0961 Association of Sleep Disturbance and Depression with Effort-based Decision Making and Delay Discounting in Veterans

Abstract Introduction Insomnia symptoms are associated with negative depression treatment outcomes including longer time to recovery, greater risk of depression relapse, and treatment non-response. A theoretical model has hypothesized that insomnia influences depression by impacting reward processes central to depression (e.g., effort-based decision making and delay discounting). The present study examined the cross-sectional relationships of insomnia and depression symptoms with behavioral measures of these constructs. Methods Eighty-nine veterans (Mage = 47.3, 60.2% male) with a range of insomnia and depression symptoms were administered the Hamilton Rating Scale for Depression (HRSD), the Insomnia Severity Index (ISI), and one week of sleep diaries and wrist actigraphy. Participants then completed a delay discounting task (DDT) along with two measures of effort-based decision making: the Effort Expenditure for Rewards Task (EEfRT) and the Progressive Ratio Task (PRT). Nine models were analyzed: linear regressions examined associations of insomnia (ISI and sleep efficiency from diaries and actigraphy) and depression jointly, with PRT and DDT outcomes; generalized estimating equations were conducted for EEfRT outcomes. Results Higher insomnia scores predicted greater delay discounting (B = 0.065, p = .02) while depression scores did not. Diary and actigraphy-measured sleep efficiency did not significantly predict delay discounting, however greater depression symptoms predicted greater delay discounting in those models (p’s <.006). Higher insomnia scores predicted greater effort on the PRT (B = 0.027, p = .01) whereas lower depression scores predicted greater effort (B = -.039, p <.001). Sleep diary efficiency and depression were likewise significant (p = .047 and .011 respectively) but only depression was significant in actigraphy models. Neither depression nor insomnia significantly predicted EEfRT outcomes. Conclusion Although greater depression symptoms were associated with diminished effort on the PRT task and reduced willingness to wait for rewards, insomnia symptoms showed differential relationships to these processes. Insomnia symptoms may represent heightened arousal that, even in the context of depression symptoms, may contribute to difficulty with disengagement in certain reward-relevant tasks. Future research is needed to disentangle the relative contributions of insomnia and depression to reward-relevant behavior. Support (if any) This study was supported by the Department of Veterans Affairs, CSR&D (Boland, IK2 CX001501).