Traumatic brain injury alters neuropsychiatric symptomatology in all-cause dementia

Targeting cis-p-tau and neuro-related gene expression in traumatic brain injury: therapeutic insights from TC-DAPK6 treatment in mice

BACKGROUND

Traumatic brain injury (TBI) is a significant global health concern and is characterized by brain dysfunction resulting from external physical forces, leading to brain pathology and neuropsychiatric disorders such as anxiety. This study investigates the effects of TC-DAPK6 on tau hyper-phosphorylation, gene expression, anxiety, and behavior impairment in the TBI mice model.

METHODS AND RESULTS

A weight drop model induced the TBI and the anxiety levels were evaluated using an elevated plus maze (EPM) test. TC-DAPK6 was intraperitoneally administered one-month post-TBI and continued for two months. The total cis-p-tau ratio in the brain was assessed using western blot and immunofluorescence staining. Molecular analysis was conducted on Aff2, Zkscan16, Kcna1, Pcdhac2, and Pcdhga8 to investigate the function and pathogenic role of TC-DAPK6 in neurological diseases in the cerebral cortex tissues of TBI-model mice, and the results were compared with TC-DAPK6 TBI-treatment group. The anxiety level and phosphorylation of tau protein in the TBI group were significantly increased compared to the sham groups and decreased substantially in the TBI-treatment group after TC-DAPK6 administration; the TBI group mostly spent their time with open arms. TC-DAPK6 decreased the expression level of genes as much as the sham group. Meanwhile, KCNA1 showed the highest fold of changes in the TBI and TBI-treatment groups.

CONCLUSIONS

The study demonstrates a clear association between cis-p-tau and neuro-related gene expression levels in TBI-induced mice. Targeting these pathways with DAPK1 inhibitors, shows promise for therapeutic interventions in TBI and related neurodegenerative disorders.

Increasing Risk of Dementia Among Patients with Subsequent Epilepsy Within 2 Years Post-Traumatic Brain Injury: A Population-Based Case-Control Study

Background

Although the association between neurodegenerative diseases, such as dementia, and traumatic brain injury (TBI) has long been known, the association between dementia and TBI with epilepsy has been controversial.

Aim

This data-driven population-based study is designed to investigate the association between dementia and epilepsy after TBI within a 2-year period.

Methods

This case-control cohort study was conducted using the Longitudinal Health Insurance Database 2000 (LHID2000). We included 784 individuals ambulatory or hospitalized for TBI with epilepsy from 2001 to 2011, compared with 2992 patients with TBI without epilepsy who were matched for characteristics including sex, age, and healthcare resource use index date. Every participant was followed up for 5 years to ascertain any dementia development. Data were stratified and analyzed using the Cox proportional hazards regression.

Results

Through the 5-year follow-up period, 39 patients (5.21%) with TBI with epilepsy and 55 (1.53%) with TBI without epilepsy developed dementia. TBI with epilepsy was independently associated with a >3.03 times risk of dementia after correcting for age, sex, and comorbidities.

Conclusion

These findings suggest an increased risk of dementia in patients with TBI with epilepsy. Our research recommends that individuals with TBI and epilepsy be monitored more intensively.

Associations of Prior Head Injury With Mild Behavioral Impairment Domains

OBJECTIVE

This study investigated associations of prior head injury and number of prior head injuries with mild behavioral impairment (MBI) domains.

SETTING

The Atherosclerosis Risk in Communities (ARIC) Study.

PARTICIPANTS

A total of 2534 community-dwelling older adults who took part in the ARIC Neurocognitive Study stage 2 examination were included.

DESIGN

This was a prospective cohort study. Head injury was defined using self-reported and International Classification of Diseases, Ninth Revision ( ICD -9) code data. MBI domains were defined using the Neuropsychiatric Inventory Questionnaire (NPI-Q) via an established algorithm mapping noncognitive neuropsychiatric symptoms to the 6 domains of decreased motivation, affective dysregulation, impulse dyscontrol, social inappropriateness, and abnormal perception/thought content.

