Causal mediation analyses focus on understanding how causes exert their effects, crucial for scientific progress.
Recent years have seen significant development in defining and identifying mediational effects in rigorous causal models.
Challenges in interpreting and identifying such effects have been addressed with important progress.
Despite advancements in causal inference, statistical methodology for non-parametric estimation has been lacking.
There are limited methods available for non-parametric estimation with multiple, continuous, or high-dimensional mediators.
A study shows that six popular non-parametric mediation analysis approaches can be derived from just two statistical estimands.
An all-purpose one-step estimation algorithm is proposed for machine learning integration in mediation studies using these six definitions.
The estimators exhibit desirable properties like sqrt{n}-convergence and asymptotic normality.
Estimating first-order correction for the one-step estimator involves handling complex density ratios on high-dimensional mediators, addressed using Riesz learning.
The methods' properties are illustrated in a simulation study and applied to real data to determine how pain management practices mediate the total effect of chronic pain disorder on opioid use disorder.