Notes from the Field: Increases in Imported Malaria Cases - Three Southern U.S. Border Jurisdictions, 2023.

Malaria is a severe and potentially fatal mosquitoborne disease caused by infection with Plasmodium spp. parasites. Although malaria is no longer endemic in the United States, imported infections are reported annually; the primary risk group has been U.S. residents traveling to areas where malaria is endemic (1). In 2023, sporadic locally acquired mosquito-transmitted malaria cases were reported in several U.S. states (2,3). This report describes increases in imported malaria cases in 2023 compared with 2022 in three public health jurisdictions along the U.S. southern border.

Access to Urgent Care Practices Improves Understanding and Management of Endemic Coccidioidomycosis: Maricopa County, Arizona, 2018-2023.

BACKGROUND: Coccidioidomycosis within endemic regions is often undiagnosed because appropriate testing is not performed. A dashboard was developed to provide information about the prevalence of coccidioidomycosis throughout the year. METHODS: Banner Urgent Care Service has many clinics within Maricopa County, Arizona, a highly endemic region for coccidioidomycosis. All clinic visits and subset analyses for patients with ICD10 codes for pneumonia (J18.*) or erythema nodosum (L52) between 2018-2024 were included. Tabulated were daily frequencies of visits, pneumonia and erythema nodosum coding, coccidioidal testing, and test results. Banner Urgent Care Services' counts of monthly coccidioidomycosis diagnoses were compared to those of confirmed coccidioidomycosis cases reported to Maricopa County Department of Public Health. RESULTS: Monthly frequencies of urgent care coccidioidomycosis diagnoses strongly correlated with public health coccidioidomycosis case counts (r=0.86). Testing frequency for coccidioidomycosis correlated with overall pneumonia frequency (r=0.52). The proportion of pneumonia due to coccidioidomycosis varied between <5% and greater than 45% within and between years. Coccidioidomycosis was a common cause of erythema nodosum (65%, 95% confidence: 45%-67%) and independent of pneumonia. Over half of Banner Urgent Care Services' coccidioidomycosis diagnoses were coded for neither pneumonia nor erythema nodosum. CONCLUSION: Data provided by the coccidioidomycosis dashboard can assist urgent care practitioners in knowing when coccidioidomycosis is prevalent in the community. Patients with exposure to endemic coccidioidomycosis who develop erythema nodosum or pneumonia should routinely be tested for coccidioidomycosis. Data from private healthcare organizations can augment surveillance of diseases important to public health.

Epidemiology of musculoskeletal injury in professional and amateur golfers: a systematic review and meta-analysis.

OBJECTIVE: To determine the prevalence and incidence of musculoskeletal injury in amateur and professional golfers, and to identify common injury sites and factors associated with increased injury frequency. DESIGN: Systematic epidemiological review and meta-analysis. DATA SOURCES: PubMed (Medline), Embase, the Cochrane Library and SPORTDiscus were searched in September 2023. ELIGIBILITY CRITERIA: Studies published in the English language reporting the incidence or prevalence of musculoskeletal injuries in golfers at all anatomical sites. RESULTS: 20 studies (9221 golfers, 71.9% male, 28.1% female) were included, with mean age 46.8 years. Lifetime injury prevalence was significantly greater in professional golfers (73.5% (95% CI: 47.3% to 93.0%)) than amateur golfers (56.6% (95% CI: 47.4% to 65.5%); relative risk (RR)=1.50, p<0.001). Professional golfers had a significantly greater lifetime prevalence of hand and wrist (RR=3.33, p<0.001) and lower back injury (RR=3.05, p<0.001). Soft tissue injuries were most common, and diagnoses were typically non-specific. Injury frequency was not associated with age or sex. Two studies reported a greater injury risk in amateur golfers playing more than three and four rounds per week. CONCLUSION: Over half of golfers are at risk of sustaining a musculoskeletal injury during their lifetime. Risks and patterns of injury differ between professional and amateur golfers, with professionals significantly more likely to develop lower back, and hand and wrist injuries. A recent international consensus statement on the reporting of injury and illness in golf should aid consistency in future research assessing the epidemiology of specific diagnoses, informing golf injury prevention and management strategies. PROSPERO REGISTRATION NUMBER: CRD42023408738.

