Evidence of cognitive decline in older adults after remote traumatic brain injury: an exploratory study

Detecting and Predicting Cognitive Decline in Individuals with Traumatic Brain Injury: A Longitudinal Telephone-Based Study

Traumatic brain injuries (TBIs) can lead to long-lasting cognitive impairments, and some survivors experience cognitive decline post-recovery. Early detection of decline is important for care planning, and understanding risk factors for decline can elucidate targets for prevention. While neuropsychological testing is the gold standard approach to characterizing cognitive function, there is a need for brief, scalable tools that are capable of detecting clinically significant changes in post-TBI cognition. This study examines whether a clinically significant change can be detected using the Brief Test of Adult Cognition by Telephone (BTACT) in a sample of individuals with chronic TBI and investigates whether potentially modifiable factors are associated with cognitive decline. Ninety participants aged 40 or older with complicated mild-to-severe TBI participated in two telephone-based study visits ∼1 year apart. Demographic, head trauma exposure, comorbid medical conditions, physical, and psychosocial functioning data were collected via self-report. The BTACT, a brief measure of global cognitive function, was used to assess cognitive performance across six domains. A reliable change index for quantifying clinically significant changes in BTACT performance was calculated. Results revealed cognitive decline in 10-27% of participants across various cognitive domains. More specifically, only depressive symptoms, including depressed affect and anhedonia, were significantly associated with cognitive decline after correcting for multiple comparisons using false discovery rate (FDR). Other factors such as the number of blows to the head, male gender, dyspnea, increased anxiety symptoms, seizures, illicit drug use, and fewer cardiovascular comorbidities should be considered hypothesis generating. Importantly, age was not a significant predictor of cognitive decline, which challenges the assumption that cognitive decline is solely related to the natural aging process. It suggests that there are unique factors associated with TBI that impact cognitive function, and these factors can affect individuals across the lifespan. The BTACT is a brief and sensitive tool for identifying clinically meaningful changes in cognitive function over a relatively brief period (i.e., 1 year) in a sample of individuals in the chronic stages of TBI (i.e., x̄ = 6.7 years post-TBI). Thus, the BTACT may be useful in surveillance efforts aimed at understanding and detecting decline, particularly in situations where in-person cognitive screening is impractical or unfeasible. We also identified potentially modifiable targets for the prevention of post-TBI cognitive decline. These findings can offer insights into treatment goals and preventive strategies for individuals at risk for cognitive decline, as well as help to facilitate early identification efforts.

Long-term cognitive and affective consequences of mild traumatic brain injury: comparison with older adults

OBJECTIVE

Memory and affective processing were compared in young adults with a remote mild traumatic brain injury (mTBI), to healthy younger and older adults. We evaluated memory performance when encoding was done under multi-tasking (divided attention) conditions, likely to exacerbate cognitive and psychological symptoms in mTBI.

METHODS

Participants studied pairs of unrelated words under either full or divided attention conditions. Memory for single words (item memory) and for pairs of words (associative memory) was then assessed in sequential independent recognition tests, under full attention.

RESULTS

Associative memory was poorer than item memory, and worse when encoding was done under divided than full attention. The decline in recognition accuracy from full to divided attention conditions on the associative memory test was significantly greater in mTBI compared to young adults and was similar in magnitude to that observed in older adults under full attention. Self-reported mental and total fatigue increased significantly as performance on the memory tests, following the divided attention condition, decreased, but only in the mTBI group.

CONCLUSIONS

Results show lingering memory deficits, and suggest that cognitive tasks may be experienced as psychologically more demanding in those with a mTBI, even months or years after injury.

The Role of Incarceration as a Risk Factor for Cognitive Impairment

OBJECTIVES

The objective of this study was to understand disparities in cognitive impairment between middle-aged formerly incarcerated (FI) and nonincarcerated individuals.

METHODS

The 1979 National Longitudinal Survey of Youth is a nationally representative longitudinal data set containing information on incarceration, cognitive functioning, and other health conditions. Using a modified version of the Telephone Interview for Cognitive Status (TICS-m), adapted from the Health and Retirement Study, we analyzed the association between incarceration and cognitive impairment, cognitive impairment-not dementia and dementia. Multivariable regression models were estimated, including prior incarceration status and covariates associated with incarceration and cognitive functioning.

RESULTS

FI individuals had lower unadjusted scores on TICS-m (-2.5, p < .001) and had significantly greater unadjusted odds ratios (OR) for scoring in the cognitive impairment (OR = 2.4, p < .001) and dementia (OR = 2.7, p < .001) range. Differences were largely explained by a combination of risk factors associated with incarceration and cognition. Education and premorbid cognition (measured by Armed Forces Qualification Test) separately and completely explained differences in the odds of dementia. Regardless of incarceration status, Blacks and Hispanics had significantly greater odds of cognitive impairment and dementia relative to Whites, holding other factors constant.