MAIN MEASURES

The primary outcome was the presence of impairment in MBI domains.

RESULTS

Participants were a mean age of 76 years, with a median time from first head injury to NPI-Q administration of 32 years. The age-adjusted prevalence of symptoms in any 1+ MBI domains was significantly higher among individuals with versus without prior head injury (31.3% vs 26.0%, P = .027). In adjusted models, a history of 2+ head injuries, but not 1 prior head injury, was associated with increased odds of impairment in affective dysregulation and impulse dyscontrol domains, compared with no history of head injury (odds ratio [OR] = 1.83, 95% CI = 1.13-2.98, and OR = 1.74, 95% CI = 1.08-2.78, respectively). Prior head injury was not associated with symptoms in MBI domains of decreased motivation, social inappropriateness, and abnormal perception/thought content (all P > .05).

CONCLUSION

Prior head injury in older adults was associated with greater MBI domain symptoms, specifically affective dysregulation and impulse dyscontrol. Our results suggest that the construct of MBI can be used to systematically examine the noncognitive neuropsychiatric sequelae of head injury; further studies are needed to examine whether the systematic identification and rapid treatment of neuropsychiatric symptoms after head injury is associated with improved outcomes.

Inflammaging, cellular senescence, and cognitive aging after traumatic brain injury

Traumatic brain injury (TBI) is associated with mortality and morbidity worldwide. Accumulating pre-clinical and clinical data suggests TBI is the leading extrinsic cause of progressive neurodegeneration. Neurological deterioration after either a single moderate-severe TBI or repetitive mild TBI often resembles dementia in aged populations; however, no currently approved therapies adequately mitigate neurodegeneration. Inflammation correlates with neurodegenerative changes and cognitive dysfunction for years post-TBI, suggesting a potential association between immune activation and both age- and TBI-induced cognitive decline. Inflammaging, a chronic, low-grade sterile inflammation associated with natural aging, promotes cognitive decline. Cellular senescence and the subsequent development of a senescence associated secretory phenotype (SASP) promotes inflammaging and cognitive aging, although the functional association between senescent cells and neurodegeneration is poorly defined after TBI. In this mini-review, we provide an overview of the pre-clinical and clinical evidence linking cellular senescence with poor TBI outcomes. We also discuss the current knowledge and future potential for senotherapeutics, including senolytics and senomorphics, which kill and/or modulate senescent cells, as potential therapeutics after TBI.

Effect of traumatic brain injury on mild behavioral impairment domains prior to all-cause dementia diagnosis and throughout disease progression

Introduction

Traumatic brain injury (TBI) may alter dementia progression, although co-occurring neuropsychiatric symptoms (NPS) have received less attention. Originally designed to evaluate behavioral disruption prior to dementia diagnosis, the mild behavioral impairment (MBI) construct relates NPS to underlying neural circuit disruptions, with probable relevance across the progression of neurodegenerative disease. Therefore, the MBI construct may represent a valuable tool to identify and evaluate related NPS both preceding diagnosis of all-cause dementia throughout the progression of disease, representing an important area of inquiry regarding TBI and dementia. This investigation sought to evaluate the effect of TBI on NPS related by the MBI construct in participants progressing from normal cognitive status to all-cause dementia.

Methods

Using National Alzheimer's Coordinating Center data, individuals progressing from normal cognition to all-cause dementia (clinician diagnosed) over 7.6 ± 3.0 years were studied to estimate prevalence of MBI domains in 124 participants with prior TBI history (57 with loss of consciousness [LOC] <5 minutes, 22 with LOC >5 min, 45 unknown severity) compared to 822 without. MBI domain prevalence was evaluated (1) prior to dementia onset (including only time points preceding time at dementia diagnosis, as per MBI's original definition) and (2) throughout dementia progression (evaluating all available time points, including both before and after dementia diagnosis).

