LITERATURE REVIEW: Mind Wandering and Anhedonia: A Systematic Review. EMPIRICAL PAPER: An Experience Sampling Study: Does Mind Wandering Mediate the link between Depression and Anhedonia?

Abstract

Literature Review: Background: There is increasing theoretical interest in the idea that a greater tendency for the mind to wander may reduce positive emotion experience, with specific interest in clinical conditions such as depression that are characterised by reduced pleasure experience (anhedonia). However, it is unclear to what degree these claims are empirically supported. Objective: A systematic review was conducted to examine the evidence regarding the association between mind wandering and positive emotion experience. Method: The Cochrane library, MEDLINE, PsycINFO, and Web of Knowledge databases were searched. A narrative discussion considered both the pattern of findings and the methodological approaches utilised in this literature. Results: 879 studies were identified and 21 relevant papers were fully reviewed, consisting of cross-sectional, prospective and manipulation studies. Conclusions: Fourteen out of 15 cross-sectional studies supported the claim that increased mind wandering was related to decreased pleasure experience. One prospective study indicated that mind wandering generally preceded but was not subsequent to reductions in positive mood. There were six studies that manipulated mind wandering experimentally, four of which found that inducing greater mind wandering led to reduced positive affect and two of which found null results. Overall, this literature supports the claim that greater mind wandering is related to reduced positive affect. However, very few studies examined this relationship in the context of depression and therefore it remains to be established if these findings generalise to clinical populations. Empiricial Paper: Previous research has established that greater levels of mind wandering are associated with reduced positive affect (PA) in the general population. The present study aims to examine whether this mechanism may mediate the relationship between depression and reduced PA (anhedonia). A community sample (N = 69) with differing levels of depression severity took part. Using experience sampling methodology, we measured mind wandering and PA during everyday life and when completing a few scheduled positive activities. To examine if mind wandering specifically influenced PA or emotion experience more generally, we additionally measured levels of negative affect (NA). Across both contexts, both greater mind wandering and greater depression severity were independently associated with reduced PA and increased NA. Greater depression severity was associated with increasing levels of mind wandering in everyday life, but not during scheduled positive activities. Mind wandering did not mediate the link between depression and reduced PA/increased NA. Exploratory analyses did however reveal that a greater tendency for the mind wander to negative rather than positive themes did mediate the link between depression and reduced PA in everyday life. We replicated previous findings that increased mind wandering is related to reduced PA and increased NA but there was no evidence that this mediated the relationship between depression and altered affective experience. However, the greater tendency for the mind to wander to negative themes may mediate the link between depression and affect. If depression treatment approaches are to target mind wandering this suggests they should therefore focus on mind wandering valence in addition to extent.