Association between social class and cognitive health outcomes in older adults: Systematic review and meta‐analysis of longitudinal studies
Bibliographic record
Abstract
Abstract 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 I2 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), I2: 45%, occupation (RR: 2.53 (95%CI: 2.34 to 2.86), I2=14%) and neighbourhoods (RR: 2.47 (95%CI: 2.33 to2.61), I2=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 (I2=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.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.013 | 0.036 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.016 | 0.030 |
| Bibliometrics | 0.007 | 0.008 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".