The virtual brain endocast of Trogosus (Mammalia, Tillodontia) and its relevance in understanding the extinction of archaic placental mammals.

After successfully diversifying during the Paleocene, the descendants of the first wave of mammals that survived the end-Cretaceous mass extinction waned throughout the Eocene. Competition with modern crown clades and intense climate fluctuations may have been part of the factors leading to the extinction of these archaic groups. Why these taxa went extinct has rarely been studied from the perspective of the nervous system. Here, we describe the first virtual endocasts for the archaic order Tillodontia. Three species from the middle Eocene of North America were analyzed: Trogosus hillsii, Trogosus grangeri, and Trogosus castoridens. We made morphological comparisons with the plaster endocast of another tillodont, Tillodon fodiens, as well as groups potentially related to Tillodontia: Pantodonta, Arctocyonidae, and Cimolesta. Trogosus shows very little inter-specific variation with the only potential difference being related to the fusion of the optic canal and sphenorbital fissure. Many ancestral features are displayed by Trogosus, including an exposed midbrain, small neocortex, orbitotemporal canal ventral to rhinal fissure, and a broad circular fissure. Potential characteristics that could unite Tillodontia with Pantodonta, and Arctocyonidae are the posterior position of cranial nerve V3 exit in relation to the cerebrum and the low degree of development of the subarcuate fossa. The presence of large olfactory bulbs and a relatively small neocortex are consistent with a terrestrial lifestyle. A relatively small neocortex may have put Trogosus at risk when competing with artiodactyls for potentially similar resources and avoiding predation from archaic carnivorans, both of which are known to have had larger relative brain and neocortex sizes in the Eocene. These factors may have possibly exacerbated the extinction of Tillodontia, which showed highly specialized morphologies despite the increase in climate fluctuations throughout the Eocene, before disappearing during the middle Eocene.

Functional connectivity of amygdala subnuclei in PTSD: a narrative review.

While the amygdala is often implicated in the neurobiology of posttraumatic stress disorder (PTSD), the pattern of results remains mixed. One reason for this may be the heterogeneity of amygdala subnuclei and their functional connections. This review used PRISMA guidelines to synthesize research exploring the functional connectivity of three primary amygdala subnuclei, basolateral (BLA), centromedial (CMA), and superficial nuclei (SFA), in PTSD (N = 331) relative to trauma-exposed (N = 155) and non-trauma-exposed controls (N = 210). Although studies were limited (N = 11), preliminary evidence suggests that in PTSD compared to trauma-exposed controls, the BLA shows greater connectivity with the dorsal anterior cingulate, an area involved in salience detection. In PTSD compared to non-trauma-exposed controls, the BLA shows greater connectivity with the middle frontal gyrus, an area involved in attention. No other connections were replicated across studies. A secondary aim of this review was to outline the limitations of this field to better shape future research. Importantly, the results from this review indicate the need to consider potential mediators of amygdala subnuclei connectivity, such as trauma type and sex, when conducting such studies. They also highlight the need to be aware of the limited inferences we can make with such small samples that investigate small subcortical structures on low field strength magnetic resonance imaging scanners. Collectively, this review demonstrates the importance of exploring the differential connectivity of amygdala subnuclei to understand the pathophysiology of PTSD and stresses the need for future research to harness the strength of ultra-high field imaging to gain a more sensitive picture of the neural connectivity underlying PTSD.

A bending rigidity parameter for stress granule condensates.

