Mild Dementia Subjects Research Articles

Brain age gap difference between healthy and mild dementia subjects: Functional network connectivity analysis.

Brain age gap, the difference between an individual's brain predicted age and their chronological age, is used as a biomarker of brain disease and aging. To date, although previous studies used structural magnetic resonance imaging (MRI) data to predict brain age, less work has used functional network connectivity (FNC) estimated from functional MRI to predict brain age and its association with Alzheimer's disease progression. This study used FNC estimated from 951 normal cognitive functions (NCF) individuals aged 42-95 years to train a support vector regression (SVR) to predict brain age. In the next step, we tested the trained model on two unseen datasets, including NCF and mild dementia (MD) subjects with similar age distribution (between 50-80 years old, N=70). The mean brain age gap for the NCF and MD groups was -2.25 and 2.08, respectively. We also found a significant difference between the brain age gap of NCF and MD groups. This piece of evidence introduces the brain age gap estimated from FNC as a biomarker of Alzheimer's disease progression.

From Face-to-Face to Home-to-Home: Validity of a Teleneuropsychological Battery.

Background:Over the last decade, teleneuropsychology has increased substantially. There is a need for valid neuropsychological batteries to be administered home-to-home. Since 2006, the neuropsychological battery of Fundació ACE (NBACE) has been administered face-to-face in our clinical settings. Recently, we adapted the NBACE for teleneuropsychology use to be administered home-to-home (NBACEtn).Objective:The aims of the present study are: 1) to determine the home-to-home NBACE equivalence compared to its original face-to-face version; and 2) to examine home-to-home NBACE discriminant capacity by differentiating among cognitively healthy, mild cognitive impairment, or mild dementia subjects and comparing it with the face-to-face version.Methods:Data from 338 individuals assessed home-to-home (NBACEtn) were contrasted with 7,990 participants assessed with its face-to-face version (NBACE). Exploratory and confirmatory factorial structure, and invariance analysis of the two versions of the battery were performed.Results:Exploratory and confirmatory factor analysis supported the four-factor model (attention, memory, executive, and visuospatial/constructional functions). Configural, metric, and scalar measurement invariance was found between home-to-home and face-to-face NBACE versions. Significant differences in most of the neuropsychological variables assessed were observed between the three clinical groups in both versions of administration. No differences were found between the technological devices used by participants (computer or tablet and mobile devices).Conclusion:For the first time, invariance analysis findings were addressed by determining a teleneuropsychological battery’s equivalence in comparison with its face-to-face version. This study amplifies the neuropsychological assessment’s applicability using a home-to-home format, maintaining the original measure’s structure, interpretability, and discriminant capacity.

Does informant-based reporting of cognitive symptoms predict amyloid positivity on positron emission tomography?

IntroductionResearchers are searching for clinical instruments to predict amyloid positivity for disease classification. Informant-based reports could detect disease status. This study compares subjective memory complaints captured by informant-based reports between positron emission tomography (PET)–positive and PET-negative patients and hypothesizes that amyloid PET positivity associates with increased informant-based cognitive complaints. MethodsNinety-eight amnestic mild cognitive impairment or mild dementia subjects were studied. Subjective report was captured by the informant-driven Alzheimer's Questionnaire (AQ) administered before PET. Differences in demographics and AQ score by diagnostic status and amyloid status were measured, and a receiver-operating characteristic curve was calculated. ResultsSixty-five mild cognitive impairment/Alzheimer's disease amyloid PET-positive and 33 amyloid PET-negative subjects were included. AQ was significantly higher (12.51 ± 4.95) for amyloid PET-positive subjects (9.06 ± 3.65; P = .001). ConclusionsAmyloid PET-positive subjects with Alzheimer's disease or mild cognitive impairment have more informant-based reports of cognitive decline, indicating utility for a brief informant measure.

