Background/aims

Alzheimer's disease (AD) clinical trials enroll two participants: a patient and a study partner. The primary caregiver most often fills the role of study partner and most trial study partners are spousal caregivers.

Methods

AD trial inclusion criteria were applied to baseline data from 5,674 probable AD dementia research participants in the National Alzheimer's Coordinating Center Uniform Data Set. Eligibility was compared among patients with spousal, adult child, and other types of study partners.

Results

Patients with spousal study partners were more frequently eligible than patients with adult child study partners. Compared to patients with spousal study partners, patients with adult child study partners were more frequently ineligible because of age, residence in skilled nursing facility, low scores on the Mini-Mental State Examination, highscores on the Hachinski Ischemia Scale, and failure to fulfill a minimum number of weekly visits with the study partner.

Conclusions

In this sample, patients with adult child study partners were less likely to qualify for AD clinical trials than were patients with spousal study partners. This may contribute to the lower representation of patients with adult child caregivers in these studies.

To assist investigators in making design choices, we modeled Alzheimer's disease prevention clinical trials. We used longitudinal Clinical Dementia Rating Scale Sum of Boxes data, retention rates, and the proportions of trial-eligible cognitively normal participants age 65 and older in the National Alzheimer's Coordinating Center Uniform Data Set to model trial sample sizes, the numbers needed to enroll to account for drop out, and the numbers needed to screen to successfully complete enrollment. We examined how enrichment strategies affected each component of the model. Relative to trials enrolling 65-year-old individuals, trials enriching for older (minimum 70 or 75) age required reduced sample sizes, numbers needed to enroll, and numbers needed to screen. Enriching for subjective memory complaints reduced sample sizes and numbers needed to enroll more than age enrichment, but increased the number needed to screen. We conclude that Alzheimer's disease prevention trials can enroll elderly participants with minimal effect on trial retention and that enriching for older individuals with memory complaints might afford efficient trial designs.

Background

Apolipoprotein (APOE) e4 allele status has been linked to clinical presentation and progression in Alzheimer's disease; however, evidence for a role of APOE e4 in Parkinson's disease (PD) remains largely inconclusive. In this analysis we explored potential significant associations between APOE e4 allele status and characteristics of clinical presentation in patients with PD.

Methods

Data came from 424 subjects evaluated using the Uniform Data Set (UDS) assessment collected by the National Alzheimer's Coordinating Center. Subjects had a known year of diagnosis of PD and experienced change in motor function prior to any change in cognition. Linear and logistic regression were used to model the association between APOE e4 carrier status and clinical characteristics including measures of cognitive decline and motor and neuropsychiatric symptoms. Amyloid burden was also evaluated for a subset of patients who died and consented to autopsy.

Results

Odds of dementia were higher in APOE e4 carriers (OR = 5.15), and, on average, APOE e4 carriers scored two points worse on tests of episodic memory and the Clinical Dementia Rating Sum of Boxes assessment. There was little evidence to support an association between e4 carrier status and severity of motor features, and, of the four neuropsychiatric symptoms evaluated, only presence of hallucinations was significantly associated with APOE e4 carrier status (OR = 5.29). Neuropathology data revealed higher frequencies of neuritic and diffuse amyloid plaques in APOE e4 carriers compared to non-carriers.

Conclusions

APOE e4 allele status is associated with dementia and severity of Alzheimer's disease pathologic features in PD.

Introduction

No known studies have compared longitudinal characteristics between individuals with incident mild cognitive impairment due to Parkinson's disease (PD-MCI) versus Alzheimer's Disease (AD-MCI).

Methods

We used longitudinal data from the National Alzheimer's Coordinating Center's Uniform Data Set to compare 41 PD-MCI and 191 AD-MCI participants according to their demographics, presence of ≥1 APOE e4 allele, and baseline and change over time in clinical characteristics, neuropsychological test scores, and Clinical Dementia Rating sum of boxes (CDR-SB). Multivariable linear regression models with generalized estimating equations were used to account for clustered data and to test for baseline and longitudinal differences in neuropsychological test scores.

Results

PD-MCI and AD-MCI participants differed by many demographic and clinical characteristics. Significantly fewer PD-MCI participants developed dementia over one year. Compared to AD-MCI participants, PD-MCI participants performed better at baseline and over time on a global measure of cognition (Mini Mental State Exam), memory measures (immediate and delayed Logical Memory), and a language measure (Boston Naming Test), and additionally performed better over time on an attention measure (Digit Span Forward), a language measure (Vegetable List), a processing speed measure (Digit Symbol), and an overall measure of memory and functional impairment (CDR-SB).

