Individual and Area-Based Socioeconomic Factors Associated With Dementia Incidence in England: Evidence From a 12-Year Follow-up in the English Longitudinal Study of Ageing

Abstract

Importance: Lower educational attainment is associated with a higher risk of dementia. However, less clear is the extent to which other socioeconomic markers contribute to dementia risk.

Objective: To examine the relationship of education, wealth, and area-based deprivation with the incidence of dementia over the last decade in England and investigate differences between people born in different periods.

Design, setting, and participants: Data from the English Longitudinal Study of Ageing, a prospective cohort study that is representative of the English population, were used to investigate the associations between markers of socioeconomic status (wealth quintiles and the index of multiple deprivation) and dementia incidence. To investigate outcomes associated with age cohorts, 2 independent groups were derived using a median split (born between 1902-1925 and 1926-1943).

Main outcomes and measures: Dementia as determined by physician diagnosis and the Informant Questionnaire on Cognitive Decline in the Elderly.

Results: A total of 6220 individuals aged 65 years and older enrolled in the study (median [interquartile range] age at baseline, 73.2 [68.1-78.3] years; 3410 [54.8%] female). Of these, 463 individuals (7.4%) had new cases of dementia ascertained in the 12 years between 2002-2003 and 2014-2015. In the cohort born between 1926 and 1943, the hazard of developing dementia was 1.68 times higher (hazard ratio [HR] = 1.68 [95% CI, 1.05-2.86]) for those in the lowest wealth quintile compared with those in the highest quintile, independent of education, index of multiple deprivation, and health indicators. Higher hazards were also observed for those in the second-highest quintile of index of multiple deprivation (HR = 1.62 [95% CI, 1.06-2.46]) compared with those in the lowest (least deprived) quintile.

Conclusions and relevance: In an English nationally representative sample, the incidence of dementia appeared to be socioeconomically patterned primarily by the level of wealth. This association was somewhat stronger for participants born in later years.

Figure 1.. Flowchart of the Individuals Included in Analyses

Numbers of excluded persons are nonmutually exclusive. ELSA indicates the English Longitudinal Study of Ageing; IMD, index of multiple deprivations.

Figure 2.. Dementia Incidence Rates Per 1000 Person-Years in Men and Women Presented by Age-Groups in the English Longitudinal Study of Ageing

Error bars indicate 95% CIs.

Figure 3.. Smoothed Hazard Estimates by Age per 1000 Person-Years by Wealth Quintiles in the English Longitudinal Study of Ageing

Wealth quintile 1 indicates the highest level of wealth; quintile 5, the lowest.