Adolescents in both studies who reported suicidal behavior were more than 10 times more likely than were those who did not report suicidal behavior to say that they had also experienced hallucinations or delusions, the investigators said (Arch. Gen. Psychiatry Oct. 29 [doi:10.1001/archgenpsychiatry.2012.164]).
"Strikingly, a majority of adolescents with suicidal plans or acts reported psychotic symptoms in both the ABD study (60%) and the CT (55%), studies," they noted.
The researchers also examined the link between psychotic symptoms and suicidal behavior in the subgroup of adolescents who had a diagnosable psychiatric disorder. These included major depressive disorder, adjustment disorder with depressed mood, ADHD, oppositional defiant disorder, conduct disorder, generalized anxiety disorder, social phobia, separation anxiety disorder, and OCD.
In these high-risk subjects, those who reported experiencing hallucinations or delusions were more than five times more likely to also report suicidal behavior than were subjects who had no psychotic symptoms.
Moreover, a further analysis of the data showed that adolescents who had psychotic symptoms were more likely to show the most serious suicidal behavior (planning and attempts) than the less serious suicidal ideation.
This study was not designed to examine the reasons for this robust association between psychotic symptoms and suicidal behavior, but there are several possible mechanisms.
"The most obvious is that hallucinations may direct the individual to harm or kill themselves." However, only one subject reported hearing a voice commanding him to do so, suggesting that the content of hallucinations is not to blame, at least not in this age group.
Indirect cognitive mechanisms may play a role. "Changes in the subjective sense of self, for example, are among the earliest recognizable symptoms of psychosis, and a sense of disintegration and fragmentation of the self resulting from intrusive voices or thoughts have been linked to suicidal thinking," Dr. Kelleher and his colleagues said.
Alternatively, "Bleuler’s concept of ‘the suicidal drive’ might not be just the most severe symptom of schizophrenia but the most severe symptom of a much broader psychosis phenotype made up of individuals in the general population who experience psychotic symptoms," they wrote.
It is also possible some common factor underlies both psychotic symptoms and suicidal behavior. For example, the symptoms may be a marker for deteriorating mental health, which in turn puts patients at high risk for suicide.
Traumatic experiences also might be an underlying factor. Adolescents who have experienced severe adverse events such as childhood physical or sexual abuse are known to be at increased risk for developing psychotic symptoms, and their psychological distress may also place them at high risk for suicidal behavior, the researchers said.
This study also could not delineate when psychotic symptoms arose in relation to suicidal behavior, because it was cross-sectional rather than longitudinal. "Further research with more temporal information will help to address this point," they added.
This study was funded by the European Community’s Seventh Framework Programme. No conflicts of interest were reported.