Alzheimer Centre Limburg, School for Mental Health and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands.
CoRPS -Center of Research on Psychological and Somatic Disorders, Department of Medical and Clinical Psychology>, Tilburg School of Social and Behavioural Sciences, Tilburg University, Tilburg, The Netherlands.
J Alzheimers Dis. 2021;80(4):1675-1685. doi: 10.3233/JAD-200783.
Reductions in memory practice effects have gained interest as risk factor for future cognitive decline. Practice effects vary with age and can be moderated by factors such as individual variability in arousal or stress experience acting as an additional cognitive load.
In the current pilot study, we examined whether sympathetic nervous system activation moderates the relationship between age and practice effects.
Thirty cognitively healthy individuals aged 40-70 years performed a mnemonic discrimination task twice. Salivary alpha amylase (sAA) samples were obtained at different time points as a proxy of sympathetic activity. Spearman correlations examined the relation between practice effects and sAA. Subsequently, age by sAA interactions on practice scores were explored with bootstrapped linear regression models. Additionally, participants were divided in learners (exhibiting practice effects) and non-learners based on the difference in mnemonic discrimination performance.
Higher age and baseline SNS activity were independently related to lower practice effects. The non-learners showed significantly higher sAA scores at all time points compared to learners. Among the learners, baseline-adjusted lower levels of sAA after encoding were associated with greater practice effects, particularly in middle-aged individuals. No such interaction was observed for non-learners.
These results show that higher baseline sympathetic activation is associated with worse practice effects independently of age. Additionally, in a subgroup of middle-aged learners practice effects were observed when sympathetic activity remained low during learning. These findings suggest that elevated sympathetic nervous system activation may be a promising indicator of imminent cognitive decline.
记忆练习效应的减少作为未来认知能力下降的风险因素引起了关注。练习效应随年龄而变化，并且可以通过个体在唤醒或应激体验方面的变异性等因素来调节，这些因素作为额外的认知负荷起作用。
在当前的初步研究中，我们研究了交感神经系统的激活是否调节了年龄与练习效应之间的关系。
30 名认知健康的 40-70 岁个体两次执行记忆辨别任务。唾液α-淀粉酶 (sAA) 样本在不同时间点获得，作为交感活动的替代指标。Spearman 相关性检验了练习效应与 sAA 之间的关系。随后，采用 bootstrap 线性回归模型探讨了年龄与 sAA 的交互作用对练习得分的影响。此外，根据记忆辨别表现的差异，将参与者分为学习者（表现出练习效应）和非学习者。
较高的年龄和基线 SNS 活动与较低的练习效应独立相关。与学习者相比，非学习者在所有时间点的 sAA 分数明显更高。在学习者中，与基线相比，编码后 sAA 水平较低与更大的练习效应相关，尤其是在中年个体中。对于非学习者，没有观察到这种交互作用。
这些结果表明，较高的基线交感激活与年龄无关，与较差的练习效应独立相关。此外，在中年学习者的亚组中，当学习期间交感活动保持较低时，观察到了练习效应。这些发现表明，交感神经系统的升高可能是认知能力下降的一个有前途的指标。