Interfacial tension plays an important role in governing the dynamics of droplet coalescence and determining how condensates interact with and deform lipid membranes and biological filaments. We demonstrate that an interfacial tension-only model is inadequate for describing stress granules in live cells. Harnessing a high-throughput flicker spectroscopy pipeline to analyze the shape fluctuations of tens of thousands of stress granules, we find that the measured fluctuation spectra require an additional contribution, which we attribute to elastic bending deformation. We also show that stress granules have an irregular, nonspherical base shape. These results suggest that stress granules are viscoelastic droplets with a structured interface, rather than simple Newtonian liquids. Furthermore, we observe that the measured interfacial tensions and bending rigidities span a range of several orders of magnitude. Hence, different types of stress granules (and more generally, other biomolecular condensates) can only be differentiated via large-scale surveys.

Golf participation after rotator cuff repair: functional outcomes, rate of return and factors associated with return to play.

BACKGROUND: Golf is a popular sport involving overhead activity and engagement of the rotator cuff (RC). This study aimed to determine to what level golfers were able to return to golf following RC repair, the barriers to them returning to golf and factors associated with their failure to return to golf. METHODS: Patients preoperatively identifying as golfers undergoing RC repair at the study centre from 2012 to 2020 were retrospectively followed up with to assess their golf-playing status, performance and frequency of play and functional and quality of life (QoL) outcomes. RESULTS: Forty-seven golfers (40 men [85.1%] and 7 women [14.9%]) with a mean age of 56.8 years met the inclusion criteria, and 80.1% were followed up with at a mean of 27.1 months postoperatively. Twenty-nine patients (76.3%) had returned to golf with a mean handicap change of +1.0 (P=0.291). Golf frequency decreased from a mean of 1.8 rounds per week preinjury to 1.5 rounds per week postoperatively (P=0.052). The EuroQol 5-dimension 5-level (EQ-5D-5L) index and visual analog scale (EQ-VAS) score were significantly greater in those returning to golf (P=0.024 and P=0.002), although functional outcome measures were not significantly different. The primary barriers to return were ipsilateral shoulder dysfunction (78%) and loss of the habit of play (22%). CONCLUSIONS: Golfers were likely (76%) to return to golf following RC repair, including mostly to their premorbid performance level with little residual symptomatology. Return to golf was associated with a greater QoL. Persistent subjective shoulder dysfunction (78%) was the most common barrier to returning to golf. Level of evidence: Level IV.

Changes in neural responses during affective and non-affective tasks and improvement of posttraumatic stress disorder symptoms following trauma-focused psychotherapy.

At least one-third posttraumatic stress disorder (PTSD) patients do not respond to trauma-focused psychotherapy (TF-psychotherapy), which is the treatment of choice for PTSD. To clarify the change mechanisms that may be associated with treatment response, this study examined changes in neural activations during affective and non-affective processing that occur with improvement of symptoms after TF-psychotherapy. This study assessed PTSD treatment-seeking patients (n = 27) prior to and after TF-psychotherapy using functional magnetic resonance imaging when they completed three tasks: (a) passive viewing of affective faces, (b) cognitive reappraisal of negative images, and (c) non-affective response inhibition. Patients then underwent 9 sessions of TF-psychotherapy, and were assessed on the Clinician-Administered PTSD Scale following treatment. Changes in neural responses in affect and cognitive processing regions-of-interest for each task were correlated with reduction of PTSD severity from pretreatment to posttreatment in the PTSD cohort. Data from 21 healthy controls was used for comparison. Improvement of symptoms in PTSD were associated with increased activation of left anterior insula, reductions in the left hippocampus and right posterior insula during viewing of supraliminally presented affective images, and reduced connectivity between the left hippocampus with the left amygdala and rostral anterior cingulate. Treatment response was also associated with reduced activation in the left dorsolateral prefrontal cortex during reappraisal of negative images. There were no associations between response and activation change during response inhibition. This pattern of findings indicates that improvement of PTSD symptoms following TF-psychotherapy is associated with changes in affective rather than non-affective processes. These findings accord with prevailing models that TF-psychotherapy promotes engagement and mastery of affective stimuli.Clinical Trials Registration: Trial Registration: Prospectively registered at Australian and New Zealand Clinical Trials Registry, ACTRN12612000185864 and ACTRN12609000324213. https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=83857.

