles are related to gait impairment in older persons

OBJECTIVE

Parkinsonian signs, especially gait impairment, are common and associated with morbidity and mortality in older persons. Our objective was to test the hypothesis that substantia nigra neurofibrillary tangles (NFTs) are related to parkinsonian signs in older persons with and without dementia.

METHODS

We studied 86 deceased older Catholic clergy without idiopathic Parkinson's disease from the Religious Order Study, a longitudinal clinical-pathological study. Mean age at death was 85.3 years. Signs of gait disturbance, bradykinesia, rigidity, and tremor were assessed proximate to death using a modified Unified Parkinson's Disease Rating Scale. Forty-micrometer paraffin-embedded sections of substantia nigra were bleached before tau immunohistochemistry and the optical disector was used to count NFTs. We used multivariable linear regression to examine parkinsonian signs as a function of nigra NFTs, controlling for age, sex, education, and cortical NFTs.

RESULTS

Substantia nigra NFTs were present in 67 of 86 persons (77.9%). After controlling for age, sex, education, and cortical NFTs, nigra NFTs were related to gait impairment (p < 0.001), but not bradykinesia, rigidity, or tremor. Results were not confounded by dementia, Braak score, neuroleptic medication, cerebral infarcts, or Lewy bodies.

INTERPRETATION

NFTs in the substantia nigra are associated with gait impairment in older persons with and without dementia.

Down regulation of trk but not p75NTR gene expression in single cholinergic basal forebrain neurons mark the progression of Alzheimer's disease

Dysfunction of cholinergic basal forebrain (CBF) neurons of the nucleus basalis (NB) is a cardinal feature of Alzheimer's disease (AD) and correlates with cognitive decline. Survival of CBF neurons depends upon binding of nerve growth factor (NGF) with high-affinity (trkA) and low-affinity (p75(NTR)) neurotrophin receptors produced within CBF neurons. Since trkA and p75(NTR) protein levels are reduced within CBF neurons of people with mild cognitive impairment (MCI) and mild AD, trkA and/or p75(NTR) gene expression deficits may drive NB degeneration. Using single cell expression profiling methods coupled with custom-designed cDNA arrays and validation with real-time quantitative PCR (qPCR) and in situ hybridization, individual cholinergic NB neurons displayed a significant down regulation of trkA, trkB, and trkC expression during the progression of AD. An intermediate reduction was observed in MCI, with the greatest decrement in mild to moderate AD as compared to controls. Importantly, trk down regulation is associated with cognitive decline measured by the Global Cognitive Score (GCS) and the Mini-Mental State Examination (MMSE). In contrast, there is a lack of regulation of p75(NTR) expression. Thus, trk defects may be a molecular marker for the transition from no cognitive impairment (NCI) to MCI, and from MCI to frank AD.

Mild cognitive impairment (MCI) and actual retrieval performance affect cerebral activation in the elderly

Cerebral activation in the elderly may depend on general cognitive decline as well as actual retrieval performance. Consequently, activation between subjects with and without Mild Cognitive Impairment (MCI), and between remembered and non-remembered words was compared. Twenty-one MCI and 29 healthy control subjects learned 180 nouns. During retrieval, subjects had to discriminate these and 180 distractor words. fMRI identified response-related activation. Most retrieval-related activation was comparable in both groups. However, MCI subjects showed more activation in the prefrontal cortex than controls during processing of hits and correct rejections. Hits showed increased activation than misses in the precuneus and left lateral parieto-occipital cortex; misses showed more activation than correct rejections in the precuneus to cuneus. Verbal retrieval activated a large common network in the elderly independently of MCI. Increased activation in MCI subjects in prefrontal cortex depends on response category. Activation differences between response categories might reflect success (hits) and effort (misses). Increased retrieval-related activation may be used as early marker in subjects at risk of Alzheimer's disease.

Functional connectivity of the fusiform gyrus during a face-matching task in subjects with mild cognitive impairment

Cognitive function requires a high level of functional interaction between regions of a network supporting cognition. Assuming that brain activation changes denote an advanced state of disease progression, changes in functional connectivity may precede changes in brain activation. The objective of this study was to investigate changes in functional connectivity of the right middle fusiform gyrus (FG) in subjects with mild cognitive impairment (MCI) during performance of a face-matching task. The right middle FG is a key area for processing face stimuli. Brain activity was measured using functional MRI. There were 16 MCI subjects and 19 age-matched healthy controls. The linear correlation coefficient was utilized as a measure of functional connectivity between the right middle FG and all other voxels in the brain. There were no statistical differences found in task performance or activation between groups. The right middle FG of the healthy control and MCI groups showed strong bilateral positive linear correlation with the visual cortex, inferior and superior parietal lobules, dorsolateral prefrontal cortex (DLPFC) and anterior cingulate. The healthy controls showed higher positive linear correlation of the right middle FG to the visual cortex, parietal lobes and right DLPFC than the MCI group, whereas the latter had higher positive linear correlation in the left cuneus. In the healthy controls, the right middle FG had negative linear correlation with right medial frontal gyrus and superior temporal gyrus and with left inferior parietal lobule (IPL), angular gyrus, superior frontal gyrus and anterior cingulate gyrus, but the MCI group had negative linear correlation with the left IPL, angular gyrus, precuneus, anterior cingulate, and to right middle temporal gyrus and posterior cingulate gyrus. In the negatively linearly correlated regions, the MCI group had reduced functional connectivity to the frontal areas, right superior temporal gyrus and left IPL. Different regions of the cuneus and IPL had increased functional connectivity in either group. The putative presence of Alzheimer's disease neuropathology in MCI affects functional connectivity from the right middle FG to the visual areas and medial frontal areas. In addition, higher linear correlation in the MCI group in the parietal lobe may indicate the initial appearance of compensatory processes. The results demonstrate that functional connectivity can be an effective marker for the detection of changes in brain function in MCI subjects.