DISCUSSION

The association between prior incarceration and cognitive impairment in middle age was largely explained by differences in educational attainment and premorbid cognitive functioning, supporting the cognitive reserve hypothesis. Greater prevalence of cognitive impairment and dementia among the FI could create challenges and should be considered in reentry planning. Structural and institutional factors should be considered when addressing health disparities in Alzheimer's Disease and Related Dementias.

Does Mild Traumatic Brain Injury Increase the Risk for Dementia? A Systematic Review and Meta-Analysis

Background: Mild traumatic brain injury (mTBI) is a putative risk factor for dementia; however, despite having apparent face validity, the evidence supporting this hypothesis remains inconclusive. Understanding the role of mTBI as a risk factor is becoming increasingly important given the high prevalence of mTBI, and the increasing societal burden of dementia. Objective: Our objective was to use the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) format to determine if an association exists between mTBI and dementia and related factors, and to quantify the degree of risk. Methods: In this format, two authors conducted independent database searches of PubMed, PsycInfo, and CINAHL using three search blocks to find relevant papers published between 2000 and 2020. Relevant studies were selected using pre-defined inclusion/exclusion criteria, and bias scoring was performed independently by the two authors before a subset of studies was selected for meta-analysis. Twenty-one studies met the inclusion criteria for this systematic review. Results: The meta-analysis yielded a pooled odds ratio of 1.96 (95% CI 1.698–2.263), meaning individuals were 1.96 times more likely to be diagnosed with dementia if they had a prior mTBI. Most studies examining neuropsychiatric and neuroimaging correlates of dementia found subtle, persistent changes after mTBI. Conclusion: These results indicate that mTBI is a risk factor for the development of dementia and causes subtle changes in performance on neuropsychiatric testing and brain structure in some patients.

Astrocyte dysfunction and neurovascular impairment in neurological disorders: Correlation or causation?

The neurovascular unit, consisting of neurons, astrocytes, and vascular cells, has become the focus of much discussion in the last two decades and emerging literature now suggests an association between neurovascular dysfunction and neurological disorders. In this review, we synthesize the known and suspected contributions of astrocytes to neurovascular dysfunction in disease. Throughout the brain, astrocytes are centrally positioned to dynamically mediate interactions between neurons and the cerebral vasculature, and play key roles in blood-brain barrier maintenance and neurovascular coupling. It is increasingly apparent that the changes in astrocytes in response to a variety of insults to brain tissue -collectively referred to as "reactive astrogliosis" - are not just an epiphenomenon restricted to morphological alterations, but comprise functional changes in astrocytes that contribute to the phenotype of neurological diseases with both beneficial and detrimental effects. In the context of the neurovascular unit, astrocyte dysfunction accompanies, and may contribute to, blood-brain barrier impairment and neurovascular dysregulation, highlighting the need to determine the exact nature of the relationship between astrocyte dysfunction and neurovascular impairments. Targeting astrocytes may represent a new strategy in combinatorial therapeutics for preventing the mismatch of energy supply and demand that often accompanies neurological disorders.

Prevalence and correlates of traumatic brain injury (TBI) in older adults: results from the Well-being of the Singapore Elderly (WiSE) study

BACKGROUND

Older adults are among the most susceptible to sustain traumatic brain injury (TBI). The study aimed to determine the (1) prevalence of TBI among older adults in Singapore, and (2) socio-demographic, lifestyle, and clinical correlates of TBI.

METHODS

Data were extracted from the cross-sectional, Well-being of the Singapore Elderly (WiSE) study. The study included 2,565 participants aged 60 years and above (Mean = 72.75, SD = 9.54). Information on TBI, socio-demographic, and lifestyle factors were collected using participant self-report and verified with the informant report where necessary. Disability was measured using the World Health Organization - Disability Assessment Schedule 2.0 (WHO-DAS 2.0). Data were analyzed using logistic regression analysis.

RESULTS

The prevalence of TBI was 3.6%. Being female (vs. male) was found to be associated with decreased odds of having TBI. Having completed secondary education or lower (vs. tertiary education) was found to be associated with increased odds of having TBI. A history of fainting and diabetes were associated with the presence of TBI. Those with TBI were associated with higher disability scores on the WHO-DAS 2.0 than those without TBI.

CONCLUSIONS

The current study provides information on the prevalence and associated factors of TBI in the older adult population in Singapore. Since TBI was associated with older adults with diabetes, they must be cautioned about fall risk. Also, given the association with disability, older adults with TBI are likely to require support and rehabilitative care to ensure good quality of life.

