RESUMEN
INTRODUCTION: An increasing body of research suggests that stress and allostatic load are related to cognitive dysfunction and neurodegeneration. OBJECTIVES: to determine the relationship between allostatic load (AL) and cognitive status in older adults classified with subjective cognitive decline (SCD) and mild cognitive impairment (MCI). METHODOLOGY: Using the Brazilian Memory and Aging Study (BRAMS) database, we analyzed data from 57 older adults with SCD and MCI. Blood neuroendocrine (cortisol, DHEA-s), inflammatory (C-reactive protein, fibrinogen), metabolic (HbA1c, HDL-cholesterol, total cholesterol, creatinine), and cardiovascular (blood pressure, waist/hip ratio) were transformed into an AL index. RESULTS: Despite a significant difference in the univariate analysis between waist/hip ratio (0.94 in the MCI group vs. 0, 88 in the SCD group, p = 0.03), total cholesterol levels (194 vs. 160, p = 0.02), and AL index (36.9â¯% in the MCI group vs. 27.2â¯% in the SCD group, p = 0.04), AL was not associated with SCD or MCI in the multivariate analysis. CONCLUSION: Our data suggest that different profiles of AL in MCI compared to individuals with SCD could be due to cofounding factors. These findings need to be confirmed in longitudinal studies investigating profiles of AL changes at preclinical and prodromal stages of Alzheimer's disease.
RESUMEN
BACKGROUND: Low-education attainment is associated with worse cognitive performance in multiple sclerosis (MS) patients, and possibly with a lower cognitive reserve and/or increased inflammatory activity. Cognitive reserve refers to the capability of a source of intellectual enrichment in attenuating a negative effect of a disease-related factor; while the inflammatory activity is often related to T2-lesion load (T2-LL) increase. OBJECTIVE: To disentangle the effects of cognitive reserve and an increased T2-LL in MS-patients with low-education levels. METHODS: The study included 136 MS patients and 65 healthy-controls, divided in low-education (12 years or less of school education without obtaining any technical superior degree) and high-education (more than 12 years of school education with technical or superior degree) groups. An extensive battery of neuropsychological tests was applied examining intelligence quotient and six cognitive domains. Test results were z-scored and subjects with z-scores ≤ -1.5 in two or more domains were considered cognitively impaired. To test the factors associated with worse cognitive performance, regression models were applied using average cognition as target; education level, Expanded Disability Status Scale (EDSS), T2-LL, disease duration, age of disease onset, age and gender as predictors. We also tested the correlation between T2-LL and cognition in the groups. To investigate the role of education level as a source of intellectual enrichment/cognitive reserve in different stages of MS, we sub-divided the MS patients in three groups according to the disease duration (less than 5 years, between 5 and 10 years and more than 10 years). RESULTS: Worse average cognition was associated with low-education level, higher T2-LL and male gender. A higher frequency of cognitively impaired patients was observed in MS patients with low-education level, in all stages of the disease. In patients with a disease duration shorter than five years, there was a lower correlation between worse average cognition and T2-LL in the high-education level group, compared to the patients with low-education level; in MS patients with longer disease duration, we observed a stronger correlation between lesion burden and cognitive impairment in both groups. CONCLUSION: Education attainment is a source of intellectual enrichment and can enhance the cognitive reserve in MS patients. The protective effect of a high-education level was stronger in patients with less than five years of disease, suggesting a stronger role of cognitive reserve in short-term disease. In long-term disease we observed a greater impact of increased inflammatory activity on cognition.