Alterations in nocturnal wakefulness and cognitive control are both associated with suicidal thoughts and behaviors in cross-sectional research, but given the methodological limitations of this work, the role that these alterations play in proximal suicide risk remains unclear. We propose to intensively assess veterans with insomnia and suicidal ideation recruited from a posttraumatic stress disorder (PTSD) residential unit to explore the associations among nocturnal wakefulness, cognitive control, and suicide risk. We also anticipate that the associations observed between nocturnal wakefulness, cognitive control, and suicidal ideation will not be exclusive to PTSD, but that PTSD serves as an ideal population in which to test these associations given the importance of disturbances in nocturnal wakefulness, cognitive control, and suicidal ideation among patients with the disorder.
The aims are:
Aim 1 : To evaluate associations between nocturnal wakefulness and suicide ideation prospectively, in veterans with PTSD. Hypothesis 1: Longer duration of nocturnal wakefulness, as indexed by minutes awake from 11 PM ? 7 AM based on movement on the mattress sensor strip, will be associated with higher next-day suicidal ideation, above and beyond the influence of PTSD and depression severity, baseline sleep disorder symptoms, and demographic variables (e.g., age, gender, race/ethnicity).
Aim 2 : To evaluate associations between cognitive control and suicidal ideation prospectively, in veterans with PTSD. Hypothesis 2: Reduced cognitive control (daily cognitive task performance, completed in the morning hours and when awake at night) will be associated with higher subsequent suicidal ideation, above and beyond the influence of PTSD and depression severity, baseline cognitive control performance, and demographic variables.
Aim 3 : To evaluate evidence for cognitive control as a mediator of the association between nocturnal wakefulness and suicidal ideation prospectively, in veterans with PTSD. Hypothesis 3: The association between nocturnal wakefulness and suicidal ideation will be partially mediated by reduced cognitive control performance. This R21 will support a subsequent R01 project to test an algorithm for the classification of suicidal ideation and behavior based on alterations in nocturnal wakefulness and cognitive control, utilizing methods from this proposal as well as additional levels of analysis (e.g., neural activation). We plan for the results of the proposed project to inform a new line of applied research that will directly utilize our results to develop new ecological momentary intervention strategies aimed at mitigating proximal suicide risk.
Alterations in nocturnal wakefulness and cognitive control may be important proximal risk factors for suicide, though no studies have systematically manipulated and observed the effects of these variables on suicide risk. The goal of this study is to intensively assess nocturnal wakefulness, cognitive control, and suicidal ideation in the naturalistic environment of veterans with posttraumatic stress disorder (PTSD) in a residential clinic. This study may lead to the development of strategies to improve the detection of the transition from lower- to higher- risk states among individuals with alterations in nocturnal wakefulness and cognitive control.