Shifts in food webs and niche stability shaped survivorship and extinction at the end-Cretaceous.

It has long been debated why groups such as non-avian dinosaurs became extinct whereas mammals and other lineages survived the Cretaceous/Paleogene mass extinction 66 million years ago. We used Markov networks, ecological niche partitioning, and Earth System models to reconstruct North American food webs and simulate ecospace occupancy before and after the extinction event. We find a shift in latest Cretaceous dinosaur faunas, as medium-sized species counterbalanced a loss of megaherbivores, but dinosaur niches were otherwise stable and static, potentially contributing to their demise. Smaller vertebrates, including mammals, followed a consistent trajectory of increasing trophic impact and relaxation of niche limits beginning in the latest Cretaceous and continuing after the mass extinction. Mammals did not simply proliferate after the extinction event; rather, their earlier ecological diversification might have helped them survive.

Nurses' Perceptions of Medical Laboratory Scientists: Mistaken Identity and Misplaced Regard.

INTRODUCTION: The medical laboratory science (MLS) profession is an integral part of the healthcare team, providing diagnostic laboratory results used to determine directives in the treatment and management of disease processes. There is a scarcity of literature describing other healthcare professionals' perceptions of medical laboratory scientists. Research also suggests MLS professionals feel unrecognized for contributions to patient care. PURPOSE: A pilot study to describe intensive care unit (ICU) nurses' perceptions of medical laboratory scientists and their role in healthcare. METHODS: Five ICU nurses were interviewed using open-ended questions. Data were analyzed using phenomenological research inquiry to develop themes. RESULTS: Four themes were identified: professional practice, visibility, professional entry, and interprofessional learning. DISCUSSION: While participants were aware of the medical laboratory, they were unaware of the scope of practice, educational requirements, and professional credentials of medical laboratory scientists. Findings also showed misconceptions of the MLS scope of practice that overlaps with phlebotomists and medical laboratory technicians (MLTs). CONCLUSION: This study found that the intensive care nurse participants demonstrated an overall positive perception of medical laboratory scientists but a low level of knowledge of the MLS profession and expertise. Implications for interdisciplinary education to create a more comprehensive healthcare delivery team were presented.

The origin of placental mammal life histories.

After the end-Cretaceous extinction, placental mammals quickly diversified1, occupied key ecological niches2,3 and increased in size4,5, but this last was not true of other therians6. The uniquely extended gestation of placental young7 may have factored into their success and size increase8, but reproduction style in early placentals remains unknown. Here we present the earliest record of a placental life history using palaeohistology and geochemistry, in a 62 million-year-old pantodont, the clade including the first mammals to achieve truly large body sizes. We extend the application of dental trace element mapping9,10 by 60 million years, identifying chemical markers of birth and weaning, and calibrate these to a daily record of growth in the dentition. A long gestation (approximately 7 months), rapid dental development and short suckling interval (approximately 30-75 days) show that Pantolambda bathmodon was highly precocial, unlike non-placental mammals and known Mesozoic precursors. These results demonstrate that P. bathmodon reproduced like a placental and lived at a fast pace for its body size. Assuming that P. bathmodon reflects close placental relatives, our findings suggest that the ability to produce well-developed, precocial young was established early in placental evolution, and that larger neonate sizes were a possible mechanism for rapid size increase in early placentals.

The Clinical Frailty Scale can be used retrospectively to assess the frailty of patients with hip fracture: a validation study.

