Short CommunicationPatients with bipolar disorder show a selective deficit in the episodic simulation of future events
Highlights
► In this study we tested the ability of patients with bipolar disorder to imagine future life events. ► Patients were selectively impaired at imagining episodic aspects of future events. ► No differences emerged for semantic aspects of future events. ► There was no influence of emotional valence on the amount of details reported.
Introduction
Recent work has examined autobiographical recollection in patients with bipolar disorder (BD). As in patients with major depressive disorder (MDD), these studies reveal that autobiographical memory in patients with BD is characterized by overgeneralized recall comprising primarily factual or repeated information as opposed to details specific in time and in place and definitive of episodic re-experiencing (Mansell and Lam, 2004, Mowlds et al., 2010, Scott et al., 2000, Tzemou and Birchwood, 2007). More recently, workers in the field of cognitive neuroscience have begun to examine the close relation between autobiographical recollection of past events and the simulation of future events (e.g., Spreng & Levine, 2006). In addition to identifying common cognitive processes including imagination (Addis, Pan, Vu, Laiser, & Schacter, 2009) and perspective taking (D’Argembeau & Van der Linden, 2004) that are involved in recollection and in future simulation, these studies have revealed a core neural network subserving both processes (Addis et al., 2009, Spreng et al., 2009). Critically, patients with BD show structural (for a review see Konarski et al., 2008) and/or functional (for a review see Drevets, Price, & Furey, 2008) brain changes in many of the same neural regions, including the hippocampus and prefrontal cortex, implicated in this network. At present, however, it is unclear whether deficits in the autobiographical recollection of past events among patients with BD extend to the related process of simulation of future events. The primary aim of the present study was to examine the ability of patients with this disorder to engage in prospective simulation of positive, negative and neutral events. A secondary goal was to examine the relation of simulation performance to several key clinical variables, including symptom severity and illness burden, shown previously to moderate autobiographical memory (AM) performance in patients with mood disorders (for a review see King et al., 2010).
Studies examining the relation between autobiographical recollection of past events and future simulation draw heavily on Tulving, 1985, Tulving, 2002) conception of autonoetic consciousness or mental time travel as the ability to travel either backwards or forwards in time and re-experience or pre-experience an event. More recently, Schacter and Addis (2007) proposed the constructive episodic simulation hypothesis that posits that while imagining future events individuals draw on memory of past events, recombining and elaborating details of past experience to simulate possible happenings. Hence, memory is an adaptive process (Bartlett, 1932, Suddendorf and Corballis, 2007), including the ability to predict future events with a fair amount of accuracy. Critically, simulation relies most heavily upon the ability to re-experience temporally, spatially and contextually specific episodic memory details that include happenings, sensations, perceptions, thoughts and feelings (Tulving, 2001). In contrast, semantic memory involves information that is context and time independent and is thought less crucial to future simulation. Of note, episodic and semantic memory have been shown to be dissociable neuropsychologically (Eslinger, 1998, Gardiner and Java, 1991, McKinnon et al., 2006) and in development (Fivush, 2010, Mäntylä, 1993, Parkin and Walter, 1992), as well as through imaging techniques (Levine et al., 2004, Svoboda et al., 2006).
In line with the constructive episodic simulation hypothesis, evidence gathered to date suggests that the neural substrates for recollecting the past and imagining the future show substantial overlap (Addis et al., 2007, Conway et al., 2003, Hassabis et al., 2007). For example, recalling the past or imagining the future engages both bilateral frontopolar cortex (Okuda et al., 2003) implicated in self-referential processing (Gusnard, Akbudak, Shulman, & Raichle, 2001) and medial temporal lobe (MTL) areas, including the hippocampus, involved in the retrieval of past events. In a recent study, increased activation in the left posterior hippocampus was associated with more vivid event descriptions for past and for future events (Addis & Schacter, 2008). Indeed, when compared to neurologically intact controls, patients with hippocampal damage recall fewer spatial details when asked to construct future events (Hassabis, Kumaran, Vann, & Maguire, 2007). A small number of neural regions, however, appear preferentially activated during recollection of past and of future events, including posterior visual cortex and parahippocampus (Addis et al., 2009, Addis et al., 2009). In one additional study, the left anterior hippocampus was more active during simulation of future imaged events than recollection of the past (Addis & Schacter, 2008).
