We would like to raise some concerns about the paper by Evans et al (Reference Evans, Heron and Lewis2005), which oversimplifies the aetiology of post-partum depression. Depression in pregnancy and post-partum has been globally linked to psychosocial issues (marital problems, social support, childhood adversity) and pregnancy-related factors, all of which interact with personality (Reference Patel, Rodrigues and DeSouzaPatel et al, 2002; Reference Dennis and BoyceDennis & Boyce, 2004). For the findings of the paper to be clinically relevant, it would have been useful to study the relative roles of at least some of these mediating variables, rather than focusing on personality alone.

We also feel that using six items from an interpersonal sensitivity scale for assessing the main explanatory variable is not fully justified. The items chosen measure only some aspects of the self; more-robust measures such as the Dysfunctional Attitude Scale (Reference WeissmanWeissman, 1979), or the Crandell Cognitions Inventory (Reference Crandell and ChamblessCrandell & Chambless, 1986) could have been used to assess self-schemas.

We would also like Evans et al to speculate on why some women developed depression earlier and some later (after 3 years) despite having high negative self-schemas at baseline. Is it possible that self-schema also change with experiences such as motherhood, or that support might have mediated the later onset of depression? Also, did women in the higher tertiles for negative self-schema score develop depression earlier?

In the absence of information about important psychosocial variables and factors related to the development of schemas, it is difficult to presume that negative self-schemas are alone sufficient to predict the onset of depression. The inclusion of women who had negative self-schemas but did not develop depression, and repeat assessment of those with negative self-schemas would have also better delineated state versus trait concerns. Finally, it would have been useful to have a control group of non-pregnant women to determine whether personality as a vulnerability factor is unique to pregnancy and the post-partum period.