Neuropsychiatric Symptom Profile in Alzheimer's Disease and Their Relationship With Functional Decline.

OBJECTIVE: Understanding the course of individual neuropsychiatric symptoms (NPS) and their relationship with function is important for planning targeted interventions for preventing and delaying functional decline. This study aims to disentangle relative contributions of individual NPS on functional decline. METHODS: Longitudinal study of 9,358 well-characterized participants with baseline diagnoses of Mild Cognitive Impairment or AD in the National Alzheimer's Coordinating Center Uniform Data Set. Function was measured using the Functional Assessment Questionnaire (FAQ). Clinician judgment of seven common behavioral symptoms were examined simultaneously: apathy-withdrawal, depressed mood, visual or auditory hallucinations, delusions, disinhibition, irritability, and agitation. RESULTS: Apathy was the most common NPS at baseline (33.7%) and throughout follow-up, endorsed by clinicians in 63.7% of visits. Apathy was the most persistent with 36.7% of participants having clinician-endorsed apathy in ≥50% of their visits. Apathy strongly correlated with faster rate of functional decline. Compared to those who never had apathy, baseline FAQ was worse in those with intermittent or persistent/always apathy (intermittent: estimated coefficient ±SE=1.228±0.210, 95% CI=[0.817, 1.639]; persistent/always: 2.354±0.244 (95% CI=[1.876, 2.832], both p <0.001). Over time, rate of functional decline was faster in those with intermittent and persistent/always apathy (intermittent: 0.454±0.091, 95% CI=[0.276, 0.632]; persistent/always: 0.635±0.102, 95% CI=[0.436, 0.835], both p <0.001). Worse agitation, delusions, and hallucinations also correlated with functional decline, but magnitudes of the estimates were smaller. CONCLUSION: Individual NPS may be sensitive targets for tracking longitudinal change in function. The study raises awareness of the need for more comprehensive assessment of functional decline in AD patients with noncognitive symptoms.

Apathy in Lewy body disease and its effects on functional impairment over time.

Background and objectives: Apathy strongly affects function in Alzheimer's disease and frontotemporal dementia, however its effect on function in Lewy Body Disease (LBD) has not been well-described. This study aims to (1) examine the prevalence and persistence of apathy in a large, national cohort of well-characterized patients with LBD, and (2) estimate the effect of apathy on function over time. Methods: Study included 676 participants with mild cognitive impairment (MCI) or dementia in the National Alzheimer's Coordinating Center Uniform Data Set. Participants were followed for an average of 3.4 ± 1.7 years and consistently had a primary diagnosis of LBD. Apathy was defined by clinician judgment, categorized into four mutually exclusive profiles: (1) never apathetic across all visits, (2) at least one but <50% of visits with apathy (intermittent apathy), (3) ≥50% but not all visits with apathy (persistent apathy), and (4) always apathy across all visits. Dementia severity was measured by baseline Clinical Dementia Rating score. Parkinsonism was defined by the presence of bradykinesia, resting tremor, rigidity, gait, and postural instability. Functional impairment was assessed using the Functional Assessment Questionnaire (FAQ). Results: Baseline characteristics of the sample were: average age = 72.9 ± 6.9, years of education = 15.6 ± 3.4, Mini Mental State Exam (MMSE) = 24.4 ± 5.4, Geriatric Depression Scale (GDS) = 3.8 ± 3.2, FAQ = 12.0 ± 9.1. 78.8% were male and 89% were non-Hispanic white. Prevalence of apathy increased from 54.4% at baseline to 65.5% in year 4. 77% of participants had apathy at some point during follow-up. Independent of cognitive status and parkinsonian features, FAQ was significantly higher in participants with intermittent/persistent and always apathetic than never apathetic. Annual rate of decline in FAQ was faster in participants who were always apathetic than never apathy. Discussion: In this large national longitudinal cohort of LBD patients with cognitive impairment, apathy was strongly associated with greater functional impairment at baseline and faster rate of decline over time. The magnitude of these effects were clinically important and were observed beyond the effects on function from participants' cognitive status and parkinsonism, highlighting the importance of specifically assessing for apathy in LBD.

Apathy and Functional Impairment in the Course of Behavioral Variant Frontotemporal Dementia.

This cohort study analyzes patterns of apathy and functional impairment in patients with progressive severity of behavioral variant frontotemporal dementia.