CEREBROSPINAL FLUID TAU/AMYLOID β42 RATIO CORRELATES TO CEREBRAL ATROPHY IN AD

Duits and colleagues identified the ratio of tau/Aβ42 of > 0.52 to be a robust cerebrospinal fluid (CSF) biomarker for AD. However, the correlation of this ratio to neuroimaging measures is currently lacking. We investigated the usefulness of CSF Aβ42 and tau/Aβ42 in differentiating AD patients from cognitively normal subjects and other dementias in reference its neuroimaging correlates. 24 mild dementia subjects with complete neuropsychological, CSF and neuroimaging were included in the study. Subjects were first classified based on their β-Amyloid levels (cut-off of 487 pg/ml): 8 low β-Amyloid and 16 had levels within normal limits. They were then classified in accordance to their Duits's ratio: 14 Duits's ratio positive and 10 negative. We applied the voxel-based morphometry protocol using the VBM8 in Statistical Parametric Mapping (SPM8). To examine group differences, we built a voxel-wise Analysis of Covariates (ANCOVA) models with grey matter as the dependent variables, group membership (β-Amyloid low or normal; and Duits's positive or negative) as the independent variable. Age and gender were added as covariates. Statistical significance was obtained for height threshold of p < 0.001 and extent threshold of 100 voxels. Significant clusters in the grey matter were anatomically identified using the Automated Anatomical Labelling (AAL) atlas (Fig 1.) Marsbar was used to extract the significant grey matter clusters. Domain z-scores were calculated. SPSS was used to perform other statistical analyses. 24 patients were studied (Table 1). There were no significant clusters when comparing between β-Amyloid low and normal subjects in either contrasts. However, Duits's positive subjects showed significant atrophy in the left middle frontal, right inferior and superior temporal, right parahippocampal, and bilateral precuneus regions compared to those who were Duits's negative. MMSE and MoCA scores were also significantly lower in the Duits's positive than negative, which were significantly associated with the atrophied regions. Correlation analyses also revealed the negative associations between episodic memory and executive function with left middle frontal, right superior temporal cortices, and bilateral precuneus.

Pre-MCI and MCI: Neuropsychological, Clinical, and Imaging Features and Progression Rates

To compare clinical, imaging, and neuropsychological characteristics and longitudinal course of subjects with pre-mild cognitive impairment (pre-MCI), who exhibit features of MCI on clinical examination but lack impairment on neuropsychological examination, to subjects with no cognitive impairment (NCI), nonamnestic MCI (naMCI), amnestic MCI (aMCI), and mild dementia. For 369 subjects, clinical dementia rating sum of boxes (CDR-SB), ApoE genotyping, cardiovascular risk factors, parkinsonism (UPDRS) scores, structural brain MRIs, and neuropsychological testing were obtained at baseline, whereas 275 of these subjects received an annual follow-up for 2-3 years. At baseline, pre-MCI subjects showed impairment on tests of executive function and language, higher apathy scores, and lower left hippocampal volumes (HPCV) in comparison to NCI subjects. Pre-MCI subjects showed less impairment on at least one memory measure, CDR-SB and UPDRS scores, in comparison to naMCI, aMCI and mild dementia subjects. Follow-up over 2-3 years showed 28.6% of pre-MCI subjects, but less than 5% of NCI subjects progressed to MCI or dementia. Progression rates to dementia were equivalent between naMCI (22.2%) and aMCI (34.5%) groups, but greater than for the pre-MCI group (2.4%). Progression to dementia was best predicted by the CDR-SB, a list learning and executive function test. This study demonstrates that clinically defined pre-MCI has cognitive, functional, motor, behavioral and imaging features that are intermediate between NCI and MCI states at baseline. Pre-MCI subjects showed accelerated rates of progression to MCI as compared to NCI subjects, but slower rates of progression to dementia than MCI subjects.

The Stroop color-word test: indicator of dementia severity.

The Stroop color-word test was used to examine patterns of cognitive decline in Alzheimer-type dementia (ATD) and non-Alzheimer dementia. Slowing on color naming and word reading was observed, and was greater in moderate than in mild dementia subjects. However, error scores were unrelated to dementia type and severity. The Stroop interference effect, measured with reaction time, was high in individuals with mild ATD and mild non-Alzheimer dementia. In contrast, the more severely impaired ATD subjects showed less Stroop interference effect than mildly impaired subjects when the reaction time was adjusted for color naming performance. These findings are attributed to variation in speed-accuracy tradeoff for the patient groups due to differences in information processing deficits, linguistic impairment, and attitudes to errors. This study demonstrates the importance of partialling out underlying deficits for the understanding of complex cognitive processes in dementia.

Verbal fluency in aging and dementia

abstract Fluency tasks from two categories, animals and words beginning with a specified letter (“C”, “F”, “L”), were administered to normal elderly and to elderly with mild or moderate-to-severe senile dementia of the Alzheimer type. In both tasks, normals were superior to both dementia groups, while the mild dementia group was less impaired. Normals and mild dementia subjects retrieved more animal names than “CFL” words. Compared with normals, mild dementia subjects showed a greater performance decrement on the “CFL” words task than on animal naming. Moderate-to-severe dementia subjects showed no difference between tasks. Results suggest that (1) category structure influences retrieval processes, (2) components of the structure are affected differentially during the disease process.