Conclusion

Our study provides further evidence that PD-MCI is clinically distinct from AD-MCI and requires different tools for diagnosis and monitoring clinical progression. More importantly, this study suggests that PD-MCI takes longer to convert into dementia than AD-MCI, findings that require replication by other studies.

In 2012, florbetapir (F) (Amyvid) received US Food and Drug Administration approval as a diagnostic agent for detecting neuritic (β-amyloid) plaques in living patients. Although such approval is specifically not extended to the use of florbetapir as a single definitive diagnostic test for Alzheimer disease dementia (ADD), it is of considerable importance to examine its potential in this regard. To estimate the ability of florbetapir amyloid imaging to detect specified densities of postmortem-identified neuritic plaques, we used the data of Clark et al [Clark CM, Pontecorvo MJ, Beach TG, et al. Cerebral PET with florbetapir compared with neuropathology at autopsy for detection of neuritic amyloid-beta plaques: A prospective cohort study. Lancet Neurol 2012;11:669-78]. We then used the data of Beach et al [Beach TG, Monsell SE, Phillips LE, et al. Accuracy of the clinical diagnosis of Alzheimer disease at National Institute on Aging Alzheimer Disease Centers, 2005-2010. J Neuropathol Exp Neurol 2012;71:266-73], derived from the National Alzheimer's Coordinating Center, to estimate the fraction of subjects who would have been called florbetapir-positive and, among these, the fraction of subjects who would also meet neuropathologic criteria for the presence of ADD. The accuracy of a positive florbetapir β-amyloid scan for the detection of neuropathologically defined ADD is estimated at between 69% and 95% sensitivity and between 83% and 89% specificity. From the same National Alzheimer's Coordinating Center data set, 144 subjects were recorded as having normal cognition. Among these, 84 (58%) had at least sparse neuritic plaques at autopsy and, among these, florbetapir imaging was estimated to detect 47 (56%). These findings suggest that amyloid imaging may significantly improve the clinical identification of ADD.

Importance

Although cerebral amyloid angiopathy (CAA) has important clinical implications, our understanding of it and ability to diagnose it are limited.

Objective

To determine pathological correlates and clinical factors identifiable during life that predict the presence of severe CAA in persons with pathologically confirmed Alzheimer disease (AD).

Design, setting, and participants

We compared demographic and clinical variables at the earliest visit during life at which participants were found to have cognitive impairment and compared pathological variables between persons ultimately found to have no or severe CAA at autopsy using logistic regression. Analyses were repeated separately for carriers and noncarriers of the APOE ε4 allele. Data were obtained from the Uniform Data Set, which comprises longitudinal clinical assessments performed in the Alzheimer's Disease Centers funded by the National Institute on Aging. Participants included 193 persons with AD and severe CAA and 232 persons with AD and no CAA. All participants had cognitive impairment and met National Institute on Aging-Reagan Institute neuropathological criteria for AD.

Main outcomes and measures

Prevalence of demographic characteristics and the APOE ε4 allele and odds ratios (ORs) of clinical variables for the prediction of severe CAA.

Results

Persons with severe CAA compared with those without CAA were more likely to carry an APOE ε4 allele (64.9% vs 42.8%, respectively; P < .001), to be Hispanic (6.8% vs 1.3%, respectively; P = .003), to have had a transient ischemic attack (12.5% vs 6.1%, respectively; OR = 2.1; 95% CI, 1.0-4.4), and to have lower degrees of diffuse amyloid plaque pathology (mean [SD] Consortium to Establish a Registry for Alzheimer's Disease score, 1.2 [0.5] vs 1.4 [0.8], respectively; P = .01). Those with CAA compared with those without CAA more commonly had intracerebral hemorrhage (9.3% vs 3.5%, respectively; P = .01), cortical microinfarcts (20.7% vs 12.9%, respectively; P = .03), and subcortical leukoencephalopathy (20.5% vs 12.1%, respectively; P = .02). Noncarriers of the APOE ε4 allele with severe CAA compared with those without CAA had a higher prevalence of stroke (11.1% vs 3.9%, respectively; OR = 3.8; 95% CI, 1.0-14.6) and hypercholesterolemia (50.0% vs 32.7%, respectively; OR = 2.3; 95% CI, 1.1-4.7).

