Conditioning on a collider may or may not explain the relationship between lower neuroticism and premature mortality in Gale et al. (2017): A reply to Richardson, Davey Smith, and Munafó (2018)

In their Commentary, Richardson, Davey Smith, and Munafó (2018) note that our findings of a health-protective effect of neuroticism could be due to our conditioning on a collider (self-rated health). They conducted exploratory analyses on 18 covariates and found evidence in support of this interpretation. However, in our paper and this Reply, we carried out analyses that suggested that the health-protective effects of neuroticism were attributable to a neuroticism facet related to worry and vulnerability These analyses did not condition upon self-rated health or other possible colliders. As such, our results suggest that self-rated health may have been a suppressor variable. This interpretation is consistent with previous findings. Future studies will reveal whether self-rated health is a collider, a suppressor, or both. Until then, however, these results and those of our earlier study recommend an in-depth study of the mortality and neuroticism at the level of facets.