Many of the same neural regions and cognitive processes implicated in future episodic thinking are impacted in patients with BD. Recollective memory impairments are among the most commonly reported cognitive deficits in patients with mood disorders (MacQueen, Galway, Hay, Young, & Joffe, 2002). Although results are inconsistent, volume loss has been reported in the hippocampus of patients with BD (Blumberg et al., 2003), and may contribute to this pattern of memory impairment (Yucel et al., 2007). Regions preferentially involved in self-referential processing and perspective taking, processes recently shown to be impaired in patients with BD (Cusi et al., 2010, McKinnon et al., 2010), also show volume loss and/or changes in functional activation, including the orbitofrontal cortex (Blumberg et al., 2006), subgenual prefrontal cortex (Haznedar et al., 2005), and the anterior cingulate (Farrow, Whitford, Williams, Gomes, & Harris, 2005). Of note, the dorsolateral prefrontal cortex also shows volume loss in BD (Coffman, Bornstein, Olson, Schwarzkopf, & Nasrallah, 1990). This area is strongly associated with working memory (Arts, Jabben, Krabbendam, & van Os, 2008). Finally, spatial processing (Shestyuk & Deldin, 2010) and imagery (Williams et al., 1996), key to both episodic recollection and future simulation, have been shown to be negatively affected in patients with mood disorders. Hence, it appears likely that the presence of structural and functional brain changes in patients with BD and their putative impact on cognitive function may alter related processes, including future episodic simulation. Indeed, many of these same neural regions and cognitive processes are thought central to autobiographical recollection (King et al., 2010), known to be impacted in BD and requisite to future simulation.
Few studies, however, have examined future thinking in patients with mood disorders. In one study, dysphoric individuals predicted that they would experience more negative events in their lives and generated these events more quickly than did controls (MacLeod & Cropley, 1995). In a similar experiment involving individuals diagnosed with MDD (MacLeod, Tata, Kentish, & Jacobsen, 1997), patients were less likely to predict future positive events than were controls; this finding was subsequently replicated in individuals with mixed psychiatric diagnoses who had attempted suicide (MacLeod et al., 1993, MacLeod et al., 2005).
In another study, Williams et al. (1996) examined the ability of patients with mixed psychiatric diagnoses (including MDD; none of the patients had a diagnosis of BD) who had attempted suicide to generate future event descriptions in response to positive, negative and neutral cue words. As predicted, patients generated less specific descriptions of both future and past events than did matched controls. Despite these early investigations, to date, no study has examined the qualitative characteristics of future episodic simulation in patients with BD, including number and type of events details generated. Here, we used a modified Autobiographical Interview procedure (see Addis, Sacchetti, Ally, Budson, & Schacter, 2009) to examine future episodic simulation in BD. In line with the constructive episodic simulation hypothesis, we hypothesized that this population would show poor episodic simulation of future events, given cognitive declines in constituent processes and changes in neural regions critical to past recollection and future simulation. Furthermore, given that AM deficits in BD appear to involve an inability to recall details specific in time and in place and definitive of episodic re-experiencing, we predicted that patients would experience greater difficulty simulating episodic than non-episodic details of future happenings.
In healthy populations, recall of emotional autobiographical events has been associated with heightened recollection compared to neutral events (D’Argembeau et al., 2003, D’Argembeau and Van der Linden, 2004, Schaefer and Philippot, 2005). In patients with BD, the impact of emotion on AM is less clear. Both Scott et al. (2000) and Tzemou and Birchwood (2007) showed that, relative to matched controls, patients with BD were equally overgeneral during recollection of past positive and negative events. By contrast, Mansell and Lam (2004) found that patients with BD were more overgeneral during recollection of negative compared to positive events. In order to examine whether emotion impacts future simulation in patients with BD, participants in the present study were asked to imagine future positive, negative and neutral events. Finally, in light of recent findings suggesting a relation between cognitive impairment, structural and functional brain changes, and clinical variables such as illness severity and past course of illness (e.g., Lebowitz et al., 2001, McKinnon et al., 2009, van Gorp et al., 1998), we examined the relation between these clinical markers and future simulation performance.
