arXiv subjects

Philip Scheltens

Publications and source records attributed to Philip Scheltens.

3 recordsLinked to original sources

arXiv2020

The influence of diversity on the measurement of functional impairment: An international validation of the Amsterdam IADL Questionnaire in 8 countries

INTRODUCTION: To understand the potential influence of diversity on the measurement of functional impairment in dementia, we aimed to investigate possible bias caused by age, gender, education, and cultural differences. METHODS: 3,571 individuals (67.1 {\pm} 9.5 years old, 44.7% female) from the Netherlands, Spain, France, United States, United Kingdom, Greece, Serbia and Finland were included. Functional impairment was measured using the Amsterdam IADL Questionnaire. Item bias was assessed using differential item functioning (DIF) analysis. RESULTS: There were some differences in activity endorsement. A few items showed statistically significant DIF. However, there was no evidence of meaningful item bias: effect sizes were low (ΔR2 range 0-0.03). Impact on total scores was minimal. DISCUSSION: The results imply a limited bias for age, gender, education and culture in the measurement of functional impairment. This study provides an important step in recognizing the potential influence of diversity on primary outcomes in dementia research.

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arXiv2017

Blood-based metabolic signatures in Alzheimer's disease

Introduction: Identification of blood-based metabolic changes might provide early and easy-to-obtain biomarkers. Methods: We included 127 AD patients and 121 controls with CSF-biomarker-confirmed diagnosis (cut-off tau/A$β_{42}$: 0.52). Mass spectrometry platforms determined the concentrations of 53 amine, 22 organic acid, 120 lipid, and 40 oxidative stress compounds. Multiple signatures were assessed: differential expression (nested linear models), classification (logistic regression), and regulatory (network extraction). Results: Twenty-six metabolites were differentially expressed. Metabolites improved the classification performance of clinical variables from 74% to 79%. Network models identified 5 hubs of metabolic dysregulation: Tyrosine, glycylglycine, glutamine, lysophosphatic acid C18:2 and platelet activating factor C16:0. The metabolite network for APOE $ε$4 negative AD patients was less cohesive compared to the network for APOE $ε$4 positive AD patients. Discussion: Multiple signatures point to various promising peripheral markers for further validation. The network differences in AD patients according to APOE genotype may reflect different pathways to AD.

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arXiv2017

Detecting functional decline from normal ageing to dementia: development and validation of a short version of the Amsterdam IADL Questionnaire

INTRODUCTION: Detecting functional decline from normal ageing to dementia is relevant for diagnostic and prognostic purposes. Therefore, the Amsterdam IADL Questionnaire (A-IADL-Q) was developed: a 70-item proxy-based tool with good psychometric properties. We aimed to design a short version whilst preserving its psychometric quality. METHODS: Study partners of subjects (n=1355), ranging from cognitively normal to dementia subjects, completed the original A-IADL-Q. We selected the short version items using a stepwise procedure combining missing data, Item Response Theory and input from respondents and experts. We investigated internal consistency of the short version as well as concordance with the original version. To assess its construct validity, we additionally investigated concordance between the short version and the Mini-Mental State Examination (MMSE) and Disability Assessment for Dementia (DAD). Lastly, we investigated differences in IADL scores between diagnostic groups across the dementia spectrum. RESULTS: We selected 30 items covering the entire spectrum of IADL functioning. Internal consistency (.98) and concordance with the original version (.97) were very high. Concordance with the MMSE (.72) and DAD (.87) scores was high. IADL impairment scores increased across the spectrum from normal cognition to dementia. DISCUSSION: The A-IADL-Q Short Version (A-IADL-Q-SV) consists of 30 items. The A-IADL-Q-SV has maintained the psychometric quality of the original A-IADL-Q. As such, it is a concise measure of functional decline.

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