0090 Sleep Contributes to the Negative Memory Bias in Individuals with High Depressive Symptoms

Introduction Depressed individuals typically exhibit superior memory for negative compared with neutral and positive information. During sleep, memory consolidation processes stabilize and strengthen recent memories for long-term storage. In keeping with theories suggesting that goal-consistent memories are preferentially consolidated over other memories during sleep, we hypothesized that sleep-dependent memory consolidation may contribute to this memory bias through the selective strengthening of negative memories over other memories in depressed individuals. Methods Potential participants were screened with the Beck Depression Inventory (BDI) and individuals with high depressive symptomology were invited to participate. All participants listened to a story with happy, sad, and neutral details and then took a 90-min break. During the break, half of each group (high or low depressive symptoms) took a nap monitored with polysomnography (n = 31). The other halves of each group remained awake (n= 36). After the break, all participants took a free recall test for details from the story heard before the break. Results For participants who slept during the break, there were no differences in time spent asleep, time spent in different sleep stages, slow-oscillatory power, or sleep spindle activity between high and low depressive participants. However, participants with high depressive symptoms recalled a higher proportion of sad details and a smaller proportion of happy details than participants with low depressive symptoms. For participants who remained awake during the break, there were no differences in the proportion of happy or sad details recalled between high and low groups. Conclusion A negative memory bias in individuals with high depressive symptoms was only present for participants with high depressive symptoms who slept during the break, indicating that sleep-dependent memory consolidation contributes to the negative memory bias in individuals with high depressive symptoms. Future treatments aimed at prioritizing positive and/or neutral memories for sleep-dependent memory consolidation may help to ameliorate the negative memory bias in depressed individuals. Support (if any)