Misclassification Is Likely in the Assessment of Mild Cognitive Impairment

Abstract

We estimated the relative frequency of isolated memory impairment versus isolated and comorbid impairment in executive control function (ECF). One hundred and ninety-three noninstitutionalized residents of a single Comprehensive Care Retirement Community (mean age 79.2 years) were investigated. The subjects were tested with multiple measures of memory and ECF. Test scores were standardized to minimize scaling effects. ‘Impairment’ was defined as performance ≤1.5 standard deviations below the mean for the entire sample (i.e., a z score ≤–1.5). Disability was estimated as the sum of self-reported activities of daily living and instrumental activities of daily living. The cognitive test performance was significantly associated with functional impairment, independently of age. ECF and memory measures were significantly intercorrelated. Both were significantly and independently associated with disability ratings. 6–10% of the subjects had memory impairment; 25–35% of the memory-impaired subjects had comorbid ECF impairments. An additional 4–7% of the subjects had isolated ECF impairment. A significant fraction of the cases otherwise meeting the criteria for ‘mild cognitive impairment’ may have comorbid ECF impairment. This raises the issue of whether they might be more properly classified as ‘demented’. In addition, isolated ECF impairment may affect almost as many persons as isolated memory impairment. Isolated ECF impairment is not consistent with the natural history of preclinical Alzheimer’s disease, suggests other conditions, and can be disabling, independently of age and/or memory loss.

Index Variables for Studying Outcomes in Vascular Cognitive Impairment

“…As elsewhere, we found a modest advantage to weighting for predictive performance [14,43] . In this study, a 5% increase in the AUC was observed for a VCI diagnosis and an over 10% increase in the AUC was observed for survival outcomes.…”

Determinantes del riesgo de desnutrición en los adultos mayores de la comunidad: análisis secundario del estudio Salud, Bienestar y Envejecimiento (SABE) en México

“…Este hallazgo podría estar relacionado con la elevada prevalencia encontrada de diabetes e hipertensión, enfermedades crónico-degenerativas asociadas con lesiones vasculares "estratégicas" en determinados circuitos cerebrales (45) que pudieran manifestarse en problemas en la realización de funciones ejecutivas. Se ha descrito que el deterioro cognoscitivo con cambios en el control de las funciones ejecutivas es suficiente para explicar el deterioro funcional general, y que las personas con deterioro cognoscitivo amnésico tienen menor riesgo de llegar a la demencia que las que presentan problemas en el control de funciones ejecutivas (46,47). En un estudio realizado por Royall y colaboradores se describe que los cambios en el control de las funciones ejecutivas están relacionadas con las actividades instrumentales de la vida diaria y, por lo tanto, con el deterioro de la capacidad funcional (48).…”

Factors affecting statistical power in the detection of genetic association

“…One example comes from the study of Alzheimer disease. Some researchers may use clinical dementia tests as a means of diagnosing Alzheimer disease (82,83). However, not all individuals who show clinical dementia necessarily develop Alzheimer disease (82).…”

“…Some researchers may use clinical dementia tests as a means of diagnosing Alzheimer disease (82,83). However, not all individuals who show clinical dementia necessarily develop Alzheimer disease (82). Another example of phenotype error is the one previously mentioned: use of the PSA test for diagnosis of male prostate cancer (14).…”