Impairments in Physiological Reactivity to Emotive Stimuli After Traumatic Brain Injury: A Systematic Review of Skin Conductance and Heart Rate Variability Evidence

OBJECTIVE

To examine evidence of impairments in physiological reactivity to emotive stimuli following traumatic brain injury (TBI).

METHODS

A search of PsychINFO, CINAHL (Cumulative Index to Allied Health Literature), Web of Science, EMBASE (Excerpta Medica dataBASE), and Scopus databases was conducted from 1991 to June 24, 2021, for studies comparing changes in skin conductance or heart rate variability to emotive stimuli between adults with TBI and controls. Two reviewers independently assessed eligibility and rated methodological quality.

RESULTS

Twelve eligible studies examined physiological reactivity to laboratory-based emotive stimuli, which included nonpersonal pictures/videos, posed emotion, stressful events, and personal event recall. Overall, 9 reported evidence that individuals with TBI experience lower physiological reactivity to emotive stimuli compared with healthy controls, although the findings varied according to the type and valence of emotional stimuli and physiological parameter. Most studies using nonpersonal pictures or videos found evidence of lower physiological reactivity in TBI participants compared with controls.

CONCLUSIONS

Based on laboratory-based studies, individuals with TBI may experience lower physiological reactivity to emotive stimuli. Further research is needed to investigate physiological responses to personally relevant emotional stimuli in real-world settings and to understand the interplay between physiological reactivity, subjective experiences, and behavior.

Predictive Value of Subacute Heart Rate Variability for Determining Outcome Following Adolescent Concussion

Objective assessments of concussion recovery are crucial for facilitating effective clinical management. However, predictive tools for determining adolescent concussion outcomes are currently limited. Research suggests that heart rate variability (HRV) represents an indirect and objective marker of central and peripheral nervous system integration. Therefore, it may effectively identify underlying deficits and reliably predict the symptomology following concussion. Thus, the present study sought to evaluate the relationship between HRV and adolescent concussion outcomes. Furthermore, we sought to examine its predictive value for assessing outcomes. Fifty-five concussed adolescents (12–17 years old) recruited from a local sports medicine clinic were assessed during the initial subacute evaluation (within 15 days postinjury) and instructed to follow up for a post-acute evaluation. Self-reported clinical and depressive symptoms, neurobehavioral function, and cognitive performance were collected at each timepoint. Short-term HRV metrics via photoplethysmography were obtained under resting conditions and physiological stress. Regression analyses demonstrated significant associations between HRV metrics, clinical symptoms, neurobehavioral function, and cognitive performance at the subacute evaluation. Importantly, the analyses illustrated that subacute HRV metrics significantly predicted diminished post-acute neurobehavioral function and cognitive performance. These findings indicate that subacute HRV metrics may serve as a viable predictive biomarker for identifying underlying neurological dysfunction following concussion and predict late cognitive outcomes.