Increased Metabolic Activity in Nucleus Basalis of Meynert Neurons in Elderly Individuals With Mild Cognitive Impairment as Indicated by the Size of the Golgi Apparatus

In this study, we examined the metabolic activity of nucleus basalis of Meynert (NBM) neurons in individuals clinically diagnosed with no cognitive impairment (NCI, n = 8), mild cognitive impairment (MCI, n = 9), and subjects with moderate Alzheimer disease (AD, n = 7). We used Golgi apparatus (GA) size as a measure of neuronal metabolic activity. Subjects with MCI showed increased NBM metabolic activity; they had significantly more neurons with larger GA size as compared with NCI and AD subjects. In contrast, more NBM neurons with extremely small GA sizes, indicating reduced metabolic activity, were seen in AD. When these cases were classified according to their AD pathology (Braak I-II, III-IV, or V-VI), Braak III-IV subjects showed significantly increased GA sizes, comparable with the increase in clinically diagnosed MCI, whereas in Braak V-VI, GA sizes were dramatically reduced. Of all MCI and NCI subjects with similar Braak III-IV pathology, the MCI subjects again had significantly larger GA sizes. The larger NBM neuronal GA size seen in MCI suggests increased metabolic activity, associated with both the clinical progression from NCI to MCI, and with the early stages of AD pathology.

High-Sensitivity C-Reactive Protein and Cognitive Function in Older Women

BACKGROUND

Inflammatory processes may be involved in the development of dementia, although findings from epidemiologic studies directly examining inflammatory markers and dementia or its precursor, impaired cognitive function, are inconsistent.

METHODS

We measured plasma levels of the inflammatory marker, C-reactive protein, using a high-sensitivity assay (hs-CRP) in 4,231 older participants of the Women's Health Study, who provided blood samples between 1992 and 1996 when they were age 60 to 90 years. From 1998 to 2000, we administered a battery of 5 cognitive tests measuring general cognition, verbal memory, and category fluency. Using multiple linear regression, we compared mean cognitive test scores across quintiles of hs-CRP, adjusting for potential confounding factors.

RESULTS

There was a wide distribution of hs-CRP levels among these women, and a large proportion had levels considered to reflect a high risk of cardiovascular disease. We observed no suggestion, however, that higher hs-CRP levels were associated with poorer cognitive performance. For example, on a global score combining results of all the cognitive tests, mean scores among women in the highest quintile of hs-CRP did not differ from those in the lowest quintile (multivariable-adjusted mean difference = 0.04; 95% confidence interval [CI]: -0.02 to 0.11, P for trend across quintiles = 0.38).

CONCLUSION

Overall, in these women, we found no evidence of a link between hs-CRP, a marker of inflammation, and decrements in cognitive function.

The relation of cigarette smoking to incident Alzheimer's disease in a biracial urban community population

The relationship between smoking status and incident Alzheimer's disease (AD) was investigated in a random stratified sample of a biracial community in Chicago. Analyses are based on 1,064 persons (of 1,134 evaluated) who had data on smoking status, disease incidence, and key covariates such as apolipoprotein allele status. During a mean of about 4 years of follow-up, 170 persons met criteria for incident AD. Current smoking was associated with increased risk of incident AD (OR = 3.4, 95% CI = 1.4-8.0) compared to persons who never smoked. There was no apparent increase in risk of AD for former smokers compared to persons who never smoked (OR = 0.9, 95% CI = 0.5-1.7). Apolipoprotein E allele status modified this association in that former smokers with a upsilon4 allele were less likely to develop AD (p = 0.04) than those who never smoked. Former smokers also appeared to have a reduced risk of developing AD as their pack-years of smoking increased (p = 0.02)such that the odds of developing AD increased by 50% for every 10 years of smoking cessation (OR = 1.3, CI = 0.9-1.7). The results suggest that older people who currently smoke are more likely to develop AD compared to those who never smoked; the relation between those who used to smoke but quit and the risk of AD is complex and requires further research.