Self-reported traumatic brain injury and in vivo measure of AD-vulnerable cortical thickness and AD-related biomarkers in the ADNI cohort

In this study, we aimed to investigate whether self-reported mild traumatic brain injury (mTBI) was associated with decreased AD-vulnerable cortical thickness, and to assess the relationship between AD-vulnerable cortical thickness and AD-related biomarker in the Alzheimer's Disease Neuroimaging Initiative subjects. We identified 45 self-reported mTBI subjects, who had structural MRI, 18F-AV45 PET, and cerebrospinal fluid (CSF) data. Of them, eight subjects were normal; ten were preclinical AD; seventeen were MCI due to AD; ten were AD. Additional demographics-controlled 45 subjects were included. Cortical thickness of eight AD-vulnerable regions, mean AD-vulnerable cortical thickness, 18F-AV45 PET mean amyloid SUVR, CSF Aβ42, CSF total tau (T-tau), and CSF phosphorylated tau (P-tau) were compared between mTBI and non-TBI groups. Correlational analysis was done to investigate the relationship between mean AD-vulnerable cortical thickness and mean amyloid SUVR, CSF Aβ42, CSF T-Tau, CSF P-Tau. Our study revealed that preclinical AD subjects with self-reported mTBI had smaller cortical thickness in mean and three AD-vulnerable cortical regions than non-TBI subjects (P<0.05). The mean AD-vulnerable cortical thickness was correlated with CSF T-tau (r=-0.81, P=0.001). There was no statistical difference in the comparison of normal, MCI due to AD, and AD groups. Our study indicated that among individuals with preclinical AD, but not normal, MCI due to AD and AD subjects, self-reported mTBI was associated with more decreased AD-vulnerable cortical thickness which was related to CSF tau pathology, suggesting the possible early involvement of tau pathology in the decreased AD-vulnerable cortical thickness of self-reported TBI subjects.

Increased risk for age-related impairment in visual attention associated with mild traumatic brain injury: Evidence from saccadic response times

It was hypothesized that risk for age-related impairment in attention would be greater among those with remote history of mild TBI than individuals without history of head injury. Twenty-seven adults with remote history of mild TBI and a well-matched comparison group of 54 uninjured controls completed a computerized test of visual attention while saccadic and manual response times were recorded. Within the mild TBI group only, older age was associated with slower saccadic responses and poorer saccadic inhibition. Saccadic slowing was mitigated in situations where the timing and location of attention targets was fully predictable. Mild TBI was not associated with age-related increases in risk for neuropsychological impairment or neurobehavioral symptoms. These results provide preliminary evidence that risk for age-related impairment in visual attention may be higher among those with a history of mild TBI. Saccadic measures may provide enhanced sensitivity to this subtle form of cognitive impairment.

Aging with Traumatic Brain Injury: Effects of Age at Injury on Behavioral Outcome following Diffuse Brain Injury in Rats

Development and aging are influenced by external factors with the potential to impact health throughout the life span. Traumatic brain injury (TBI) can initiate and sustain a lifetime of physical and mental health symptoms. Over 1.7 million TBIs occur annually in the USA alone, with epidemiology suggesting a higher incidence for young age groups. Additionally, increasing life spans mean more years to age with TBI. While there is ongoing research of experimental pediatric and adult TBI, few studies to date have incorporated animal models of pediatric, adolescent, and adult TBI to understand the role of age at injury across the life span. Here, we explore repeated behavioral performance between rats exposed to diffuse TBI at five different ages. Our aim was to follow neurological morbidities across the rodent life span with respect to age at injury. A single cohort of male Sprague-Dawley rats (n = 69) was received at postnatal day (PND) 10. Subgroups of this cohort (n = 11-12/group) were subjected to a single moderate midline fluid percussion injury at age PND 17, PND 35, 2 months, 4 months, or 6 months. A control group of naïve rats (n = 12) was assembled from this cohort. The entire cohort was assessed for motor function by beam walk at 1.5, 3, 5, and 7 months of age. Anxiety-like behavior was assessed with the open field test at 8 months of age. Cognitive performance was assessed using the novel object location task at 8, 9, and 10 months of age. Depression-like behavior was assessed using the forced swim test at 10 months of age. Age at injury and time since injury differentially influenced motor, cognitive, and affective behavioral outcomes. Motor and cognitive deficits occurred in rats injured at earlier developmental time points, but not in rats injured in adulthood. In contrast, rats injured during adulthood showed increased anxiety-like behavior compared to uninjured control rats. A single diffuse TBI did not result in chronic depression-like behaviors or changes in body weight among any groups. The interplay of age at injury and aging with an injury are translationally important factors that influence behavioral performance as a quality of life metric. More complete understanding of these factors can direct rehabilitative efforts and personalized medicine for TBI survivors.