Amy J Jak's research while affiliated with University of California, San Diego and other places
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Publications (176)
Objective: Returning Veterans often have conditions (e.g. posttraumatic stress disorder [PTSD], depression, and history of traumatic brain injury [TBI]) associated with cognitive dysfunction and problems with work, school, housing, and relationships. Rehabilitative efforts in Veterans aim to promote community reintegration, or successful adjustment...
Cognitive Symptom Management and Rehabilitation Training (CogSMART) and Compensatory Cognitive Training (CCT) are evidence-based compensatory cognitive training interventions that improve cognition in persons with a history of traumatic brain injury or other neuropsychiatric disorders. Despite demonstrated efficacy, use and effectiveness of CogSMAR...
Using a diverse sample of military veterans enrolled in the Veteran Affairs (VA) Million Veteran Program ( N = 14,378; n = 1,361 females [9.5%]; all previously deployed), we examined sex differences on the Comprehensive Traumatic Brain Injury Evaluation (CTBIE), a structured traumatic brain injury (TBI) interview routinely administered in VA health...
Posttraumatic stress disorder (PTSD) treatment has been associated with improvement in quality of life (QOL); however, little is known about factors that moderate treatment‐related changes in QOL, particularly cognitive factors. Executive functioning (EF) is important for success across all aspects of everyday life and predicts better psychological...
Objective:
While outcome from mild traumatic brain injury (mTBI) is generally favorable, concern remains over potential negative long-term effects, including impaired cognition. This study examined the link between cognitive performance and remote mTBIs within the Long-term Impact of Military-relevant Brain Injury Consortium-Chronic Effects of Neu...
Objective:
The Delis-Kaplan Executive Function System (D-KEFS) Trail Making Test (TMT) is a commonly used measure of processing speed and executive functioning that may also be useful as an embedded performance validity test (PVT). We evaluated the utility of several multi-condition indices on the D-KEFS TMT in three independent samples to determi...
Objective
Cognitive practice effects (PEs) can delay detection of progression from cognitively unimpaired to mild cognitive impairment (MCI). They also reduce diagnostic accuracy as suggested by biomarker positivity data. Even among those who decline, PEs can mask steeper declines by inflating cognitive scores. Within MCI samples, PEs may increase...
Abstract Introduction Practice effects (PEs) on cognitive tests obscure decline, thereby delaying detection of mild cognitive impairment (MCI). Importantly, PEs may be present even when there are performance declines, if scores would have been even lower without prior test exposure. We assessed how accounting for PEs using a replacement‐participant...
Suicide prevention among Veterans is a national priority. Overlap exists between conditions that may increase risk for suicide (e.g., mental health conditions, financial stressors, lack of social support) and homelessness among Veterans. We examined predictors of variance in suicidal ideation (SI) among 58 Iraq/Afghanistan Veterans at risk for home...
Objective: To examine the relationship between neuropsychological functioning and
performance-based functional capacity in Veterans with a history of mild traumatic brain injury (mTBI), as well as the moderating effect of age and psychiatric symptoms on this relationship.
Setting: Three VA medical centers.
Participants: One hundred nineteen Iraq/Af...
We previously showed that failure to account for practice effects (PEs) delays detection of conversion from unimpaired to mild cognitive impairment (MCI) and reduces diagnostic accuracy based on biomarker positivity data. Even among those who decline, PE can mask steeper declines by inflating cognitive scores. Within MCI samples, PEs may increase r...
Because longitudinal studies of aging typically lack cognitive data from earlier ages, it is unclear how general cognitive ability (GCA) changes throughout the life course. In 1,173 Vietnam Era Twin Study of Aging (VETSA) participants, we assessed young adult GCA at average age 20 and current GCA at three VETSA assessments beginning at average age...
Alterations to cerebral white matter tracts have been associated with cognitive decline in aging and Alzheimer’s disease (AD). In particular, the fornix has been implicated as especially vulnerable given that it represents the primary outflow tract of the hippocampus. Despite this, little work has focused on the fornix using a potential early marke...
