Chronic Post-Concussion Neurocognitive Deficits. II. Relationship with Persistent Symptoms

Abstract

Individuals who sustain a concussion may continue to experience problems long after their injury. However, it has been postulated in the literature that the relationship between a concussive injury and persistent complaints attributed to it is mediated largely by the development of symptoms associated with posttraumatic stress disorder (PTSD) and depression. We sought to characterize cognitive deficits of adult patients who had persistent symptoms after a concussion and determine whether the original injury retains associations with these deficits after accounting for the developed symptoms that overlap with PTSD and depression. We compared the results of neurocognitive testing from 33 patients of both genders aged 18–55 at 3 months to 5 years post-injury with those from 140 control subjects. Statistical comparisons revealed that patients generally produced accurate responses on reaction time-based tests, but with reduced efficiency. On visual tracking, patients increased gaze position error variability following an attention demanding task, an effect that may reflect greater fatigability. When neurocognitive performance was examined in the context of demographic- and symptom-related variables, the original injury retained associations with reduced performance at a statistically significant level. For some patients, reduced cognitive efficiency and fatigability may represent key elements of interference when interacting with the environment, leading to varied paths of recovery after a concussion. Poor recovery may be better understood when these deficits are taken into consideration.

The Measurement of Eye Movements in Mild Traumatic Brain Injury: A Structured Review of an Emerging Area

“…• Smooth pursuit radial and tangential error variability correlated with frontal white matter track integrity and cognitive function in mTBI and controls • Gaze error variability correlated with attention and working memory measures Maruta et al (2016) Characterize cognitive deficits of adult patients who had persistent symptoms after a mTBI and determine whether the original injury retains associations with these deficits after accounting for the developed symptoms that overlap with post-traumatic stress disorder and depression…”

“…There is currently no "gold standard" instrument for eyemovement measurement, which is likely the reason for the numerous different instruments used in the reviewed studies. The majority of studies used static infra-red eye-tracking devices in constrained seated activities (e.g., chin rest in place in front of a computer screen), but several studies did show progression to unconstrained dynamic eye-tracking protocols (Maruta et al, 2010b(Maruta et al, , 2016Stuart et al, 2019b). High resolution (>100 Hz) mobile eye-tracking during functional activities (e.g., walking or standing) may provide deeper understanding of the impact that subtle eye-movement deficits may have on those with mTBI.…”

Feasibility of using normobaric hypoxic stress in mTBI research

“…In terms of Satz's BRC model, our recently published work [61] and that of others [64,69,82,83,85] provide further support for the notion that in the presence of mTBI, stress reduces BRC below the FIT threshold, so that otherwise unmeasurable deficits become apparent. NH may be particularly useful as a stress paradigm for mTBI assessment for several reasons.…”

“…Although the immediate, acute symptoms of mTBI are well recognized, neurocognitive and neuropsychological difficulties attributable to mTBI within the postacute phase have not been as readily characterized [62][63][64] despite consistent reporting of symptoms [7,8,65,66]. This may be due to the lack of identifiable abnormalities on standard neurological imaging [66][67][68][69][70] and/or the potential for both psychological and physiological etiologies of subjective symptoms [62][63][64][65][66]71,72].…”

“…This observation suggests that individuals with mTBI history adopt a strategy of decreased speed in order to maintain preinjury levels of accuracy [75]. Similarly, Maruta et al also found that mTBI individuals were able to maintain accuracy on reaction time-based neurocognitive tasks, but at the expense of reduced efficiency and increased fatigue [64].…”