PURPOSE: Frailty is a common clinical syndrome affecting hip fracture patients. Recognising and accurately assessing frailty status is important in clinical and research settings. The Rockwood Clinical Frailty Scale (CFS) is a commonly used instrument and demonstrates a strong correlation with mortality and length of hospital admission following hip fracture. What is not understood, however, is the validity of retrospectively assigned CFS scores in hip fracture patients. The aim of this study was to assess the validity of retrospective non-orthogeriatrician assigned CFS scores in hip fracture patients. METHODS: Hip fracture patients from a single major trauma centre were assessed and CFS scores were assigned prospectively by non-orthogeriatric clinicians (n = 57). A subset of these patients were also assigned a prospective CFS score by a specialist orthogeriatrician (n = 27). Two separate blinded observers (non-orthogeriatric clinicians) assigned CFS scores retrospectively using electronic patient records alone. Agreement and precision was examined using the Bland-Altman plot, accuracy was assessed using R2 statistic and inter-rater reliability was assessed using quadratic weighted Cohen's kappa. RESULTS: Seventy percent of the cohort were female with an average age of 83. Agreement was high between prospective non-orthogeriatrician assigned CFS scores and retrospective non-orthogeriatrician assigned CFS scores, with a low bias (0.046) and good accuracy (R2 = 73%). Good agreement was also seen in comparisons between prospective orthogeriatrician assigned CFS scores versus retrospective non-orthogeriatrician assigned scores, with a low bias (0.23) and good accuracy (R2 = 78%). Good inter-rater reliability was seen between blinded observers with a quadratic weighted Cohen's kappa of 0.76. CONCLUSIONS: Retrospective CFS scores assigned by non-orthogeriatricians are a valid means of assessing frailty status in hip fracture patients. However, our results suggest a tendency for non-orthogeriatricians to marginally overestimate frailty status when assigning CFS scores retrospectively.

Brawn before brains in placental mammals after the end-Cretaceous extinction.

Mammals are the most encephalized vertebrates, with the largest brains relative to body size. Placental mammals have particularly enlarged brains, with expanded neocortices for sensory integration, the origins of which are unclear. We used computed tomography scans of newly discovered Paleocene fossils to show that contrary to the convention that mammal brains have steadily enlarged over time, early placentals initially decreased their relative brain sizes because body mass increased at a faster rate. Later in the Eocene, multiple crown lineages independently acquired highly encephalized brains through marked growth in sensory regions. We argue that the placental radiation initially emphasized increases in body size as extinction survivors filled vacant niches. Brains eventually became larger as ecosystems saturated and competition intensified.

Neural processes during response inhibition in complex posttraumatic stress disorder.

BACKGROUND: A common feature of complex posttraumatic stress disorder (CPTSD) is impulsivity. Despite the importance of this characteristic in functional difficulties in CPTSD, little is known about its mechanisms. The aim of this study was to identify the distinctive neural profile of CPTSD during attempted inhibition. METHODS: The present study examined functional alterations in neural networks involved in inhibitory control across functional magnetic resonance imaging (fMRI) and electroencephalogram (EEG) paradigms in CPTSD (n = 30), PTSD (n = 40), and healthy control (n = 40) participants who completed a Go/NoGo response inhibition task during separate fMRI and EEG sessions. Brain activations were calculated during the NoGo trials relative to the baseline to evaluate response inhibition functioning. RESULTS: There was reduced bilateral thalamic activation in participants with CPTSD relative to PTSD and controls during inhibition trials, but no activation differences between PTSD and controls for this brain region. There were no differences in functional connectivity between the thalamus and other regions involved in cognitive control between groups. No differences were observed between groups on EEG responses. CONCLUSIONS: These findings provide initial evidence of aberrant functioning in the neurocircuitry of inhibitory control, involving the thalamus, in CPTSD. This evidence suggests that CPTSD is distinguished from PTSD by impaired neural processes implicated in response inhibition.

Petrosal Anatomy of the Paleocene Eutherian Mammal Deltatherium fundaminis (Cope, 1881).

