I READ WITH interest the article by Doihara et al. that was recently published in this Journal.1 I would like to expand on the discussion of the results.
Multiple lines of evidence suggest that aggression is associated with suicidal behavior. In our study of depressed patients, for each incremental point on the Brown–Goodwin Aggression scale, the odds of being a suicide attempter increased by 10%.2 A study of adults ≥50 years showed that the association of general aggression and suicide extends to middle and older adulthood, and aggression may serve as a marker for suicide risk before the onset of depression.3 It has also been observed that the use of violent method of suicide is a behavioral marker of a higher level of lifetime impulsive–aggressive behaviors.4 Given the evidence linking low serotonergic activity separately to suicidal behavior and aggression, low serotonergic activity may underlie both conditions. Low serotonergic activity may mediate genetic and developmental effects on suicide and aggression.
I have noted that in the Doihara et al. study 20% of patients had anxiety and stress-related disorders and 36% of suicide attempters had mood disorders.1 This underlines the importance of a relationship between depression, traumatic stress, and suicidal behavior. Significant evidence suggests that traumatic events generally increase a person's suicide risk. Studies of suicidal ideation and behavior in subjects with comorbid post-traumatic stress disorder (PTSD) and major depressive episode (MDE) found that PTSD and MDE interact to increase the level of suicidal ideation and behavior, compared with that in subjects with PTSD or MDE alone.5 I have recently developed the concept of post-traumatic mood disorder (PTMD).5 I have suggested that some or all individuals diagnosed with comorbid PTSD and depression have a separate psychobiological condition that can be termed PTMD. The idea was based on the fact that a significant number of studies suggested that patients suffering from comorbid PTSD and depression differed clinically and biologically from individuals with PTSD alone or depression alone. Persons with PTMD are more impulsive–aggressive and more suicidal compared to individuals with PTSD alone or depression alone.5 Further studies of aggression, impulsivity and suicidality in psychiatric patients, especially in individuals with depressive and stress-related disorders, may produce important and interesting results.