© 2006 The Royal College of Psychiatrists
Correspondence |
Post-partum depression
Departments of Psychiatry, National Institute of Mental Health and Neurosciences, Bangalore 560029, India. E-mail: chandra{at}nimhans.kar.nic.in
Department of Clinical Psychology, National Institute of Mental Health and Neurosciences, Bangalore, India
We would like to raise some concerns about the paper by Evans et al (2005), 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 (Patel et al, 2002; Dennis & 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 (Weissman, 1979), or the Crandell Cognitions Inventory (Crandell & 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.
EDITED BY KIRIAKOS XENITIDIS and COLIN CAMPBELL
REFERENCES
- Crandell, C. J. & Chambless, D. L. (1986) The validation of an inventory for measuring depressive thoughts: the Crandell Cognitions Inventory. Behaviour Research and Therapy, 24, 403 -411.[Medline]
- Dennis, C. L. & Boyce, P. (2004) Further psychometric testing of a brief personality scale to measure vulnerability to post partum depression. Journal of Psychosomatic Obstetrics and Gynecology, 25, 305 -311.[CrossRef]
- Evans, J., Heron, J., Lewis, G., et al
(2005) Negative self-schemas and the onset of depression in
women: longitudinal study. British Journal of
Psychiatry, 186, 302
-307.
[Abstract/Free Full Text] - Patel, V., Rodrigues, M. & DeSouza, N.
(2002) Gender, poverty, and postnatal depression: a study of
mothers in Goa, India. American Journal of Psychiatry,
159, 43-47.
[Abstract/Free Full Text] - Weissman, A. (1979) The Dysfunctional Attitude Scale: a validation study. Dissertation Abstracts International, 40, 1389 -1390.
Authors' reply:
Division of Psychiatry, University of Bristol, Cotham House, Cotham Hill, Bristol BS6 6JL, UK. E-mail: j.evans{at}bristol.ac.uk
Unit of Paediatric and Perinatal Epidemiology, Division of Child Health, University of Bristol
Division of Psychiatry, University of Bristol
Unit of Paediatric and Perinatal Epidemiology, Division of Child Health, University of Bristol
EDITED BY KIRIAKOS XENITIDIS and COLIN CAMPBELL
Drs Chandra and Sudhir appear to have misunderstood the aim of our paper. The paper is not primarily about post-partum depression. We did not aim to study the overall aetiology of post-partum depression nor did we aim to accurately predict post-partum depression from the negative self-schema measure. We did aim to test an important aspect of the cognitive theory of depression, namely whether a measure of negative self-schema is associated with the onset of depression. We found there was an association and that it was equally strong whether the onset was during pregnancy, in the post-partum period or 3 years later. In the main analysis we adjusted for the psychological and socio-economic variables outlined in Table 3.
We agree, as stated in our discussion, that a more detailed questionnaire such as the Dysfunctional Attitude Scale would have provided a more comprehensive measure of self-schema. Furthermore, repeated measures would have allowed comparison with other studies and a test of the stability of these ‘schemas’. It is possible that schemas change with an experience such as motherhood, although theoretically they should be relatively stable. As these were secondary data analyses of an existing data-set, we were limited to the data available to us and these did not include any more-detailed or repeated measures of schemas.
There are clearly multiple factors that influence the onset of depression. The correspondents ask why some women have earlier onset than others. This may well be related to changing support or adverse events, but it was not the aim of our paper to address this question. Rather than speculate, the ALSPAC data-set provides an opportunity to answer this question and many others by undertaking further detailed analyses of those data.
The analyses we presented in Table 4 indicate that the strength of the association between negative self-schema and onset of depression does not diminish with time, so it is unlikely that those in the highest tertiles for depression have onset which is sooner.
This work needs to be replicated in other large longitudinal studies of both non-pregnant women and men.
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