Department of Public Health, University of Copenhagen, Copenhagen, Denmark.
Danish Aging Research Center, Institute of Public Health, University of Southern Denmark, Odense, Denmark.
PLoS One. 2021 Aug 2;16(8):e0255449. doi: 10.1371/journal.pone.0255449. eCollection 2021.
The potential association between level of education and age-related cognitive decline remains an open question, partly because of a lack of studies including large subsamples with low education and follow-up intervals covering a substantial part of the adult lifespan.
To examine cognitive decline assessed by a comprehensive clinical test of intelligence over a 35-year period of follow-up from ages 50 to 85 and to analyze the effect of education on trajectories of cognitive decline, including the effects of selective attrition.
A longitudinal cohort study with a 35-year follow-up of community dwelling members of the Glostrup 1914 cohort. The study sample comprised 697 men and women at the 50-year baseline assessment and additional participants recruited at later follow-ups. Verbal, Performance, and Full Scale IQs were assessed using the Wechsler Adult Intelligence Scale at ages 50, 60, 70, 80, and 85. To be able to track cognitive changes between successive WAIS assessments, all IQs were based on the Danish 50-year norms. Information on school education was self-reported. The association between education and cognitive decline over time was examined in growth curve models. Selective attrition was investigated in subsamples of participants who dropped out at early or later follow-ups.
The trajectories for Verbal, Performance, and Full Scale IQ showed higher initial cognitive performance, but also revealed steeper decline among participants with a formal school exam compared to participants without a formal exam. Verbal IQ showed the largest difference in level between the two educational groups, whereas the interaction between education and age was stronger for Performance IQ than for Verbal IQ. In spite of the difference in trajectories, higher mean IQ was observed among participants with a formal school exam compared to those without across all ages, including the 85-year follow-up. Further analyses revealed that early dropout was associated with steeper decline, but that this effect was unrelated to education.
Comprehensive cognitive assessment over a 35-year period suggests that higher education is associated with steeper decline in IQ, but also higher mean IQ at all follow-ups. These findings are unlikely to reflect regression towards the mean, other characteristics of the employed test battery or associations between educational level and study dropout.
教育程度与年龄相关认知衰退之间的潜在关联仍是一个悬而未决的问题，部分原因是缺乏包括大量低教育程度样本和随访间隔涵盖成人寿命大部分时间的研究。
在从 50 岁到 85 岁的 35 年随访期间，通过全面的智力临床测试评估认知衰退，并分析教育对认知衰退轨迹的影响，包括选择性淘汰的影响。
这是一项纵向队列研究，对格洛斯楚普 1914 队列的社区居民进行了 35 年的随访。研究样本包括基线评估时的 697 名男性和女性，以及后来的随访中招募的额外参与者。50 岁、60 岁、70 岁、80 岁和 85 岁时使用韦氏成人智力量表评估言语、操作和全量表智商。为了能够在连续的 WAIS 评估之间跟踪认知变化，所有智商均基于丹麦 50 岁的标准。学校教育信息由参与者自行报告。使用生长曲线模型检查教育与随时间的认知衰退之间的关联。在早期或后期随访中退出的参与者的子样本中调查选择性淘汰。
言语、操作和全量表智商的轨迹显示出较高的初始认知表现，但与没有正式考试的参与者相比，有正式学校考试的参与者的下降更为陡峭。言语智商在两个教育群体之间的差异最大，而教育与年龄之间的交互作用对于操作智商而言比言语智商更强。尽管轨迹存在差异，但在所有年龄段（包括 85 岁的随访），有正式学校考试的参与者的平均智商均高于没有正式考试的参与者。进一步的分析表明，早期辍学与更陡峭的下降相关，但这种影响与教育无关。
在 35 年期间进行全面的认知评估表明，较高的教育程度与智商的下降更为陡峭相关，但在所有随访中也与更高的平均智商相关。这些发现不太可能反映回归均值、所使用的测试电池的其他特征或教育程度与研究辍学之间的关联。
