Association of the cognitive reserve with the age of onset of mild cognitive impairment and dementia in patients with or Alzheimer’s disease. Antioquia, Colombia.

Background The cognitive reserve (CR) has been associated with the extension/compensation of the mental functioning of individuals affected by a neurodegenerative disease in the early stages of the disease. Most of the analyses evaluating CR are in high-income countries, while there is a lack of capturing the variability related to low-middle-income environments such as Colombia. Objective: to analyze the relationship between CR and the age of onset of MCI and/or dementia by Alzheimer?s disease (AD) in patients from Antioquia-Colombia. Method A retrospective cohort study of 194 individuals. Clinical and socioeconomic characteristics were described using absolute and relative frequencies, followed by a mixed principal component analysis to represent the CR. A Varimax rotation was used for its interpretation, generating Z scores for the CR and the resulting dimensions. CR was categorized according to the median as high or low. This categorization aims to assess differences in the onset time of MCI and dementia by AD for the survival analysis and Cox regression with multiple imputation models (m = 30). We also examined all data to estimate the raw effect and adjusted for age, sex, and area. Results from 194 patients, 151 informed the age of onset of MCI, and 165 were later diagnosed with dementia by AD. There were differences between 5 and 9 years in the median age of onset of MCI and dementia by AD, with a later onset for patients with high CR. The CR hazard ratios (HR) were 1.05 and 0.97 for MCI and dementia, respectively. The ratio for the total score tended to be null after adjustment with confounding variables. However, its dimensions remained significant. Specifically, the HRs for an academic position, growing environment, and family status increased the speed of onset of the outcomes for MCI: 1.43, 1.06, and 1,72 and dementia: 1.40, 1.12, and 1.68. Conclusion the onset times of the MCI and dementia were five years later in subjects with higher CR. Thus, a high academic position, a protective growth environment, and a family status that favors social relationships were associated with the reduction in clinical symptoms of AD since the early stages.