This study aimed to investigate psychometric properties and enhance precision of the 16-item Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE-16) up to interval-level scale using Rasch methodology.

Partial Credit Rasch model was applied to the IQCODE-16 scores using longitudinal data spanning 10 years of biennial follow-up.

Community-dwelling older adults aged 70–90 years and their informants, living in Sydney, Australia, participated in the longitudinal Sydney Memory and Ageing Study (MAS).

The sample included 400 participants of the MAS aged 70 years and older, 109 out of those were diagnosed with dementia 10 years after the baseline assessment.

The IQCODE-16.

Initial analysis indicated excellent reliability of the IQCODE-16, Person Separation Index (PSI) = 0.92, but there were four misfitting items and local dependency issues. Combining locally dependent items into four super-items resulted in the best Rasch model fit with no misfitting or locally dependent items, strict unidimensionality, strong reliability, and invariance across person factors such as participants’ diagnosis and relationship to their informants, as well as informants’ age and sex. This permitted the generation of conversion algorithms to transform ordinal scores into interval data to enhance precision of measurement.

The IQCODE-16 demonstrated strong reliability and satisfied expectations of the unidimensional Rasch model after minor modifications. Ordinal-to-interval transformation tables published here can be used to increase accuracy of the IQCODE-16 without altering its current format. These findings could contribute to enhancement of precision in assessing clinical conditions such as cognitive decline in older people.

Low and middle-income countries like India anticipate rapid population aging and increases in dementia burden. In India, dementia screening scales originally developed in other contexts need to be assessed for feasibility and validity, given the number of different languages and varying levels of literacy and education.

Using data from the Longitudinal Aging Study in India-Diagnostic Assessment of Dementia (N = 4,028), we characterize the performance of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE). We described patterns and correlates of missingness, evaluated the psychometric properties of the scale, and assessed criterion validity against the Hindi Mental State Examination (HMSE) using linear regression.

Several IQCODE items had high levels of missingness, which was associated with urbanicity, respondent’s gender, and informant’s generation (same vs. younger generation). Full IQCODE scores showed strong criterion validity against the HMSE; each 1-point increase in IQCODE score was associated with a 3.03-point lower score on the HMSE, controlling for age, gender, and urbanicity. The statistically significant association between IQCODE and HMSE was stronger in urban than rural settings (p-value for interaction = 0.04). Associations between IQCODE and HMSE remained unchanged after removing the three items with the highest levels of differential missingness (remembering addresses and telephone numbers, ability to work with familiar machines, ability to learn to use new gadget or machine).

Findings raise questions about the value of including items with high proportions of missingness, which may signal cultural irrelevance, while removing them did not affect criterion validity.

To clarify the characteristic of impaired and unimpaired Instrumental Activities of daily living (IADL) processes with the severity of cognitive impairment in community-dwelling older adults with Alzheimer’s disease (AD) using the Process Analysis of Daily Activity for Dementia (PADA-D).

Cross-sectional study.

13 medical and care centers in Japan.

115 community-dwelling older adults with AD.

The severity of cognitive impairment was classified by Mini-Mental State Examination (20 ≥ mild group, 20 < moderate group ≥ 10, 10 < severe group), and IADL scores and eight IADL items in PADA-D were compared among three groups after adjusting for covariates. Rate of five feasible processes included in each IADL of PADA-D was compared.

IADL score showed a decrease in independence with the severity of AD except for Use modes of transportation and Managing finances, which was especially pronounced in Shopping (F = 25.58), Ability to use the telephone (F = 16.75), and Managing medication (F = 13.1). However, when the PADA-D was examined by process, some processes that were impaired and unimpaired with the severity of cognitive impairment were clear. For example, Plan a meal was impaired (ES = 0.29) with the severity, but Prepare the food was not in Cooking performance.

We suggested that detailed process analysis in IADLs can clarify the characteristic of processes that are impaired and unimpaired with the severity of cognitive impairment in older adults with AD living in the community. Our findings may be useful for rehabilitation and care in IADL to continue living at home.

The literature on Alzheimer’s disease (AD) provides little data about long-term cognitive course trajectories. We identify global cognitive outcome trajectories and associated predictor variables that may inform clinical research and care.

Data derived from the National Alzheimer’s Coordinating Center (NACC) Uniform Data Set were used to examine the cognitive course of persons with possible or probable AD, a Mini-Mental State Examination (MMSE) of ≥10, and complete annual assessments for 5 years.

Thirty-six Alzheimer’s Disease Research Centers.

Four hundred and fourteen persons.

We used a hybrid approach comprising qualitative analysis of MMSE trajectory graphs that were operationalized empirically and binary logistic regression analyses to assess 19 variables’ associations with each trajectory. MMSE scores of ±3 points or greater were considered clinically meaningful.

Five distinct cognitive trajectories were identified: fast decliners (32.6%), slow decliners (30.7%), zigzag stable (15.9%), stable (15.9%), and improvers (4.8%). The decliner groups had three subtypes: curvilinear, zigzag, and late decline. The fast decliners were associated with female gender, lower baseline MMSE scores, a shorter illness duration, or receiving a cognitive enhancer. An early MMSE decline of ≥3 points predicted a worse outcome. A higher rate of traumatic brain injury, the absence of an ApoE ϵ4 allele, and male gender were the strongest predictors of favorable outcomes.

Our hybrid approach revealed five distinct cognitive trajectories and a variegated pattern within the decliners and stable/improvers that was more consistent with real-world clinical experience than prior statistically modeled studies. Future investigations need to determine the consistency of the distribution of these categories across settings.

Cognitive decline is common in the old age, but some evidence suggests it may already occur during adulthood. Previous studies have linked age, gender, educational attainment, depression, physical activity, and social engagement to better cognitive performance over time. However, most studies have used global measures of cognition, which could mask subtle changes in specific cognitive domains. The aim of this study is to examine trajectories of recent and delayed memory recall from a variable-centered perspective, in order to elucidate the impact of age, gender, educational attainment, depression, physical activity, and social engagement on recent and delayed memory both at initial time and across a 10-year period.

The sample was formed by 56,616 adults and older adults that participated in waves 4 to 8 of the Survey of Health, Aging and Retirement in Europe (SHARE).

We used latent growth modeling to establish latent recent and delayed memory trajectories, and then tested the effects of the aforementioned covariates on the latent intercept and slopes.

Results showed that both recent and delayed recall display a quadratic trajectory of decline. All covariates significantly explained initial levels of immediate and delayed recall, but only a few had statistically significant effects on the slope terms.

We discuss differences between present results and those previously reported in studies using a person-centered approach. This study provides evidence of memory decline during adulthood and old adulthood. Further, results provide support for the neural compensation reserve theory.