Agitation in Cognitive Disorders: Use of the National Alzheimer's Coordinating Center Uniform Data Set (NACC-UDS) to Evaluate International Psychogeriatric Association Definition.

OBJECTIVE: Consensus-based definition of agitation by the International Psychogeriatric Association (IPA) has not been evaluated in community-based samples who are not preselected for behavioral disturbances. Here, we use a well-characterized cohort of community-dwelling older adults with cognitive impairment to assess the IPA criteria associated with agitation to evaluate the construction of this diagnostic entity. METHODS: We used the National Alzheimer Coordinating Center Unified Data Set (NACC-UDS) to construct the IPA consensus-based provisional definition of agitation in cognitive impairment (N = 19,424). We used clinician diagnosis of agitation as a gold standard in those with mild cognitive impairment and dementia and used the Neuropsychiatric Inventory-Questionnaire to define agitation symptoms and standardized assessments of function (including the Functional Assessment Scale and Clinical Dementia Rating Scale Sum of Boxes) to assess "excess disability." We also examined patterns of psychiatric comorbidities to determine if they were consistent with IPA criteria. RESULTS: There was agreement between the selected NPI measure of agitation and clinician judgment (sensitivity = 0.79, specificity = 0.69, Cohen's Kappa = 0.304). More than 84% of those with clinician judgment of agitation and 74% of those meeting the scale-based definition of agitation demonstrated excess social/functional disability. Comorbid psychiatric symptoms were present in 38% of the sample without agitation and higher in those with agitation by either definition. CONCLUSION: Agitation ranges between 15% and 48% in those with cognitive impairment. The pattern of level of excess disability and the presence of comorbid psychiatric symptoms is consistent with the profile of published definitions.

Prevalent, persistent, and impairing: Longitudinal course and impact of apathy in Alzheimer's disease.

INTRODUCTION: Understanding of the natural history of apathy and its impact on patient function is limited. This study examines, in a large, national sample of Alzheimer's disease (AD) patients with long follow-ups: (1) prevalence, incidence, and persistence of apathy, and (2) impact of apathy on function across dementia severity. METHODS: A longitudinal study of 9823 well-characterized AD patients in the National Alzheimer's Coordinating Center Uniform Data Set. RESULTS: Apathy was highly prevalent across disease severity with cumulative prevalence of 48%, 74%, and 82% in Clinical Dementia Rating (CDR) 0.5, 1.0, and 2.0, respectively. Persistence of apathy from clinician judgment varied from visit to visit at earlier disease stages but remained high at moderate dementia. Independent of cognition, persistent apathy was strongly associated with accelerated rate of functional decline. DISCUSSION: Findings point to important targets for the treatment and management of apathy, include functional outcomes, and study designs that account for variable persistence of the apathy syndrome.

Why Do They Just Sit? Apathy as a Core Symptom of Alzheimer Disease.

OBJECTIVE: Apathy is common in Alzheimer disease (AD) and has a far-reaching impact on patients' clinical course and management needs. However, it is unclear if apathy is an integral component of AD or a manifestation of depression in cognitive decline. This study aims to examine interrelationships between apathy, depression, and function. METHODS: This was a cross-sectional study of well-characterized AD patients in the National Alzheimer's Coordinating Center Uniform Data Set with a Clinical Dementia Rating (CDR) between 0.5 and 2. Participants' function was measured using the Functional Assessment Questionnaire. Apathy and depression were measured using clinician judgment and informant-reported Neuropsychiatric Inventory-Questionnaire. Dementia severity was categorized by CDR. RESULTS: Sample included 7,679 participants (55.7% men) with a mean (standard deviation) age of 74.9 (9.7) years; 3,197 (41.6%) had apathy based on clinician judgment. Among those with apathy, approximately half had no depression. Presence of apathy was associated with 21%, 10%, and 3% worsening in function compared with those without apathy in CDR 0.5, 1, and 2 groups, respectively. Depression was not independently associated with functional status. Results revealed no interaction between apathy and depression. CONCLUSION: Apathy, but not depression, was significantly associated with worse function, with the strongest effects in mild dementia. Results emphasize the need for separate assessments of apathy and depression in the evaluation and treatment of patients with dementia. Understanding their independent effects on function will help identify patients who may benefit from more targeted management strategies.

