We investigate long-term cognitive effects of a hypothetical intervention, where systolic blood pressure (sBP) is monitored at more optimal levels, in a large representative sample. A limitation with previous research on the potential risk reduction of such interventions is that they do not properly account for the reduction of mortality rates. Hence, one can only speculate whether the effect is a result from changes in cognition or changes in mortality. As such, we extend previous research by providing both an etiological and a prognostic effect estimate. To do this we also propose a Bayesian semi-parametric estimation approach for an incremental intervention, using the extended G-formula. We also introduce a novel sparsity-inducing Dirichlet hyperprior for longitudinal data, demonstrate the usefulness of our approach in simulations, and compare the performance relative to other Bayesian decision tree ensemble approaches. The results revealed a weak (non-significant) prognostic effect and a significant etiological effect in later-life, but not in mid-life. These findings provide important information about long-term sBP control in cognitive aging, indicating that sBP interventions may have an effect on memory later in life at the individual level, although only small effects would be seen at the population level due to altered mortality rates.

翻译：我们在大规模代表性样本中，研究了一种假设性干预（将收缩压维持在更优水平）对认知能力的长期影响。既往关于此类干预潜在风险降低效果的研究存在局限性，即未能恰当考虑死亡率下降的影响。因此，只能推测其效果源于认知变化抑或死亡率变化。为此，我们通过提供病因学与预后两类效应估计值来拓展既往研究。我们提出了一种基于扩展G公式的贝叶斯半参数估计方法，用以评估渐进式干预效果，并首次引入一种适用于纵向数据的稀疏诱导狄利克雷超先验。通过模拟实验验证了该方法的有效性，并与其他贝叶斯决策树集成方法进行了性能比较。结果显示：在生命后期存在弱（非显著）预后效应与显著病因学效应，但在中年阶段未发现显著效应。这些发现为认知衰老过程中长期收缩压控制提供了重要依据，表明个体层面收缩压干预可能对晚年记忆产生影响，但由于死亡率改变，群体层面的效应较为微弱。