White matter alterations in frontolimbic circuits and poorer cognitive functioning have been observed in individuals endorsing suicidality across numerous psychiatric conditions. However, relationships between white matter integrity, cognition, and suicidality in Veterans is poorly understood, particularly for those at increased risk for suicide du...
Objective
Although emerging data suggest that women with traumatic brain injury (TBI) may suffer greater neurobehavioral dysfunction in both the post-acute and chronic phases of injury, sex differences have been severely understudied within the context of military TBI. Therefore, we examined sex differences on the Comprehensive Traumatic Brain Inju...
Objective
Executive dysfunction has previously been associated with suicidality, but it remains unclear how deficits in executive functioning contribute to increased suicidal thoughts and behaviors. Although it has been proposed that poorer executive functioning leads to difficulty generating and implementing appropriate coping strategies to regula...
Background:
Although not strongly correlated with current objective cognitive ability, subjective cognitive decline (SCD) is a risk factor for Alzheimer's disease. Most studies focus on SCD in relation to future decline rather than objective prior decline that it purportedly measures.
Objective:
We evaluated whether self-report of cognitive decl...
Neuroimaging signatures based on composite scores of cortical thickness and hippocampal volume predict progression from mild cognitive impairment to Alzheimer’s disease. However, little is known about the ability of these signatures among cognitively normal adults to predict progression to mild cognitive impairment. Towards that end, a signature se...
Objective
To examine self‐efficacy and coping style in combat‐exposed Veterans with and without mild traumatic brain injury (mTBI) history and posttraumatic stress disorder (PTSD).
Methods
Veterans (N = 81) were categorized into four groups: comorbid mTBI and PTSD (n = 23), PTSD‐only (n = 16), mTBI‐only (n = 25), and combat‐exposed controls (n = 1...
Poor sleep quality is common among Veterans with posttraumatic stress disorder (PTSD) and history of traumatic brain injury (TBI). However, the relationship between sleep quality and treatment outcomes following trauma-focused interventions is less well-understood in this population. We sought to better understand whether 1) sleep quality changed a...
Objective:
To examine associations among compensatory cognitive training (CCT), objective cognitive functioning, and self-reported cognitive symptoms. We examined whether change in objective cognitive functioning associated with participation in CCT at 10-week follow-up mediates change in self-reported cognitive symptoms associated with CCT at 15-...
Objective:
The evaluation of memory complaints in mild traumatic brain injury (mTBI) remains an important clinical consideration, especially in the context of comorbid psychiatric symptoms such as posttraumatic stress disorder (PTSD). We compared subjective memory complaints in veterans with and without a history of mTBI, examined ratings between...
Introduction:
The locus coeruleus (LC) undergoes extensive neurodegeneration in early Alzheimer's disease (AD). The LC is implicated in regulating the sleep-wake cycle, modulating cognitive function, and AD progression.
Methods:
Participants were 481 men (ages 62 to 71.7) from the Vietnam Era Twin Study of Aging. LC structural integrity was inde...
Objective:
The investigators sought to evaluate the independent and interactive associations between mild traumatic brain injury (mTBI) characteristics and posttraumatic stress disorder (PTSD) symptoms with regard to postconcussive symptoms and cognition among treatment-seeking veterans of the U.S. conflicts in Iraq and Afghanistan.
Methods:
Six...
Background
Clarifying the relationship between depression symptoms and cardiometabolic and related health could clarify risk factors and treatment targets. The objective of this study was to assess whether depression symptoms in midlife are associated with the subsequent onset of cardiometabolic health problems.
Methods
The study sample comprised...
Practice effects (PEs) mask true cognitive decline. Even with declines at follow‐up, PEs can still obscure even steeper declines. Accounting for PEs means that impairment cutoffs are reached earlier. Importantly, mild cognitive impairment (MCI) would be detected earlier. If these diagnoses are valid, there should be more biomarker‐positive MCI case...
Longitudinal studies of aging are central to identifying early predictors of and mechanisms underlying late‐life cognitive decline and dementia. However, these studies typically lack cognitive data from earlier ages. It is therefore unclear how peak young adult general cognitive ability (GCA) and maintenance of GCA from young adulthood impact subse...