Functional neural correlates of attentional deficits in amnestic mild cognitive impairment.

Although amnestic mild cognitive impairment (aMCI; often considered a prodromal phase of Alzheimer's disease, AD) is most recognized by its implications for decline in memory function, research suggests that deficits in attention are present early in aMCI and may be predictive of progression to AD. The present study used functional magnetic resonance imaging to examine differences in the brain during the attention network test between 8 individuals with aMCI and 8 neurologically healthy, demographically matched controls. While there were no significant behavioral differences between groups for the alerting and orienting functions, patients with aMCI showed more activity in neural regions typically associated with the networks subserving these functions (e.g., temporoparietal junction and posterior parietal regions, respectively). More importantly, there were both behavioral (i.e., greater conflict effect) and corresponding neural deficits in executive control (e.g., less activation in the prefrontal and anterior cingulate cortices). Although based on a small number of patients, our findings suggest that deficits of attention, especially the executive control of attention, may significantly contribute to the behavioral and cognitive deficits of aMCI.

C-reactive protein and familial risk for dementia: a phenotype for successful cognitive aging.

OBJECTIVES: Identifying phenotypes for successful cognitive aging, intact cognition into late-old age (>age 75), can help identify genes and neurobiological systems that may lead to interventions against and prevention of late-life cognitive impairment. The association of C-reactive protein (CRP) with cognitive impairment and dementia, observed primarily in young-elderly samples, appears diminished or reversed in late-old age (75+ years). A family history study determined if high CRP levels in late-old aged cognitively intact probands are associated with a reduced risk of dementia in their first-degree family members, suggesting a familial successful cognitive aging phenotype. METHODS: The primary sample was 1,329 parents and siblings of 277 cognitively intact male veteran probands at least 75 years old. The replication sample was 202 relatives of 51 cognitively intact community-ascertained probands at least 85 years old. Relatives were assessed for dementia by proband informant interview. Their hazard ratio (HR) for dementia as a function of the proband's log-transformed CRP was calculated using the proportional hazards model. RESULTS: Covarying for key demographics, higher CRP in probands was strongly associated with lower risk of dementia in relatives (HR = 0.55 [95% confidence interval (CI) 0.41, 0.74], p < 0.02). The replication sample relationship was in the same direction, stronger in magnitude, and also significant (HR = 0.15 [95% CI 0.06, 0.37], p < 0.0001). CONCLUSIONS: Relatives of successful cognitive aging individuals with high levels of CRP are relatively likely to remain free of dementia. High CRP in successful cognitive aging individuals may constitute a phenotype for familial-and thus possibly genetic-successful cognitive aging.

Changes in glycemic control are associated with changes in cognition in non-diabetic elderly.

The aim of the present study was to examine the relationship of changes in long term glucose levels as measured by Hemoglobin A1c (HbA1c) with simultaneous changes in cognition. The sample included in the present analysis consisted of 101 community dwelling non-diabetic elderly subjects participating in ongoing longitudinal studies of cognition. Subjects were included in this study if they were cognitively normal at baseline, had at least one co-temporaneous follow-up assessment of HbA1c and the Mini Mental State Exam (MMSE), and complete data on age, gender, race, and years of education. MMSE decline over time was the main outcome measure. In TOBIT mixed regression models, MMSE was the dependent variable and HbA1c the time-varying covariate. Sociodemographic (age, gender, and education), cardiovascular (hypertension and APOE4 status), and lifestyle (smoking and physical activity) covariates were included in the statistical model. After adjusting for age at follow-up, there was a decrease of 1.37 points in the MMSE (p = 0.0002) per unit increase in HbA1c. This result remained essentially unchanged after adjusting also for gender and education (p = 0.0005), cardiovascular factors (p = 0.0003), and lifestyle (p = 0.0006). Additionally, results remained very similar after excluding subjects with potentially incipient diabetes with HbA1c between 6 and 7. These findings suggest that in non-diabetic non-demented elderly subjects, an increase in HbA1c over time is associated with cognitive decline. Such results may have broad clinical applicability since manipulation of glucose control, even in non-diabetics, may affect cognitive performance, perhaps enabling preventive measures against dementia.

Cognition in non-demented diabetic older adults.

