Suchergebnisse

Abstract

Background
Low socioeconomic position (SEP) has been linked to an increased risk of dementia. However, little is known about the association between SEP trajectory and regional brain volumes related to dementia.


Methods
A random sample of community-dwelling older adults (n = 428, age = 73.1 ± 5.5) living in Tokamachi City (Niigata Prefecture, Japan) without medical histories of dementia, Parkinson's disease, and depression who underwent automated assessment of brain volumes on magnetic resonance imaging and responded to a self-administered questionnaire survey in 2017. We measured SEP in childhood (household SEP at age 15), young adulthood (education), mid-adulthood (the longest occupation), and late adulthood (current wealth), and further performed group-based trajectory analysis to identify lifetime trajectory patterns on SEP. Multivariate regression models were employed to investigate the association between SEP trajectories and 4 regional brain volumes related to the development of Alzheimer's disease (ie, entorhinal cortex, hippocampus, amygdala, and the parahippocampus), the most common type of dementia.


Results
We found 3 distinct SEP trajectories (stable middle class [68%], downward [23%], and upward [9%]). Compared to those who experienced stable middle class, older adults who experienced the upward SEP mobility had significantly larger hippocampus (β: 213.2, 95% confidence interval: 14.7, 411.8). On the other hand, older adults who experienced downward SEP mobility showed no significant differences in any of the 4 brain structural volumes.


Conclusions
Our findings indicate that upward life-course SEP mobility is associated with larger volumes of hippocampus in old age. SEP trajectory may offer us a useful lens to enhance our understanding of the etiology of dementia.

Abstract

Objectives
It is well known that low educational attainment is associated with cognitive function decline in older age. Childhood book availability may help to preserve cognitive function in older adults with low education. The study objective was to examine the association between childhood book availability and cognitive function among older adults with low educational attainment, and to investigate the mediating effect of the volume of reading-related brain regions (e.g., superior temporal cortex).


Methods
A cross-sectional study of community-dwelling older Japanese adults aged 65–84 years was conducted (n = 474). Cognitive function was assessed using the Mini-Mental State Examination (MMSE). Childhood book availability was assessed using a retrospective questionnaire. Brain region volume was measured using magnetic resonance imaging. Multivariate regression modeling and structural equation modeling were used for analysis.


Results
Both high educational attainment and childhood book availability were independently associated with high MMSE score. Stratification of educational level showed that childhood book availability was positively associated with MMSE score among participants with low educational attainment (coefficient = 1.48, 95% confidence interval [CI]: 0.31 to 2.66), but not among those with moderate or high educational attainment (coefficient = −0.01, 95% CI: −1.44 to 1.42 and −1.21, 95% CI: −3.85 to 1.42, respectively). Among participants with low educational attainment, left superior temporal cortex volume mediated the association between childhood book availability and MMSE score.


Discussion
The availability of books in childhood helps to preserve cognitive function in older adults with low education via left superior temporal cortex volume. Further research is needed to replicate these findings.