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.

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.

Introduction

Neuropathologic assessment is the current "gold standard" for evaluating the Alzheimer's disease (AD), but there is no consensus on the methods used.

Methods

Fifteen unstained slides (8 brain regions) from each of the 14 cases were prepared and distributed to 10 different National Institute on Aging AD Centers for application of usual staining and evaluation following recently revised guidelines for AD neuropathologic change.

Results

Current practice used in the AD Centers Program achieved robustly excellent agreement for the severity score for AD neuropathologic change (average weighted κ = .88, 95% confidence interval: 0.77-0.95) and good-to-excellent agreement for the three supporting scores. Some improvement was observed with consensus evaluation but not with central staining of slides. Evaluation of glass slides and digitally prepared whole-slide images was comparable.

Discussion

AD neuropathologic evaluation as performed across AD Centers yields data that have high agreement with potential modifications for modest improvements.

Introduction

The neuropsychological battery of the Uniform Data Set (UDSNB) was implemented in 2005 by the National Institute on Aging (NIA) Alzheimer Disease Centers program to measure cognitive performance in dementia and mild cognitive impairment due to Alzheimer Disease. This paper describes a revision, the UDSNB 3.0.

Methods

The Neuropsychology Work Group of the NIA Clinical Task Force recommended revisions through a process of due diligence to address shortcomings of the original battery. The UDSNB 3.0 covers episodic memory, processing speed, executive function, language, and constructional ability. Data from 3602 cognitively normal participants in the National Alzheimer Coordinating Center database were analyzed.

Results

Descriptive statistics are presented. Multivariable linear regression analyses demonstrated score differences by age, sex, and education and were also used to create a normative calculator available online.

Discussion

The UDSNB 3.0 neuropsychological battery provides a valuable non proprietary resource for conducting research on cognitive aging and dementia.