Evidence links diabetes mellitus to cognitive impairment and increased risk of Alzheimer's disease (AD) and suggests that insulin therapy improves cognition. With an increasing percentage of the US elderly population at high risk for diabetes and AD, the evidence of an association between diabetes and poor cognition in non-demented elderly may have implications for diagnosis, prevention and treatment of cognitive decline including AD. In our study, we hypothesized that diabetic elders with normal cognition would demonstrate poorer cognitive outcomes than non-diabetic elders and that diabetic elders receiving diabetes treatment would demonstrate better outcomes than those not receiving treatment. Data were evaluated from the National Alzheimer's Coordinating Center's Uniform Data Set (UDS). The UDS consists of clinical and neuropsychological assessments of a sample of elderly research subjects recruited from thirty-one Alzheimer's Disease Centers nationwide. The UDS provides a unique opportunity to study cognition in a nationally recruited sample with structured neuropsychological tests. We examined the impact of diabetes and diabetes treatment on cognitive measures in 3421 elderly research subjects from 2005-2007 with normal cognition. We performed linear regression analyses to compare cognitive scores between diabetic subjects and non-diabetic subjects. Diabetic subjects had lower scores than non-diabetic subjects including attention, psychomotor function and executive function, but no differences in memory or semantic memory language. There was no association between diabetes treatment and cognitive scores. These subtle but significant cognitive deficits in diabetic subjects compared to non-diabetic subjects may contribute to difficulty with compliance with complex diabetes medication regimens. A specific role of diabetes as a risk for cognitive impairment will require longitudinal study.

Serum concentration of an inflammatory glycotoxin, methylglyoxal, is associated with increased cognitive decline in elderly individuals.

BACKGROUND: Advanced glycations end products increase oxidant stress, inflammation, and neurotoxicity. Serum levels are increased in diabetes and aging. We examined the relationship between serum methylglyoxal derivatives (sMG), and cognitive decline, in 267 non-demented elderly. METHODS: Tobit mixed regression models assessed the association of baseline sMG with cognitive decline in the Mini Mental State Exam (MMSE) over time, controlling for sociodemographic factors (age, sex, and years of education), cardiovascular risk factors (diabetes and presence of an ApoE4 allele), and kidney function. sMG was assessed by ELISA. RESULTS: The fully adjusted model showed an annual decline of 0.26 MMSE points per unit increase in baseline sMG (p = 0.03). Significance was unchanged as additional risk factors were added to the model. The interactions of sMG with diabetes, sex, age, kidney function, and ApoE4 genotype were not significant. CONCLUSIONS: Higher levels of baseline sMG were associated with a faster rate of cognitive decline, after adjusting for several sociodemographic and clinical characteristics. This relationship did not differ by sex, ApoE4 genotype, or diabetes status suggesting its generality. Since subjects were cognitively normal at the beginning of the study, elevated sMG may be indicative of brain cell injury initiated before clinically evident cognitive compromise.

The association of age with rate of cognitive decline in elderly individuals residing in supporting care facilities.

OBJECTIVES: This study examines the effect of age on rate of cognitive decline in different stages of dementia, of nursing home and assisted-living residents. METHODS: In this longitudinal study, the Mini Mental State Examination (MMSE) was used to measure rate of cognitive decline in subjects who were nondemented [Clinical Dementia Rating (CDR)=0; n=353], questionably demented (CDR=0.5; n=121), or frankly demented (CDR≥1; n=213) at baseline. RESULTS: A generalized estimating equation was used to model the MMSE scores over time (mean follow-up 2.9±2.0 y). The generalized estimating equation model had the MMSE scores at successive follow-up time points as dependent variables and had linear and quadratic age, follow-up time from baseline, CDR at baseline, and all the interactions among them as independent variables, controlling for MMSE at baseline, sex, race, and education. The mean age of the entire sample was 85.2±7.4 years at baseline. There were no significant interactions of linear age effects with rate of cognitive decline. The analysis of interaction of quadratic age with rate of cognitive decline showed complex relationships: in the nondemented group, there was no substantial quadratic association of age with the rate of cognitive decline (P=0.13); in the questionable demented group, the oldest subjects declined relatively faster (P=0.02); and in the demented group, the youngest and oldest subjects tended to decline relatively less than subjects in the intermediate ages (P=0.07). CONCLUSIONS: This study adds an additional aspect to the complexity of the association between age and rate of cognitive decline, showing that the direction and amplitude of this effect differs according to the stage along the course of cognitive decline.

