Education, wealth, and job type shape aging brains and cognitive health

New findings show how education, wealth and career paths can slow cognitive decline, promoting longer healthy years and shorter disabled states in older adults.

Study: Socioeconomic inequalities associated with the transition to neurocognitive disorders and mortality. Image credits: Shutterstock AI

This is evident from a recent study published in the journal Scientific reportsresearchers investigated the role of various indicators of socio-economic position (SEP) in the transition between cognitive states and mortality. Often measured by wealth, income, education and occupation, SEP is recognized as an important determinant of dementia risk.

The study further highlights that SEP indicators influence both the risk of cognitive decline and the potential for return from cognitive impairment to a healthier state. Some reports indicate that people from lower socio-economic backgrounds spend a greater proportion of their later years with cognitive impairment than those from higher socio-economic backgrounds.

Although previous research has shown an association, the role of socioeconomic inequalities in the transition from a healthy cognitive state to mild cognitive impairment (MCI) or dementia remains partly unclear.

About the study

In the current study, researchers examined associations of specific socioeconomic markers with the transition between cognitive states and mortality. They used data from rounds 4 (2008-09) to 9 (2018-19) of the ongoing English Longitudinal Study of Aging. Cognitive status groups were derived: no cognitive impairment (NOCI), dementia and cognitive impairment no dementia (CIND). The CIND group included MCI subjects and people with other (non-dementia) forms of cognitive impairment.

SEP was measured using three indicators: highest occupational level, household wealth excluding pensions, and education. Covariates included gender, age, and marital status. Researchers collected information on socioeconomic indicators and covariates at study baseline (Wave 4) and tracked cognitive transitions over the next ten years.

The researchers used a continuous-time Markov model to estimate the transition probabilities between cognitive states (dementia, NOCI, and CIND), while adjusting for age and gender in most cases.

A state was classified as transitory if it could continue in transition to another; otherwise it was considered an absorbent state. Death was considered an absorbent state. A total of seven transitions were possible: 1) NOCI to CIND, 2) NOCI to dementia, 3) NOCI to death, 4) CIND to dementia, 5) CIND to NOCI (reversion), 6) CIND to death, and 7) dementia until death.

Risk ratios were used for each transition type to understand how each socio-economic indicator correlates with transition risks. The time spent in each state and the chances of entering each state were also calculated. In addition, length of stay, or expected length of stay in each state, and average length of stay across states were estimated. With the exception of transitions from CIND to dementia and NOCI to dementia, the models included age, sex, and marital status covariates.

Findings

The study analyzed a cohort of 8,442 participants, on average about 67 years old. Most participants were female (55.7%) and married (65.3%). Specifically, there were 3,898 transitions from NOCI to CIND, 3,361 from CIND to NOCI, 25 NOCI to dementia, and 336 transitions from CIND to dementia. Furthermore, 295 NOCI-to-death, 192 dementia-to-death, and 1,231 CIND-to-death transitions occurred.

The transition probability from NOCI to dementia or death was remarkably low. In contrast, the transition from dementia to death was relatively high, with a probability of 21%. Higher education was associated with lower transition probabilities from NOCI to CIND and dementia. Participants with higher education were more likely to return from CIND to NOCI.

Furthermore, higher education was inversely related to the likelihood of transitioning from dementia to death; subjects with lower education had a higher mortality risk. Participants in the lowest wealth tertile had lower NOCI-to-CIND transition probability; the highest wealth tertile was more likely to experience the reverse transition from CIND to NOCI. Increasing age was associated with an increased likelihood of transitions, except for the reverse transition.

Furthermore, individuals in higher-level, professional, or managerial occupations had the lowest odds of transitioning to dementia or CIND. In contrast, more disadvantaged occupations increased the probability of transition to dementia, while more advantaged occupations increased the probability of a reverse transition. Manual/routine work increased the risk of transition to dementia or death compared to managerial/professional occupations.

The highest level of education was associated with reductions of 43%, 69%, and 39% in the risk of transitions from NOCI to CIND, CIND to dementia, and dementia to death, respectively, compared with the lowest level of education. level. Furthermore, more advantaged occupations were associated with a reduced risk of transition from NOCI to CIND. Higher wealth was associated with a greater likelihood of returning from CIND to NOCI.

Socioeconomic indicators were not associated with the transition from NOCI to dementia. People with a college education consistently spent more time in the NOCI state at a given age than people with less education. People who were professionally qualified, wealthy and well-educated at age 80 had a shorter time remaining in dementia or CIND states. Socioeconomically advantaged people had longer durations of residence in the NOCI state and shorter durations in dementia and CIND states.

Conclusions

In summary, this study shows that a significant proportion of older adults switched between cognitive states during the study period. Wealthy, highly educated and professionally qualified individuals had reduced the risks of transition to CIND and dementia.

Furthermore, socioeconomically advantaged participants showed greater odds of recurrence from CIND to NOCI; they spent less time in impaired cognitive states and more time in healthy states than disadvantaged groups. This study highlights the role of socioeconomic disparities in cognitive health and suggests that socioeconomically advantaged individuals may have protective benefits that slow or reduce cognitive decline.