We describe the tympanic anatomy of the petrosal of Deltatherium fundaminis, an enigmatic Paleocene mammal based on cranial specimens recovered from New Mexico, U.S.A. Although the ear region of Deltatherium has previously been described, there has not been a comprehensive, well-illustrated contribution using current anatomical terminology. The dental and cranial anatomy of Deltatherium is a chimera, with morphological similarities to both 'condylarth' and 'cimolestan' taxa. As such, the phylogenetic relationships of this taxon have remained elusive since its discovery, and it has variably been associated with Arctocyonidae, Pantodonta and Tillodontia. The petrosal of Deltatherium is anteriorly bordered by an open space comprising a contiguous carotid opening and pyriform fenestra. The promontorium features both a small rostral tympanic process and small epitympanic wing but lacks well-marked sulci. A large ventral facing external aperture of the canaliculus cochleae is present and bordered posteriorly by a well-developed caudal tympanic process. The hiatus Fallopii opens on the ventral surface of the petrosal. The tegmen tympani is mediolaterally broad and anteriorly expanded, and its anterior margin is perforated by a foramen for the ramus superior of the stapedial artery. The tympanohyal is small but approximates the caudal tympanic process to nearly enclose the stylomastoid notch. The mastoid is widely exposed on the basicranium and bears an enlarged mastoid process, separate from the paraoccipital process. These new observations provide novel anatomical data corroborating previous hypotheses regarding the plesiomorphic eutherian condition but also reveal subtle differences among Paleocene eutherians that have the potential to help inform the phylogeny of Deltatherium. Supplementary Information: The online version contains supplementary material available at 10.1007/s10914-021-09568-3.

Quantitative assessment of tarsal morphology illuminates locomotor behaviour in Palaeocene mammals following the end-Cretaceous mass extinction.

Mammals exhibit vast ecological diversity, including a panoply of locomotor behaviours. The foundations of this diversity were established in the Mesozoic, but it was only after the end-Cretaceous mass extinction that mammals began to increase in body size, diversify into many new species and establish the extant orders. Little is known about the palaeobiology of the mammals that diversified immediately after the extinction during the Palaeocene, which are often perceived as 'archaic' precursors to extant orders. Here, we investigate the locomotor ecology of Palaeocene mammals using multivariate and disparity analyses. We show that tarsal measurements can be used to infer locomotor mode in extant mammals, and then demonstrate that Palaeocene mammals occupy distinctive regions of tarsal morphospace relative to Cretaceous and extant therian mammals, that is distinguished by their morphological robustness. We find that many Palaeocene species exhibit tarsal morphologies most comparable with morphologies of extant ground-dwelling mammals. Disparity analyses indicate that Palaeocene mammals attained similar morphospace diversity to the extant sample. Our results show that mammals underwent a post-extinction adaptive radiation in tarsal morphology relating to locomotor behaviour by combining a basic eutherian bauplan with anatomical specializations to attain considerable ecomorphological diversity.

Functional outcomes and complications following combined locking plate and tunneled suspensory device fixation of lateral-end clavicle nonunions.