Section snippets
Participants
Twenty outpatients (mean age = 45.7, SD = 10.5; 12 females; 12 bipolar I, 8 bipolar II) enrolled in the study. Patients were recruited through the Mood Disorders Clinic at St. Joseph’s Healthcare (Hamilton, Canada). The Structured Clinical Interview for DSM-IV was administered to confirm a primary diagnosis of BD, establish disease history, and rule out co-morbidity. A control group consisted of twenty subjects with no history of psychiatric illness. The control group was matched to the patients in
Results
The ANCOVA revealed that there was a two-way interaction between group and detail (F = 5.06, df = 1, 37, p < .05, ηp2 = .12) (Fig. 1). This was due to patients producing significantly fewer internal details than controls (t = 3.41, df = 38, p < .01; HC mean = 136.8, SD = 53; BD mean = 84.4, SD = 43.4); there were no differences between groups with respect to external details. Removal of patients with BD on benzodiazepines from this analysis did not alter this finding. There was no effect of valance; patients
Discussion
The primary aim of the present study was to examine for the first time future episodic simulation in patients with BD, a population that reliably demonstrates deficits in related autobiographical recollection. In line with the constructive episodic simulation hypothesis that posits future stimulation relies heavily upon recollection of details of past events, patients with BD generated significantly fewer episodic details for positive, negative and neutral future events than did matched
Acknowledgments
We are grateful to the patients and their families for assistance. We thank Katherine Herdman for scoring assistance with scoring the autobiographical memories and Cynthia Gee, Anne Politano and Kailee Fuller for transcribing the recorded interviews. We are also grateful to Helen Begin, Scott Simons, Tana Pati and Cindy D’Amico for their efforts in recruitment and patient assessment. This study was supported by National Alliance for Research on Schizophrenia and Depression (NARSAD), the
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Projecting into the future: Neuropsychology, neuroimaging, and psychopathology
2022, Annales Medico-PsychologiquesCognitive mechanisms of episodic simulation in psychiatric populations
2021, Behaviour Research and TherapyCitation Excerpt :Using tasks that assessed the specificity of future simulations (modified AMT task, SCEFT, or slightly modified tasks), patients with depression (Addis et al., 2016; Belcher & Kangas, 2014; Hach, Tippett, & Addis, 2014; Hallford, Barry, et al., 2020), suicidality (most of whom had a depression diagnosis) (Williams et al., 1996), dysphoria (see Footnote1) (Anderson, Boland, & Garner, 2016; Dickson & Bates, 2006), PTSD (Brown et al., 2013; Kleim, Graham, Fihosy, Stott, & Ehlers, 2014), schizophrenia (Chen et al., 2016; D'Argembeau, Raffard, & Van der Linden, 2008; de Oliveira et al., 2009; Raffard, Esposito, Boulenger, & Van der Linden, 2013; Wang et al., 2017), and bipolar disorder (Boulanger, Lejeune, & Blairy, 2013) described future simulations with less specificity when compared to controls. Using the adapted AI task or slightly modified tasks, patients with depression (King, Macdougall, Ferris, Herdman, & McKinnon, 2011; Parlar et al., 2016), PTSD (Brown et al., 2014), bipolar disorder (King, Williams, et al., 2011), and schizophrenia (Yang et al., 2019) provided future simulations with fewer internal details (i.e., details tied to a specific time and place) than controls. Using similar measures to the adapted AI task, patients with schizophrenia have been observed to include less time and place details (Painter & Kring, 2016) and contextual details (Malek et al., 2019) when describing the future.
Episodic specificity induction and scene construction: Evidence for an event construction account
2019, Consciousness and CognitionCitation Excerpt :Conceptually, effects of ESI on subsequent event detail within scene construction fits with emerging frameworks and data that highlight the roles of both spatial and non-spatial or event processing in generative “memory-like” tasks (e.g., Addis, 2018; Conway & Loveday, 2015; de Vito et al., 2012; Eichenbaum, 2017; Moscovitch et al., 2016; Schiller et al., 2015). Functionally, the results may also be important for understanding better the role that event construction plays in mnemonic disruptions in specific populations, such as depression and aging, characterized by overgeneralized memory and related processes (for review, see Erten & Brown, 2018; Hitchcock et al., 2017; and Hallford et al., 2018; for example empirical work, see King et al., 2011). Incorporating event construction prompts in specificity trainings like MEST may boost specificity and reduce symptoms of psychopathology further than current approaches, which could impact the efficacy of training.
Psychopathology and episodic future thinking: A systematic review and meta-analysis of specificity and episodic detail
2018, Behaviour Research and TherapyCitation Excerpt :Although some previous studies have examined the subjective sense of vividness in EFT (e.g., Holmes et al., 2011; Wu, Szpunar, Godovich, Schacter, & Hofmann, 2015) we chose to exclude these assessments as subjective ratings of vividness may be confounded by thoughts that evoke strong feelings, but might not involve many or any contextual details. Further, objective assessments of specificity and detail in EFT have been shown to be correlated with relevant clinical variables and outcomes such as apathy (Raffard, Esposito, Boulenger, & Van der Linden, 2013), dysphoria (King, MacDougall et al., 2011; King, Williams et al., 2011) and attempted suicide (Williams et al., 1996). The secondary aims of the study were to examine whether any effects differ dependent on psychiatric diagnosis, and whether the assessment methodology of EFT might also affect outcomes.
Overgenerality memory style for past and future events and emotions related in bipolar disorder. What are the links with problem solving and interpersonal relationships?
2013, Psychiatry ResearchCitation Excerpt :Further, several neuroimaging studies observe the activation of a common core brain network, in both bilateral frontopolar and medial temporal lobe areas, during the generation of past as well as future events (Addis et al., 2007; Okuda et al., 2003; Szpunar et al., 2007). Recently, King et al. (2011) investigated BDs’ capacity to imagine future events. They found that BDs generated significatively less episodic details than HCs, regardless of the valence.