Background: In recent years it has become clear that depression is a recurrent disorder, with the risk of recurrence in those with two or more episodes being as high as 90%. This has prompted interest in the consistency of individual depressive symptoms across consecutive episodes, an issue that is important for symptoms such as suicidal ideation, where a past history may give important indicators of future behaviour.
Methods: We prospectively examined 69 individuals with a history of Major Depression, over 12 months, 38 of whom experienced a recurrence of major depression during the follow-up period.
Results: Spearman's rank order correlations between severity ratings of each symptom of major depression during a previous episode and severity ratings at recurrence showed significant associations for suicidality, guilt or worthlessness and thinking difficulties only. Weighted kappa coefficients indicated relatively low levels of agreement across episodes for most diagnostic symptoms, with suicidality showing the strongest relationship. Using a broad definition of suicidality-- any reporting of thoughts of death or suicide during episode-- a much higher level of agreement (kappa = .64) was found, with 83% of individuals falling into the same category (suicidal/non-suicidal) at both episodes.
Limitations: This study was based on a relatively small sample and examines re-emergence of suicidal ideation in the absence of suicidal behaviour.
Conclusions: This study provides preliminary evidence of cross-episode consistency in the recurrence of suicidal ideation, in line with the differential activation theory of suicidality in depression.