Episodic memory impairment in patients with repetitive head injury: Initial findings of the SNAP-CTE cohort study

Abstract

AbstractBackgroundTraumatic encephalopathy syndrome (TES) is considered a long-term, neurodegenerative consequence of repetitive head injury (RHI). This cohort study aimed to characterise the episodic memory profiles (specifically, immediate and delayed memory) of individuals with RHI history through neuropsychological assessment. Hypotheses included participants demonstrating reduced episodic memory functioning, and greater reductions in functioning observed with greater years of RHI exposure.MethodsNeuropsychological assessment was conducted on 34 adults with ≥10 years of RHI exposure as a cohort study. Main outcome measures were auditory memory indices (AMI), immediate memory indices (AII), and auditory delayed memory indices (ADI). Other potential predictors of outcome variables (in addition to years of exposure duration) were also measured and factored into analysis so that they could be controlled for.ResultsAMI [t (33) = -2.4, p = .020), AII (t = -2.7, p = .012), and ADI (t = -2.7, p = .44) were all significantly below normative levels. AMI [t (33) = 4.1, p <.001), AII (t = 4.3, p <.001), and ADI (t = 3.7, p <.001) were also significantly below participants’ measured premorbid functioning. None of the comorbidities that were considered as possible confounding variables predicted the relationship of any outcome variables.ConclusionsPrevious research (1) indicated that immediate episodic memory (i.e., encoding) impairments do not appear to be associated with RHI, and our study provides evidence to the contrary. However, further research is required on larger sample sizes to further understand the relationship between RHI and encoding deficits in this complex population.What is already known on this topic?Chronic Traumatic Encephalopathy (CTE) identified at autopsy, has been loosely associated with a history of repetitive head injury (RHI) sustained in life, yet factors that account for symptoms such as defined in life as Traumatic Encephalopathy Syndrome (TES) which can include abnormal cognitive function, behavioural dysregulation and mood disturbances in this patient cohort are yet to be comprehensively investigated.What this study adds?This research is beneficial to the scientific community mainly because it contributes to the pre-existing body of literature on the neuropsychological profile of RHI. Previous research (1) has indicated that immediate episodic memory (i.e., encoding) impairments do not appear to be associated with RHI, and our study provides evidence to the contrary.How might this study affect research, practice, or policy?This research represents progress towards further discerning a neuropsychological profile of TES, thereby potentially aiding a better clinical diagnostic presentation of the disease, which can build on potential earlier diagnosis, prevention strategies and treatment pathways.