Utility of the NIH Toolbox for assessment of prodromal Alzheimer's disease and dementia.

INTRODUCTION: The NIH Toolbox Cognition Battery (NIHTB-CB) is a computer-based protocol not yet validated for clinical assessment. METHODS: We administered the NIHTB-CB and traditional neuropsychological tests to 247 Memory Disorders and Alzheimer's Prevention Clinic patients with subjective cognitive decline, mild cognitive impairment, mild dementia due to Alzheimer's disease, and normal cognition. Principal component analysis, partial correlations, and univariate general linear model tests were performed to assess construct validity. Discriminant function analyses compared classification accuracy. RESULTS: Principal component analysis identified three conceptually coherent factors: memory (MEMNIH), executive function (EFNIH), and crystallized intelligence (CINIH). These factors were strongly associated with corresponding traditional tests and differed across diagnostic groups as expected. Both NIHTB and traditional batteries yielded strong overall discriminative ability (>80%). DISCUSSION: The NIHTB-CB is a valid method to assess neurocognitive domains pertinent to aging and dementia and has utility for applications in a memory clinic setting.

Comparing brain amyloid deposition, glucose metabolism, and atrophy in mild cognitive impairment with and without a family history of dementia.

This study compares the degree of brain amyloid-ß (Aß) deposition, glucose metabolism, and grey matter volume (GMV) reductions in mild cognitive impairment (MCI) patients overall and as a function of their parental history of dementia. Ten MCI with maternal history (MH), 8 with paternal history (PH), and 24 with negative family history (NH) received 11C-PiB and 18F-FDG PET and T1-MRI as part of the Alzheimer's Disease Neuroimaging Initiative. Statistical parametric mapping, voxel based morphometry, and Z-score mapping were used to compare biomarkers across MCI groups, and relative to 12 normal controls. MCI had higher PiB retention, hypometabolism, and GMV reductions in Alzheimer-vulnerable regions compared to controls. Biomarker abnormalities were more pronounced in MCI with MH than those with PH and NH. After partial volume correction of PET, Aß load exceeded hypometabolism and atrophy with regard to the number of regions affected and magnitude of impairment in those regions. Hypometabolism exceeded atrophy in all MCI groups and exceeded Aß load in medial temporal and posterior cingulate regions of MCI MH. While all three biomarkers were abnormal in MCI compared to controls, Aß deposition was the most prominent abnormality, with MCI MH having the greatest degree of co-occurring hypometabolism.

Reduced mitochondria cytochrome oxidase activity in adult children of mothers with Alzheimer's disease.

Biomarker studies demonstrate inheritance of glucose hypometabolism and increased amyloid-ß deposition in adult offspring of mothers, but not fathers, affected by late-onset Alzheimer's disease (LOAD). The underlying genetic mechanisms are unknown. We investigated whether cognitively normal (NL) individuals with a maternal history of LOAD (MH) have reduced platelet mitochondrial cytochrome oxidase activity (COX, electron transport chain complex IV) compared to those with paternal (PH) or negative family history (NH). Thirty-six consecutive NL individuals (age 55 ± 15 y, range 27-71 y, 56% female, CDR = 0, MMSE ≥28, 28% APOE-4 carriers), including 12 NH, 12 PH, and 12 MH, received a blood draw to measure platelet mitochondrial COX activity. Citrate synthase activity (CS) was measured as a reference. Groups were comparable for clinical and neuropsychological measures. We found that after correcting for CS, COX activity was reduced by 29% in MH compared to NH, and by 30% in MH compared to PH (p ≤ 0.006). Results remained significant controlling for age, gender, education, and APOE. No differences were found between PH and NH. COX measures discriminated MH from the other groups with accuracy ≥75%, and relative risk ≥3 (p ≤ 0.005). Among NL with LOAD-parents, only those with MH showed reduced COX activity in platelet mitochondria compared to PH and NH. The association between maternal history of LOAD and systemic COX reductions suggests transmission via mitochondrial DNA, which is exclusively maternally inherited in humans.

Toward the validation of functional neuroimaging as a potential biomarker for Alzheimer's disease: implications for drug development.

Despite investments carried out in the research since Alzheimer's disease (AD) was firstly defined as an isolated clinical entity, there is still a lack of appropriate cure and effective therapies to halt or slow the disease progression. While fundamental research has provided a better characterization of AD, much remains to be done for the development of new biological treatment strategies. It is now being debated whether functional neuroimaging (FNI) could help improve diagnostic accuracy and become a possible biomarker of AD. The primary purpose of this review was to determine whether data already published in the literature meet formal technology assessment standards for using regional cerebral blood flow (rCBF) or glucose metabolism (rCMRGlu) as a biomarker for AD. The secondary purpose was to identify any remaining gaps that might need to be systematically addressed before drug developers and regulators accept FNI as a biomarker for AD. The present paper reviews the literature regarding metabolic positron emission tomography (PET) and perfusion single photon emission computed tomography (SPECT) studies in AD. There is evidence that treatment with acetylcholinesterase inhibitors (AChEI) leads to changes in brain physiology within the brain regions critical to AD pathology, i.e. the temporal, parietal and frontal association cortex. However, a thorough analysis combining functional and neuropsychological data has not yet been attempted, and much research is needed to validate the role of FNI as a surrogate endpoint for AD clinical trials.