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Depression and Quality of Life Mediating the Association Between Attention Deficit/Hyperactivity Disorder and Suicidality in Military Recruits.

INTRODUCTION
Military suicide remains a significant concern in many countries. Most psychological autopsy studies in this field focused on certain psychological comorbidities with suicide, namely depression, quality of life, sporadically in different populations. However, much less attention has been paid to Attention Deficit/Hyperactivity Disorder (ADHD), which is among the most common neuropsychiatric conditions in youth. This study aimed to test the associations between childhood ADHD symptoms and several suicidal behaviors, namely suicidal ideation, self-harm behaviors, and suicidal attempts. We, then, tested whether these associations would be mediated by the level of current depression and quality of life in military recruits.


MATERIALS AND METHODS
A total of 1,047 military recruits (all male, aged 20-34 years) participated in this questionnaire survey. The participants completed the Swanson, Nolan, and Pelham, Version IV Scale-Chinese version for ADHD symptoms before 12 years old; the Beck Depression Inventory, 2nd edition, for depressive symptoms and quality of life for the past 6 months; the Adult ADHD Quality-of-Life Scale; and the questions about current self-harm/suicidal behaviors on the Adult Self-Report Scale Inventory-4-Chinese version. Mediation analyses with bootstrapping of total indirect effects were used for statistical analyses.


RESULTS
Our Results revealed significant associations between recalled childhood ADHD symptoms/diagnosis (age 6-12 years) and all the three current suicidal behaviors (suicidal ideation, self-harm behaviors, and suicidal attempts; all p values <0.001). Mediation analyses revealed that all these relationships were significantly and partially mediated by depression (all p values <0.05) and quality of life (p value <0.05, but not for suicidal attempts).


CONCLUSION
The major findings of this study include that the ADHD-suicidality association is partially explained by the mediating effects of depression and quality of life, and that recalled ADHD symptoms had a stronger association with suicide attempt than with suicidal ideation in military recruits. Moreover, our finding of the highest direct effect of ADHD and lowest indirect effects of depression and quality of life on self-harm behavior indicates different associated patterns between deliberate self-harm and suicidal ideation and attempts. Our findings concord Nock's suggestion that different prevention strategies for suicidal ideation, self-harm behaviors, and suicidal attempts are warranted because of distinct courses and underlying psychopathology. This study is limited by a lack of psychiatric interview to make the diagnosis of ADHD and other psychiatric disorders, and only recruiting young men without female participants leading the generalization of our results to young women is questionable. Moreover, the lack of temporal data in this study prohibits us extend our findings to establish causality. The findings imply that assessment and intervention of depression and poor quality of life may help offset suicidal behaviors among military recruits with ADHD symptoms and/or diagnosis. Further investigations about interactions among those factors are warranted.