Autobiographical memory and episodic future thinking after moderate to severe traumatic brain injury

Converging evidence suggests that autobiographical memory and episodic future thinking share a common neurocognitive basis. Although previous research has shown that traumatic brain injury (TBI) can impair the ability to remember the personal past, episodic future thinking has not previously been systematically examined within this population. In this study, we examined the ability to remember events in the personal past and the ability to imagine possible events in the personal future in a sample of moderate-to-severe TBI patients. We present data on nine patients and nine healthy controls, who were asked to report a series of events that had happened to them in the past and a series of events that might happen to them in the future. Transcriptions were scored according to a reliable system for categorizing internal (episodic) and external (semantic) information. For each event described, participants also completed two modified Autobiographical Memory Questionnaire items to assess self-reported phenomenal qualities associated with remembering and imagining. In addition, TBI patients underwent neuropsychological assessment. Results revealed that TBI patients recalled/imagined proportionally fewer episodic event-specific details for both past and future events compared to healthy controls (η²(p) = 0.78). In contrast, there were no group differences in ratings of phenomenal characteristics. These results are discussed in relation to theories suggesting that remembering and imagining the future are the expression of the same underlying neurocognitive system.