Objectives: There is strong evidence about the association between low socioeconomic status (SES) and higher risk of dementia. However, it has not been conveniently addressed so far the role of SES on the incidence of mild cognitive impairment (MCI). This study examines the impact of individual and neighbourhood dimensions of SES, as well as their interaction, on the risk of developing MCI in a sample of older adults. Method: Data from the Vallecas Project cohort, an ongoing community-based longitudinal study for early detection of cognitive impairment and dementia, were used to build two indices of SES namely individual and neighbourhood, as well as a global SES as a combination of both, and to investigate their effects on MCI conversion by means of a multivariate-adjusted Cox proportional hazard model. Results: A total of 1180 participants aged 70 years and older were enrolled in this study. Of these, 199 cases of MCI (16.9%) were diagnosed at any point of the follow-up. The individual and neighbourhood dimensions of SES played different roles in the dynamics of the MCI occurrence through aging. Most importantly, the risk of developing MCI was almost double for lower SES quartiles when compared to the highest one. Conclusion:The incidence of MCI in older adults was related to both individual characteristics and socioeconomic context. Public health strategies should be holistic and focus not only on promoting the classical individual preventive measures, but also on reducing social inequalities to foster healthy aging and reduce dementia burden.

IMPORTANCE: There is strong evidence about the association between low socioeconomic status (SES) and higher risk of dementia. However, it has not been conveniently addressed so far the role of SES on the incidence of Mild Cognitive Impairment (MCI) which is considered a prodromal stage of latter dementia.OBJECTIVE: To examine the impact of individual and neighborhood dimensions of SES, as well as their interaction, on the risk of developing MCI in a sample of older adults that were followed-up for seven years.DESIGN, SETTING, AND PARTICIPANTS: Data from the Vallecas Project cohort, an ongoing community-based longitudinal study for early detection of cognitive impairment and dementia, were used to build two indices of SES namely individual and neighborhood, as well as a global SES as a combination of both, and to investigate their effects on MCI conversion by means of a multivariate-adjusted Cox proportional hazard model.MAIN OUTCOMES AND MEASURES: Based on data referred to as individual-level (one´s educational attainment, occupation, parent´s level of education) and neighborhood-level (district´s income, unemployment rate, housing price, percentage of people with no formal qualifications, with higher education, and with white-collar employs) different composite measures of SES were built and quartiles were considered for further analyses. MCI diagnoses were agreed between neurologists and neuropsychologists at consensus meetings.RESULTS: 1180 participants aged 70 years and older were enrolled in this study (mean age at baseline, 74.9 years; 63.5% females). Of these, 199 cases of MCI (16.9%) were diagnosed at any point of the follow-up. The individual and neighborhood dimensions of SES played different roles in the dynamics of the MCI occurrence through ageing. Most importantly, the risk of developing MCI was almost double for lower SES quartiles when compared to the highest one.CONCLUSIONS AND RELEVANCE: The incidence of MCI in older adults was related to both individual characteristics and socioeconomic context. Public health strategies should be holistic and focus not only on promoting the classical individual preventive measures, but also on reducing social inequalities as a means of fostering healthy ageing and reducing dementia burden.