Conclusions and relevance

Being Hispanic and having had a transient ischemic attack-like episode were predictors of CAA in persons with AD. Less diffuse parenchymal amyloid pathology in persons with severe CAA suggests a difference in β-amyloid trafficking.

Studies have demonstrated associations between cardiovascular factors and Alzheimer disease (AD) with minimal focus on other neurodegenerative diseases. Utilizing cross-sectional data from 17,532 individuals in the National Alzheimer's Coordinating Center, Uniform Data Set, we compared the presence of cardiovascular factors [body mass index (BMI), atrial fibrillation, hypertension, hyperlipidemia, and diabetes] in individuals carrying a diagnosis of Probable AD (ProbAD), Possible AD, vascular dementia, dementia with Lewy bodies (DLB), frontotemporal dementia, Parkinson disease, progressive supranuclear palsy, or corticobasal degeneration, with that of normals. Generalized linear mixed models were fitted with age at visit, gender, and cardiovascular factors as fixed effects and Alzheimer's Disease Centers as random effects. In late life, only BMI of ProbAD and DLB patients was statistically significantly lower than that in normals (P-values <0.001). When accounting for colinearity within cardiovascular factors, a low BMI was a comorbidity of certain dementia etiologies as compared with normals. These data support a concept of disease-specific associations with certain cardiovascular factors.

BACKGROUND: In newborns with hypoxic-ischemic encephalopathy (HIE), the correlation between neonatal neuroimaging and the degree of neurodevelopmental impairment (NDI) is unclear. METHODS: Infants with HIE enrolled in a randomized controlled trial underwent neonatal MRI/MR spectroscopy (MRS) using a harmonized protocol at 4-6 days of age. The severity of brain injury was measured with a validated scoring system. Using proportional odds regression, we calculated adjusted odds ratios (aOR) for the associations between MRI/MRS measures of injury and primary ordinal outcome (i.e., normal, mild NDI, moderate NDI, severe NDI, or death) at age 2 years. RESULTS: Of 451 infants with MRI/MRS at a median age of 5 days (IQR 4.5-5.8), outcomes were normal (51%); mild (12%), moderate (14%), severe NDI (13%); or death (9%). MRI injury score (aOR 1.06, 95% CI 1.05, 1.07), severe brain injury (aOR 39.6, 95% CI 16.4, 95.6), and MRS lactate/n-acetylaspartate (NAA) ratio (aOR 1.6, 95% CI 1.4,1.8) were associated with worse primary outcomes. Infants with mild/moderate MRI brain injury had similar BSID-III cognitive, language, and motor scores as infants with no injury. CONCLUSION: In the absence of severe injury, brain MRI/MRS does not accurately discriminate the degree of NDI. Given diagnostic uncertainty, families need to be counseled regarding a range of possible neurodevelopmental outcomes. IMPACT: Half of all infants with hypoxic-ischemic encephalopathy (HIE) enrolled in a large clinical trial either died or had neurodevelopmental impairment at age 2 years despite receiving therapeutic hypothermia. Severe brain injury and a global pattern of brain injury on MRI were both strongly associated with death or neurodevelopmental impairment. Infants with mild or moderate brain injury had similar mean BSID-III cognitive, language, and motor scores as infants with no brain injury on MRI. Given the prognostic uncertainty of brain MRI among infants with less severe degrees of brain injury, families should be counseled regarding a range of possible neurodevelopmental outcomes.

Introduction

Four new nonproprietary tests were recommended for use in the National Alzheimer's Coordinating Center's Uniform Data Set Neuropsychological Battery. These tests are similar to previous tests but also allow for continuity of longitudinal data collection and wide dissemination among research collaborators.

Methods

A Crosswalk Study was conducted in early 2014 to assess the correlation between each set of new and previous tests. Tests with good correlation were equated using equipercentile equating. The resulting conversion tables allow scores on the new tests to be converted to equivalent scores on the previous tests.

Results

All pairs of tests had good correlation (ρ=0.68 to 0.78). Learning effects were detected for Logical Memory only. Confidence intervals were narrow at each point estimate, and prediction accuracy was high.

Discussion

The recommended new tests are well correlated with the previous tests. The equipercentile equating method produced conversion tables that provide a useful reference for clinicians and researchers.