Influence of Head Injury on Episodic Memory, Meta-memory, and Cannabis Use

Abstract

Mild head injuries (MHI) are implicated in impairments of various cognitive constructs, including memory. Specifically, episodic memory performance is shown to be dampened post-MHI. Further, head injuries are also associated with problems in processing and reacting to emotional stimuli and, overall, research has shown that those with head injuries are less able to recall emotional stimuli compared to their No-MHI cohort. This literature is lacking in detailed measures of narrative episodic memory, especially in those with milder versus moderate or severe head injuries. Most studies implement word-list tasks to assess episodic memory, so the aim of the present study was to assess episodic memory using a story task, which is more reflective of memory usage required in day-to-day tasks. The goal of this research was to examine emotionally-valenced narrative recall in persons with MHI, while accounting for possible emotion effects. Subjective-memory, or meta-memory, was also of interest. As head injuries are whole-brain events, various neurological structures can be impacted, but in particular, involvement of the prefrontal cortex (PFC) has been acknowledged. Even minor disruption to the PFC is associated with impulse control and sensation-seeking behaviours, including substance use. Those with a history of MHI have been shown to be more vulnerable to substance use/abuse. Given the recent legalisation of cannabis in Canada and its increased medical and recreational use, in addition to its influence on memory and cognitive, this research also investigates the nature, and interaction, of cannabis consumption in relation to MHI. This study recruited 134 Brock University students to assess the relationships between MHI and episodic memory, subjective memory, emotional processing, and cannabis use. Results indicated that the MHI group performed similarly to the No-MHI group in recall capacity, and with both groups demonstrating a potent valence-related effect. Further, cannabis use was reported to a greater degree by those with an MHI, demonstrating that high-functioning university students have the facilities to overcome possible narrative episodic memory impairments attributable to a head injury, however, they remain disadvantaged in terms of substance use and are disproportionately affected by it.