Amnesia and future thinking: Exploring the role of memory in the quantity and quality of episodic future thoughts

Abstract

ObjectivesTo examine the impact of memory accessibility on episodic future thinking.DesignSingle‐case study of neurological patient HCM and an age‐matched comparison group of neurologically Healthy Controls.MethodsWe administered a full battery of tests assessing general intelligence, memory, and executive functioning. To assess autobiographical memory, the Autobiographical Memory Interview (Kopelman, Wilson, & Baddeley, 1990. The Autobiographical Memory Interview. Bury St. Edmunds, UK: Thames Valley Test Company) was administered. The Past Episodic and Future Episodic sections of Dalla Barba's Confabulation Battery (Dalla Barba, 1993, Cogn. Neuropsychol., 1, 1) and a specifically tailored Mental Time Travel Questionnaire were administered to assess future thinking in HCM and age‐matched controls.ResultsHCM presented with a deficit in forming new memories (anterograde amnesia) and recalling events from before the onset of neurological impairment (retrograde amnesia). HCM's autobiographical memory impairments are characterized by a paucity of memories from Recent Life. In comparison with controls, two features of his future thoughts are apparent: Reduced episodic future thinking and outdated content of his episodic future thoughts.ConclusionsThis article suggests neuropsychologists should look beyond popular conceptualizations of the past–future relation in amnesia via focussing on reduced future thinking. Investigating both the quantity and quality of future thoughts produced by amnesic patients may lead to developments in understanding the complex nature of future thinking disorders resulting from memory impairments.Practitioner points We highlight the clinical importance of examining the content of future thoughts in amnesic patients, rather than only its quantitative reduction. We propose an explanation of how quantitative and qualitative aspects of future thinking could be affected by amnesia. This could provide a useful approach to understand clinical cases of impaired prospection. Limitations Systematic group investigations are required to fully examine our hypothesis. Although the current study utilized typical future thinking measures, these may be limited and we highlight the need to develop clinically relevant measures of prospection.

Episodic and semantic content of memory and imagination: A multilevel analysis

“…While generally patients with episodic amnesia attributable to damage to the hippocampus and related structures are impaired at both remembering past events and imagining personal future episodes (Andelman, Hoofien, Goldberg, Aizenstein, & Neufeld, 2010; Cole, Morrison, Barak, Pauly-Takacs, & Conway, 2016; Hassabis, Kumaran, Vann, & Maguire, 2007; Klein, Loftus, & Kihlstrom, 2002; Kurczek et al, 2015; Kwan, Carson, Addis, & Rosenbaum, 2010; Race, Keane, & Verfaellie, 2011), a subset of such patients – particularly those with developmental amnesia – retain some ability to simulate future events (Cooper, Vargha-Khadem, Gadian, & Maguire, 2011; Dede, Wixted, Hopkins, & Squire, 2016; Hurley, Maguire, & Vargha-Khadem, 2011; Maguire, Vargha-Khadem, & Hassabis, 2010; Squire et al, 2010). However, when such patients generate “internal” details during future imagination, descriptions of these events seem to be fragmented and lacking in spatial coherence (Hassabis et al, 2007, though see Dede et al, 2016).…”

Episodic future thinking: mechanisms and functions

“…For example, studies that have used the AI to compare healthy older adults with young adults consistently show that older adults produce fewer internal/episodic details and more external/semantic details for both remembered past events and imagined future events, suggesting a common role of episodic memory in both event types (for review of early studies, see 16, and for recent and related evidence, see 5, 17–21). Reductions in episodic detail for both past and future events using the AI and related procedures have also been documented in various patient populations, including in recent studies of patients with depression (22), post-traumatic stress disorder (23), amnesic syndrome (24–27; but see 28 for relatively preserved future imagining in amnesics), Alzheimer’s disease (29–30), unilateral temporal lobe epilepsy (31), schizophrenia (32), prefrontal lesions (33), and long-term opiate users (34). …”

The remembering–imagining system

“…Related to the notion that recent episodic memories allow the formation of (effective or adaptive) episodic simulations (see Schacter et al, 2012a for a detailed review; Schacter and Madore, 2016), we recently had the opportunity to study future simulations in a densely amnesic patient (Cole et al, 2016). Patient HCM, a 66 year-old highly educated married man with four adult children, suffered a series of cardiovascular incidents leading to hospitalization in a rehabilitation center with 24-hour care.…”