Cognitive decline in patients with dementia as a function of depression.

OBJECTIVE: There is evidence that major depression increases the risk for dementia, but there is conflicting evidence as to whether depression may accelerate cognitive decline in dementia. The authors tested the hypothesis that decline in cognitive function over time is more pronounced in patients with dementia with comorbid depression, when compared with patients with dementia without depression history. DESIGN: Prospective, longitudinal cohort study of aging. SETTING: Nursing home. PARTICIPANTS: Three hundred thirteen elderly nursing home residents (mean age at baseline: 86.99 years, standard deviation = 6.7; 83.1% women). At baseline, 192 residents were diagnosed with dementia, and another 27 developed dementia during follow-up. Thirty residents suffered from major depression at any point during the study, and 48 residents had a history of depression. MEASUREMENTS: The authors measured cognitive decline using change in Mini-Mental State Examination (MMSE) scores over up to 36 months. The authors calculated multilevel regression models to estimate the effects of age, gender, education, dementia status, depression, depression history, and an interaction between dementia and depression, on change in MMSE scores over time. RESULTS: Beyond the effects of age, gender, and education, residents showed steeper cognitive decline in the presence of dementia (ß = -13.69, standard error = 1.38) and depression (ß = -4.16, SE = 1.2), which was further accelerated by the presence of both depression and dementia (ß = -2.72, SE = 0.65). CONCLUSIONS: In dementia, the presence of depression corresponds to accelerated cognitive decline beyond gender and level of education, suggesting a unique influence of depression on the rate of cognitive decline in dementia.

The MMSE orientation for time domain is a strong predictor of subsequent cognitive decline in the elderly.

BACKGROUND: The mini-mental state exam (MMSE) has been used to address questions such as determination of appropriate cutoff scores for differentiation of individuals with intact cognitive function from patients with dementia and rate of cognitive decline. However, little is known about the relationship of performance in specific cognitive domains to subsequent overall decline. OBJECTIVE: To examine the specific and/or combined contribution of four MMSE domains (orientation for time, orientation for place, delayed recall, and attention) to prediction of overall cognitive decline on the MMSE. METHODS: Linear mixed models were applied to 505 elderly nursing home residents (mean age = 85, > 12 years education = 27%; 79% F, mean follow-up = 3.20 years) to examine the relationship between baseline scores of these domains and total MMSE scores over time. RESULTS: Orientation for time was the only domain significantly associated with MMSE decline over time. Combination of poor delayed recall with either attention or orientation for place was associated with significantly increased decline on the MMSE. CONCLUSIONS: The MMSE orientation for time predicts overall decline on MMSE scores over time. A good functioning domain added to good functioning delayed recall was associated with slower rate of decline.

Number of children is associated with neuropathology of Alzheimer's disease in women.

OBJECTIVE: To examine the association between number of born children and neuropathology of Alzheimer's disease (AD). METHODS: The brains of 86 subjects with data on the number of biological children born, were studied postmortem. Primary analyses included 73 subjects (average age at death=80; 42 women) devoid of cerebrovascular disease associated lesions (i.e., infarcts) or of non-AD related neuropathology. Women were significantly older at death than men (85.6 vs. 73.4; p<.0005) but did not differ significantly from men in number of children or dementia severity. Secondary analyses included 13 additional subjects who had concomitant cerebrovascular disease. Density of neuritic plaques (NPs) and neurofibrillary tangles (NFTs) in the hippocampus, entorhinal cortex, amygdala and multiple regions of the cerebral cortex, as well as composites of these indices reflecting overall neuropathology, were analyzed. For men and women separately, partial correlations, controlling for age at death and dementia severity, were used to assess the associations of number of children with these neuropathological variables. RESULTS: Among women, all the partial correlations were positive, with statistical significance for overall neuropathology (r=.37; p=.02), overall NPs (r=.36; p=.02), and for NPs in the amygdala (r=.47; p=.002). Among men, none of the partial correlations were statistically significant. Results of the secondary analyses were similar. CONCLUSIONS: Since the associations between number of children and neuropathology of AD were found for women only, they might reflect sex-specific mechanisms (such as variations in estrogen or luteinizing hormone levels) rather than social, economic, biological or other mechanisms common to both men and women.

