Prospective memory functions in traumatic brain injury: The role of neuropsychological deficits, metamemory and impaired self-awareness

A large body of evidence suggests that individuals with traumatic brain injury (TBI) have significant difficulties with prospective memory (PM), the memory for future intentions. However, the processes underlying this cognitive deficit remain unclear. This study aimed to gather further evidence regarding PM functions in TBI and clarify the role of neuropsychological deficits, metamemory, and mood disorders. We used a laboratory-based clinical measure, the Virtual Week, to examine PM function in 18 patients with TBI and 18 healthy control subjects. Measures of attention, processing speed, executive functions, episodic memory, and self-report questionnaires were also administered. In line with prior literature, our findings indicate that individuals with TBI had a consistent deficit compared to controls across all PM tasks. In previous studies, TBI patients had more severe impairment on time-based tasks; nevertheless, our results show that across all participants event-based tasks were easier to perform compared to time-based only when the retrospective memory demand was high. The patients were not only impaired on the prospective component of PM but also failed to recognise the content of their task (the retrospective component). Interestingly, the TBI group did not report higher levels of everyday memory problems, anxiety and depression compared to the control group. These measures also failed to correlate with PM and recognition memory performance. This study found that besides the neuropsychological deficits, a global impairment in PM functioning is present in individuals with TBI across various task types, tasks low and high in retrospective demands, and event versus time-based.