BACKGROUND: Lateral-end clavicle fractures have a high rate of nonunion that can lead to ongoing pain and loss of shoulder function. The operative techniques used to manage such nonunions vary, and data on postoperative functional outcomes and complications are limited, with no consensus on the optimal surgical treatment. Our goal was to present the outcomes and complications of a new indication for combined locking plate and tunneled suspensory device fixation in the operative management of lateral-end clavicle fracture nonunions. METHODS: A consecutive series of 38 patients (mean age, 46 years; age range, 24-76 years) with symptomatic lateral-end clavicle nonunions underwent operative treatment using a new technique of anatomic locking plate combined with open reduction and tunneled suspensory device fixation between March 2011 and September 2019. Patients were assessed at a minimum of 1-year postoperative follow-up for patient-reported outcomes, range of motion, and complications. RESULTS: All patients (N = 38) achieved bony union after operative treatment. Functional outcomes were available for 34 patients. The mean Oxford Shoulder Score was 44 (standard error of the mean [SEM], 0.7), and the mean EQ-5D-3L index score was 0.784 (SEM, 0.033). Mean forward flexion was 176° (SEM, 3°); mean extension, 53° (SEM, 3°); mean combined abduction, 171° (SEM, 4°); mean internal rotation, 57° (SEM, 2°); and mean external rotation, 83° (SEM, 4°). In 2 patients (5.3%), metalwork (plate) removal was performed owing to plate prominence. CONCLUSIONS: Nonunion of lateral-end clavicle fractures can be effectively managed by combined plate and open reduction-tunneled suspensory device fixation. Excellent union rates and functional outcomes, as well as low complication rates, can be expected. The most significant complication of this technique is subsequent metalwork removal.

Neural activity during response inhibition associated with improvement of dysphoric symptoms of PTSD after trauma-focused psychotherapy-an EEG-fMRI study.

Although trauma-focused cognitive behavioural therapy (TF-CBT) is the frontline treatment for posttraumatic stress disorder (PTSD), up to one half of patients do not respond optimally to this treatment. Inhibitory functions are important for successful management of PTSD, yet there is a dearth of knowledge regarding the extent to which neural mechanisms unpinning response inhibition are associated with TF-CBT response. Treatment-seeking PTSD patients (n = 40) were assessed during a response inhibition task (the Go/No-Go task) while undergoing functional magnetic imaging (fMRI) and event-related potentials (ERP) in separate sessions. PTSD symptom severity was assessed with the Clinician-Administered PTSD Scale, before undergoing nine sessions of TF-CBT. They were then reassessed post-treatment to estimate reduction in fear and dysphoric symptoms of PTSD. Although neural responses during the inhibitory task did not predict overall symptom change, reduced activation in the left precuneus and the right superior parietal cortex predicted greater improvement in dysphoric symptoms. ERP responses during response inhibition indicated that lower P3 peak latency predicted greater reduction of dysphoric symptoms. There were no significant predictors of changes of fear symptoms. These findings indicate that neural activity associated with response inhibition can act as a predictive biomarker of TF-CBT response for PTSD symptoms. This pattern of findings underscores the importance of delineating the role of biomarkers to predict remission of subtypes of PTSD.

Neural activity during response inhibition in mild traumatic brain injury and posttraumatic stress disorder.

Mild traumatic brain injury (mTBI) is often characterized by deficits in response inhibition, which can contribute to marked social and occupational dysfunction. mTBI often occurs in the context of psychologically traumatic events. This can cause posttraumatic stress disorder (PTSD), which also impedes response inhibition. The overlap or distinction in these inhibitory deficits in mTBI and PTSD is unclear. This study aimed to assess behavioral, neurophysiological, and neuroimaging indices of response inhibition in mTBI by also assessing these parameters in healthy controls (HC) and PTSD participants. Participants with mTBI (without PTSD) (n = 46), PTSD (without mTBI) (n = 41), and HC (n = 40) were assessed during a response inhibition task (the Go/NoGo task) during neuropsychological testing and separate functional magnetic imaging and event-related potentials sessions. PTSD symptom severity was assessed with the Clinician-Administered PTSD Scale. Both mTBI and PTSD participants performed more omission errors on the Go/NoGo task and were associated with greater N2 amplitude, greater left inferior parietal activation and reduced connectivity of the left inferior parietal cluster and left angular gyrus compared to HC. There were no differences between mTBI and PTSD on any of these measures. These findings highlight that both mTBI and PTSD contribute to neural dysfunction during response inhibition, and arguably these occur due to distinct mechanisms. In the context of the common comorbidity between these two conditions, strategies to address response inhibition deficits in mTBI may need to consider causative factors underpinning neurological insult of mTBI and psychological effects associated with PTSD.