Better memory functioning associated with higher total and low-density lipoprotein cholesterol levels in very elderly subjects without the apolipoprotein e4 allele.

OBJECTIVE: To examine the association of cholesterol with cognitive functioning in oldest old community dwelling individuals with and without the apolipoprotein e4 (APOE4) allele. METHOD: One hundred eighty-five nondemented, community dwelling individuals (>or=85) were assessed with a broad neuropsychological battery. Bloods were drawn to assess total, low-density lipoprotein (LDL), and high-density lipoprotein cholesterol, as well as for APOE genotyping. RESULTS: In contrast to our expectations, high total cholesterol and high LDL cholesterol were associated with higher memory scores for noncarriers of the APOE4 allele. No significant associations between cognitive performance and lipid profile were found for carriers of the APOE4 allele. CONCLUSIONS: In oldest old nondemented noncarriers of the APOE4 allele, high cholesterol is associated with better memory function. Further examination of the role of APOE genotype on the association between cholesterol and cognitive performance, especially in the oldest old is warranted.

Role of the neuropathology of Alzheimer disease in dementia in the oldest-old.

BACKGROUND: Neuritic plaques (NPs) and neurofibrillary tangles (NFTs) in the brain, especially in the hippocampus, entorhinal cortex, and isocortex, are hallmark lesions of Alzheimer disease and dementia in the elderly. However, this association has not been extensively studied in the rapidly growing population of the very old. OBJECTIVE: To assess the relationship between estimates of cognitive function and NP and NFT pathologic conditions in 317 autopsied persons aged 60 to 107 years. DESIGN: We studied the relationship between severity of dementia and the density of these characteristic lesions of Alzheimer disease in young-old, middle-old, and oldest-old persons. The relationship of the severity of dementia as measured by the Clinical Dementia Rating scale to the density of NPs and NFTs was then assessed in each age group. PARTICIPANTS: Three hundred seventeen brains of persons aged 60 years and older were selected to have either no remarkable neuropathological lesions or only NP and NFT lesions. Brains with any other neuropathological conditions, either alone or in addition to Alzheimer disease findings, were excluded. The study cohort was then stratified into the youngest quartile (aged 60-80 years), middle 2 quartiles (aged 81-89 years), and oldest quartile (aged 90-107 years). RESULTS: While the density of NPs and NFTs rose significantly by more than 10-fold as a function of the severity of dementia in the youngest-old group, significant increases in the densities of NPs and NFTs were absent in the brains of the oldest-old. This lack of difference in the densities of NPs and NFTs was due to reduced lesion densities in the brains of oldest-old persons with dementia rather than to increased density of these lesions in the brains of nondemented oldest-old persons. CONCLUSIONS: These findings suggest that the neuropathological features of dementia in the oldest-old are not the same as those of cognitively impaired younger-old persons and compel a vigorous search for neuropathological indices of dementia in this most rapidly growing segment of the elderly population.

Increased longevity in offspring of mothers with Alzheimer's disease.

Life expectancy is a familial trait. However, the effectiveness of using the age at death of a deceased parent to estimate life expectancy in their offspring can vary depending on whether death in the parent was due to extrinsic versus intrinsic causes, as well as demographic characteristics such as sex. While Alzheimer's disease (AD) risk increases with increased age, mortality for individuals with AD is increased in contrast to comparably aged individuals without AD. Yet in most cases it is not the defining neuropathology of AD that directly terminates life but instead conditions and illnesses extrinsic to AD pathology that nevertheless have increased likelihood in its presence. For this reason, we hypothesized that offspring of AD mothers would have greater longevity than offspring of mothers without AD (insufficient numbers prevented a comparable analysis using fathers with AD). The longevity of 345 offspring of 100 deceased 60+ year old AD mothers was compared with 5,465 offspring in 1,312 deceased 60+ year old non-AD mothers. We used a proportional hazards model that accounted for clustered (nonindependent) observations due to the inclusion of several offspring from the same family. In both an unadjusted model and one that adjusted for the age at death in the mother, and the sex and birth year in the offspring we found evidence for increased longevity in the offspring of AD mothers. The results suggest that, in addition to genes that might directly affect pathways leading to AD, there may be familial/genetic factors not connected to specific pathophysiological processes in AD but instead associated with increased longevity that contribute to the familial aggregation observed in AD.