Objective
Practice effects on cognitive tests obscure decline, thereby delaying detection of mild cognitive impairment (MCI). This reduces opportunities for slowing Alzheimer’s disease progression and can hinder clinical trials. Using a novel method, we assessed the ability of practice-effect-adjusted diagnoses to detect MCI earlier, and tested the...
Objective
The purpose of this study was to examine rates of “post-concussive” symptom endorsement and symptom attribution in Veterans with a history of mild traumatic brain injury (mTBI). We also explored the relationship between symptom endorsement and symptom attribution and assessed correlates of each.
Method
This cross-sectional study included...
The purpose of this study was to examine rates of and relationships between “post-concussive” symptom endorsement and symptom attribution in Veterans with a history of mild traumatic brain injury (mTBI). This cross-sectional, exploratory study included 48 combat-exposed Iraq/Afghanistan Veterans with remote history of mTBI. All Veterans completed c...
Objective
To test the hypothesis that individual differences in episodic memory and verbal fluency in cognitively normal middle-aged adults will predict progression to amnestic MCI after 6 years.
Method
The cohort analyzed here included 842 male twins who were cognitively normal at baseline (M=56 years), completed measures of episodic memory and v...
Objective:
To examine demographic, psychiatric symptom, and neuropsychological performance factors associated with duration of unemployment in Iraq/Afghanistan Veterans with a history of mild-to-moderate traumatic brain injury (TBI).
Design:
Cross-sectional, secondary data analysis of baseline measures in a supported employment study.
Setting:...
Objective: The purpose of the current study was to determine modifiable predictors of intervention adherence in a study of group-based Compensatory Cognitive Training (CCT) for Iraq/Afghanistan Veterans with a history of mild traumatic brain injury (mTBI).
Methods: One hundred twenty-three Veterans enrolled in a randomized controlled trial of a 10-...
Purpose/objective:
The purpose of this study was 2-fold: (a) to evaluate whether perception of work ability is associated with employment status in a sample of combat-exposed veterans, and (b) to determine whether the same sets of variables that are associated with employment status are also associated with perception of work ability. Research Met...
Introduction:
Predicting risk for Alzheimer's disease when most people are likely still biomarker negative would aid earlier identification. We hypothesized that combining multiple memory tests and scores in middle-aged adults would provide useful, and non-invasive, prediction of 6-year progression to MCI.
Methods:
We examined 849 men who were c...
Mild cognitive impairment (MCI) has long been conceptualized as a transitional stage between normal aging and Alzheimer’s disease (AD) and other dementia subtypes, thus providing a potential window for early intervention in at-risk older adults. Nonetheless, effective intervention requires accurate identification of prodromal dementia, and the crit...
Objective: To investigate the biological, cognitive, and psychological presentations of combat-exposed Veterans with a history of mild traumatic brain injury (mTBI) and/or posttraumatic stress disorder (PTSD) using a novel white matter imaging technique and comprehensive neuropsychological assessment.
Method: 74 Iraq and Afghanistan Veterans (mean...
Objective:
The purpose of this study was to evaluate relationships between multiple mild traumatic brain injuries (mTBIs) and objective and subjective clinical outcomes in a sample of combat-exposed Veterans, adjusting for psychiatric distress and combat exposure.
Method:
In this cross-sectional study, 73 combat-exposed Iraq/Afghanistan Veterans...
Objective:
Performance-based tests of functional capacity are rarely used in research on mild to moderate traumatic brain injury (TBI), but they may function as a link between cognitive impairment and real-world functioning. We sought to examine the relationship between cognitive functioning and performance-based functional capacity, as measured b...
Objective
Iraq and Afghanistan Veterans with posttraumatic stress disorder (PTSD) and traumatic brain injury (TBI) history have high rates of performance validity test (PVT) failure. The study aimed to determine whether those with scores in the invalid versus valid range on PVTs show similar benefit from psychotherapy and if psychotherapy improves...
