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Association between social class and cognitive health outcomes in older adults: Systematic review and meta‐analysis of longitudinal studies
Author(s) -
Bodryzlova Yuliya,
Belanger Emmanuelle,
Moullec Gregory
Publication year - 2020
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1002/alz.040375
Subject(s) - meta analysis , observational study , social class , psychology , gerontology , dementia , cognition , random effects model , population , neighbourhood (mathematics) , cognitive decline , clinical psychology , medicine , demography , disease , psychiatry , sociology , mathematical analysis , mathematics , pathology , political science , law
Background Being born into a given social class still predetermines many aspects of a person’s cognitive biography. People of higher social class have better access to education; to prestigious creative and morally rewarding jobs; and to secure income. Hence, they have better access to two most powerful dementia‐protective factors: life‐long cognitive stimulation and lower level of stress. In this work, we synthetize the association between social class and cognitive health outcomes. Method Systematic review and meta‐analysis were conducted. Inclusion criteria were community‐dwelling people age 65 and older; social class as an exposure; dementia, Alzheimer’s disease or cognitive impairment as outcomes; longitudinal observational study as the study design. MEDLINE and Psychinfo databases were used between 01/01/1979 and 07/04/2019. In selected studies, fixed and random effects and homogeneity of effects were calculated. Sensitivity analyses, subgroup analyses and meta‐regression were used to examine sources of heterogeneity and to find possible mediators. Result 998 abstracts were screened; 38 full‐text articles selected; 8 articles retained in analysis, 3 articles were found in references and 1 article was excluded because it described the same population/outcome. 54 dyads “exposure/outcome” were extracted. Individual (education, income, occupation) and group (neighbourhood) variables were used as indicators of social class. Regardless social class indicator, the pooled RR for dementia/cognitive impairment was 2.45 for fixed effect and 2.18 (95%CI: 2.03 to 2.34) for random effect with I 2 heterogeneity of 78%. In sub‐analysis of different social class indicators, the association was strong and homogeneous for income (pooled RR for random effect: 2.07 (95%CI: 1.83 to 2.34), I 2 : 45%, occupation (RR: 2.53 (95%CI: 2.34 to 2.86), I 2 =14%) and neighbourhoods (RR: 2.47 (95%CI: 2.33 to2.61), I 2 =0%). Although education (RR: 2.08 (95%CI: 1.82 to 2.38) had an overall significant association with the cognitive health outcomes, there was a large heterogeneity in the effect (I 2 =78%). Conclusion There is a strong and consistent association between social class and the risk of dementia/cognitive impairment in advanced age. Growing inequality in financial security, favorable workplace conditions and healthy local environments aggravate existing challenges of dementia. Our findings can give insight to policy makers targeting healthy cognitive aging in populations.