The team determined whether depression or anxiety co-occurs with ulcerative colitis (UC) or Crohn's disease (CD) more often than expected by chance.
The results of the study were reported in the October issue of the Journal of Epidemiology and Community Health.
The researchers conducted a nested case-control study, using a database of linked hospital record abstracts in Southern England.
Both depression and anxiety were found to precede UC significantly more often than would be predicted from the control population's experience.
The associations were strongest when the mental conditions were diagnosed shortly before UC. However, the association between depression and UC was also significant when depression preceded UC by 5 or more years.
Neither depression nor anxiety occurred before CD more often than expected by chance.
| Anxiety and depression was increased in the year after IBD diagnosis.
| Journal of Epidemiology and Community Health |
However, depression and anxiety were significantly more common after CD; the associations were strongest in the year after the initial record of CD.
UC was followed by anxiety, but not by depression, more often than expected by chance. The association was again strongest within one year of diagnosis with UC.
Author L. M. Kurina, of the Institute of Health Sciences, University of Oxford, said on behalf of the group, "The concentration of risk of depression or anxiety, one year or less before diagnosis with UC, suggests that the two psychiatric disorders might be a consequence of early symptoms of the as yet undiagnosed gastrointestinal condition.
"The data are also, however, compatible with the hypothesis that the psychiatric disorders could be etiological factors in some patients with UC."
"Most of the excess anxiety or depression diagnosed subsequent to diagnosis of IBD occurs during the year after IBD is diagnosed.
"The probable explanation is that the mental disorders are sequelae of IBD," it was concluded.