Results

More severe TBI (LOC >5 minutes) was associated with the social inappropriateness MBI domain (adjusted odds ratio = 4.034; P = 0.024) prior to dementia onset, and the abnormal perception/thought content domain looking across dementia progression (adjusted hazard ratio [HRadj] = 3.703; P = 0.005). TBI (all severities) was associated with the decreased motivation domain looking throughout dementia progression (HRadj. = 1.546; P = 0.014).

Discussion

TBI history is associated with particular MBI profiles prior to onset and throughout progression of dementia. Understanding TBI's impact on inter-related NPS may help elucidate underlying neuropathology with implications for surveillance, detection, and treatment of behavioral concerns in aging TBI survivors.

Highlights

The mild behavioral impairment (MBI) construct links related neuropsychiatric symptoms (NPS) by probable underlying neural network dysfunction.Traumatic brain injury (TBI) with loss of consciousness (LOC) > 5 minutes was associated with pre-dementia social inappropriateness.TBI was associated with decreased motivation looking across dementia progression.TBI with LOC > 5 minutes was associated with abnormal perception/thought content.The MBI construct may be useful for examining related NPS across dementia progression.

Traumatic Brain Injury and Secondary Neurodegenerative Disease

Traumatic brain injury (TBI) is a devastating event with severe long-term complications. TBI and its sequelae are one of the leading causes of death and disability in those under 50 years old. The full extent of secondary brain injury is still being intensely investigated; however, it is now clear that neurotrauma can incite chronic neurodegenerative processes. Chronic traumatic encephalopathy, Parkinson's disease, and many other neurodegenerative syndromes have all been associated with a history of traumatic brain injury. The complex nature of these pathologies can make clinical assessment, diagnosis, and treatment challenging. The goal of this review is to provide a concise appraisal of the literature with focus on emerging strategies to improve clinical outcomes. First, we review the pathways involved in the pathogenesis of neurotrauma-related neurodegeneration and discuss the clinical implications of this rapidly evolving field. Next, because clinical evaluation and neuroimaging are essential to the diagnosis and management of neurodegenerative diseases, we analyze the clinical investigations that are transforming these areas of research. Finally, we briefly review some of the preclinical therapies that have shown the most promise in improving outcomes after neurotrauma.

Early Aβ42 Exposure Causes Learning Impairment in Later Life

Amyloid cascade hypothesis proposes that amyloid β (Aβ) accumulation is the initiator and major contributor to the development of Alzheimer’s disease (AD). However, this hypothesis has recently been challenged by clinical studies showing that reduction of Aβ accumulation in the brain does not accompany with cognitive improvement, suggesting that therapeutically targeting Aβ in the brain may not be sufficient for restoring cognitive function. Since the molecular mechanism underlying the progressive development of cognitive impairment after Aβ clearance is largely unknown, the reason of why there is no behavioral improvement after Aβ clearance remains elusive. In the current study, we demonstrated that transient Aβ expression caused learning deficit in later life, despite the accumulated Aβ was soon being removed after the expression. Early Aβ exposure decreased the cellular expression of XBP1 and both the antioxidants, catalase, and dPrx5, which made cells more vulnerable to oxidative stress in later life. Early induction of XBP1, catalase, and dPrx5 prevented the overproduction of ROS, improved the learning performance, and preserved the viability of cells in the later life with the early Aβ induction. Treating the early Aβ exposed flies with antioxidants such as vitamin E, melatonin and lipoic acid, after the removal of Aβ also preserved the learning ability in later life. Taken together, we demonstrated that early and transient Aβ exposure can have a profound impact on animal behavior in later life and also revealed the cellular and molecular mechanism underlying the development of learning impairment by the early and transient Aβ exposure.

