Compensatory mechanisms in higher-educated subjects with Alzheimer's disease: a study of 20 years of cognitive decline.

A better knowledge of long-term trajectories of cognitive decline is a central feature of the study of the process leading to Alzheimer's dementia. Several factors may mitigate such decline, among which is education, a major risk factor for Alzheimer's disease. The aim of our work was to compare the pattern and duration of clinical trajectories before Alzheimer's dementia in individuals with low and high education within the PAQUID cohort involving 20 years of follow-up. The sample comprises 442 participants with incident Alzheimer's disease (27.2% were male)--171 with low education (mean age=86.2 years; standard deviation=5.3 years) and 271 with higher education (mean age=86.5; standard deviation=5.4)--and 442 control subjects matched according to age, sex and education. At each visit and up to the 20-year follow-up visit, several cognitive and clinical measures were collected and incident cases of Alzheimer's disease clinically diagnosed. The evolution of clinical measures in pre-demented subjects and matched controls was analysed with a semi-parametric extension of the mixed effects linear model. The results show that the first signs of cognitive decline occurred 15 to 16 years before achieving dementia threshold in higher-educated subjects whereas signs occurred at 7 years before dementia in low-educated subjects. There seemed to be two successive periods of decline in higher-educated subjects. Decline started ∼15 to 16 years before dementia with subtle impairment restricted to some cognitive tests and with no impact during the first 7 to 8 years on global cognition, cognitive complaints, or activities of daily living scales. Then, ∼7 years before dementia, global cognitive abilities begin to deteriorate, along with difficulties dealing with complex activities of daily living, the increase in self-perceived difficulties and depressive symptoms. By contrast, lower-educated subjects presented a single period of decline lasting ∼7 years, characterized by decline concomitantly affecting specific and more global cognitive function along with alteration in functional abilities. This study demonstrates how early cognitive symptoms may emerge preceding Alzheimer's dementia particularly in higher-educated individuals, for whom decline occurred up to 16 years before dementia. It also demonstrates the protective role of education in the clinical trajectory preceding Alzheimer's dementia. We suggest that the initial decline in cognition occurs at the onset of comparable Alzheimer's disease pathology in both groups, and is associated with immediate decline to dementia in the lower education group. In contrast, higher education protects against further cognitive decline for ∼7 years until pathology becomes more severe.

[The DMS 48: norms and diagnostic proprieties for Alzheimer's disease in elderly population from the AMI cohort study]. / Test du DMS 48 : normes chez les sujets âgés et propriétés de détection de la maladie d'Alzheimer dans la cohorte AMI.

UNLABELLED: The DMS 48 is a visual recognition memory test designed to detect memory changes in early Alzheimer's disease (AD). The aim of this study was to produce normative scores for this test and to assess its psychometric properties in the detection of AD by comparison with a widely used test of verbal episodic memory: the story recall task of the Wechsler memory scale. Methods. Data were collected in a sample of 1002 agricultural retirees, aged 65 years and over, included in the AMI study, a population-based cohort conducted in Southwestern France. The sample used to establish normative data included 750 non-demented elderly while the sample used to study the properties of the test to detect AD included 751 participants whose 34 with AD. To assess AD detection accuracy, DMS 48 was compared to the Wechsler story recall task. Results. Age, sex, and education were significantly associated with DMS 48 performances. Therefore, normative scores were calculated according to sex, age, and educational level, and described by percentiles. Regarding the test properties for AD detection, DMS 48 presented a good balance between sensitivity (Se) and specificity (Sp) both for immediate (Se=70.6%; Sp=79.6%) and delayed recall (Se=79.4%; Sp=72.9%). It also showed high negative predictive values, around 98.5% for both recalls. Detection values were roughly similar to that of Wechsler story recall task. CONCLUSION: The DMS 48 seems to be as reliable as the Wechsler story recall task with similar detection properties. The DMS 48 is a test easy to administer in clinical situations and could be a helpful tool for AD screening.

Normative data for the Mini-Mental State Examination, the Free and Cued Selective Reminding Test and the Isaacs Set Test for an older adult Mexican population: the Coyoacán cohort study.

UNLABELLED: The Mini-Mental State Examination (MMSE), the Free and Cued Selective Reminding Test (FCSRT), and the Isaacs Set Test (IST) are useful instruments in the neuropsychological assessment of older individuals. Several versions of these tests exist in Spanish but normative data specifically set up for Mexican older adult population are missing although Mexico is the country containing the largest population of Spanish speakers and is undergoing a demographic transition with its aging population. Therefore, the aim of the present work was to produce age, educational level, and gender-adjusted normative scores for these tests for the population of older adults living in Mexico. METHODS: Data were collected from a sample of 1047 subjects aged 70 years and over who participated in the Coyoacán cohort study, a population-based cohort study conducted in Mexico City. RESULTS: Normative scores, presented in percentiles, were calculated according to age (70-79 and 80 years and over), educational level (0 years of schooling vs. 1-5 years of schooling vs. 6 and more years of schooling), and gender. CONCLUSION: This work provides norms for the MMSE, the FCSRT, and the IST which should be useful in clinical practice and helpful to better interpret the performances of Mexican older people consulting for memory troubles.