Effect of Weight Class on Regional Brain Volume, Cognition, and Other Neuropsychiatric Outcomes among Professional Fighters

Traumatic brain injury (TBI) is a common source of functional impairment among athletes, military personnel, and the general population. Professional fighters in both boxing and mixed martial arts (MMA) are at particular risk for repetitive TBI and may provide valuable insight into both the pathophysiology of TBI and its consequences. Currently, effects of fighter weight class on brain volumetrics (regional and total) and functional outcomes are unknown. Fifty-three boxers and 103 MMA fighters participating in the Professional Fighters Brain Health Study (PRBHS) underwent volumetric magnetic resonance imaging (MRI) and neuropsychological testing. Fighters were divided into lightweight (≤139.9 lb), middleweight (140.0–178.5 lb), and heavyweight (>178.5 lb). Compared with lightweight fighters, heavyweights displayed greater yearly reductions in regional brain volume (boxers: bilateral thalami; MMA: left thalamus, right putamen) and functional performance (boxers: processing speed, simple and choice reaction; MMA: Trails A and B tests). Lightweights suffered greater reductions in regional brain volume on a per-fight basis (boxers: left thalamus; MMA: right putamen). Heavyweight fighters bore greater yearly burden of regional brain volume and functional decrements, possibly related to differing fight dynamics and force of strikes in this division. Lightweights demonstrated greater volumetric decrements on a per-fight basis. Although more research is needed, greater per-fight decrements in lightweights may be related to practices of weight-cutting, which may increase vulnerability to neurodegeneration post-TBI. Observed decrements associated with weight class may result in progressive impairments in fighter performance, suggesting interventions mitigating the burden of TBI in professional fighters may both improve brain health and increase professional longevity.

Hippocampal atrophy is associated with psychotic symptom severity following traumatic brain injury

Psychosis is a rare, but particularly serious sequela of traumatic brain injury. However, little is known as to the neurobiological processes that may contribute to its onset. Early evidence suggests that psychotic symptom development after traumatic brain injury may co-occur with hippocampal degeneration, invoking the possibility of a relationship. Particularly regarding the hippocampal head, these degenerative changes may lead to dysregulation in dopaminergic circuits, as is reported in psychoses due to schizophrenia, resulting in the positive symptom profile typically seen in post-injury psychosis. The objective of this study was to examine change in hippocampal volume and psychotic symptoms across time in a sample of moderate-to-severe traumatic brain injury patients. We hypothesized that hippocampal volume loss would be associated with increased psychotic symptom severity. From a database of n = 137 adult patients with prospectively collected, longitudinal imaging and neuropsychiatric outcomes, n = 24 had complete data at time points of interest (5 and 12 months post-traumatic brain injury) and showed increasing psychotic symptom severity on the Personality Assessment Inventory psychotic experiences subscale of the schizophrenia clinical scale across time. Secondary analysis employing stepwise regression with hippocampal volume change (independent variable) and Personality Assessment Inventory psychotic symptom change (dependent variable) from 5 to 12 months post-injury was conducted including age, sex, marijuana use, family history of schizophrenia, years of education and injury severity as control variables. Total right hippocampal volume loss predicted an increase in the Personality Assessment Inventory psychotic experiences subscale (F_{(1, 22)} = 5.396, adjusted R² = 0.161, P = 0.030; β = −0.017, 95% confidence interval = −0.018, −0.016) as did volume of the right hippocampal head (F_{(1, 22)} = 5.764, adjusted R² = 0.172, P = 0.025; β = −0.019, 95% confidence interval = −0.021, −0.017). Final model goodness-of-fit was confirmed using k-fold (k = 5) cross-validation. Consistent with our hypotheses, the current findings suggest that hippocampal degeneration in the chronic stages of moderate-to-severe traumatic brain injury may play a role in the delayed onset of psychotic symptoms after traumatic brain injury. These findings localized to the right hippocampal head are supportive of a proposed aetiological mechanism whereby atrophy of the hippocampal head may lead to the dysregulation of dopaminergic networks following traumatic brain injury; possibly accounting for observed clinical features of psychotic disorder after traumatic brain injury (including prolonged latency period to symptom onset and predominance of positive symptoms). If further validated, these findings may bear important clinical implications for neurorehabilitative therapies following traumatic brain injury.