Introduction:
The low mild cognitive impairment (MCI) to cognitively normal (CN) reversion rate in the Alzheimer's Disease Neuroimaging Initiative (2-3%) suggests the need to examine reversion by other means. We applied comprehensive neuropsychological criteria (NP criteria) to determine the resulting MCI to CN reversion rate.
Methods:
Participa...
Objective
The purpose of this study was to examine the influence of multiple mild traumatic brain injuries (mTBI) on objective neuropsychological functioning and subjective symptom reporting in a sample of combat-exposed Veterans.
Method
Participants included 80 combat-exposed Iraq/Afghanistan Veterans (91.3% male; age: M = 34.33, SD = 6.44) divid...
Objective
Suicidal ideation (SI) is highly prevalent in Veterans and reducing Veteran suicide is a national priority. The present study examined factors associated with SI in combat-exposed Veterans in order to inform suicide prevention efforts.
Method
Combat-exposed Iraq/Afghanistan-era Veterans (N = 77) completed questionnaires detailing demogra...
Objective
The purpose of this study was twofold: (1) to evaluate whether perception of one’s ability to work (a subjective rating) predicts employment status (an objective marker of functioning) in a sample of combat-exposed Veterans, and (2) to examine predictors of employment status and perception of work ability to determine whether the same set...
Objective
We examined whether potentially malleable factors are associated with post-concussive symptoms (PCS) and cognition in Veterans with mild traumatic brain injury (mTBI) histories.
Method
Combat-exposed Iraq and Afghanistan Veterans with remote history of mTBI (N=48) completed a neuropsychological assessment and self-report questionnaires....
Objective: The D-KEFS Color Word Interference Test (CWIT) is among the most commonly administered measures of verbally mediated processing speed and executive functioning. Previous research suggests that this test may also be sensitive to performance invalidity. We sought to develop new embedded measures of performance invalidity based on multi-con...
Objective
Test the hypothesis that individual differences in episodic memory and verbal fluency in cognitively normal middle-aged adults will predict progression to amnestic MCI after 6 years.
Method
The analysis sample included 842 male twins who were cognitively normal at baseline (M=56 years), completed measures of episodic memory and verbal fl...
BACKGROUND
The effects of traumatic brain injury (TBI) on return to work have been the focus of many clinical studies in recent years. Veterans with a history of TBI may be at increased risk of unemployment.OBJECTIVE
We sought to understand predictors of work outcomes for Veterans with a history of TBI who received evidence-based supported employme...
Introduction: Mild traumatic brain injury (mTBI) and posttraumatic stress disorder (PTSD) are highly prevalent comorbid conditions in military Veterans. However, lack of appropriate comparison groups has clouded interpretation of the chronic effects of these conditions. The present study evaluated the neuropsychological, psychiatric/neurobehavioral...
Some providers have expressed hesitation about the appropriateness of PTSD treatment for veterans with a history of mild traumatic brain injury (mTBI), given concerns that TBI-related sequelae may negatively affect PTSD treatment and/or should be the focus of treatment instead. However, research suggests that those with a history of mTBI can benefi...
![Table 2 Baseline demographic and clinical characteristics (mean [SD] or...](profile/Alexandra-Weigand-2/publication/330331090/figure/tbl2/AS:717213807939585@1548008505612/Baseline-demographic-and-clinical-characteristics-mean-SD-or-by-group_Q320.jpg)
Introduction:
We examined reasons for low mild cognitive impairment (MCI)-to-cognitively normal (CN) reversion rates in the Alzheimer's Disease Neuroimaging Initiative (ADNI).
Methods:
CN and MCI participants were identified as remaining stable, progressing, or reverting at 1-year of follow-up (Year 1). Application of ADNI's MCI criteria at Year...
Objective: Biomarkers predict risk for Alzheimer's disease, but the ability to predict when most people are still biomarker negative would foster earlier identification of risk. We hypothesized that memory testing - particularly combining multiple memory measures - in cognitively normal middle-aged adults would provide good prediction of 6-year pro...
Objective: The purpose of this review was to examine sex differences in concussion, or mild traumatic brain injury (mTBI) outcome, updating previous critical reviews of the literature.
Method: Within adult human studies, we reviewed a wide range of concussion outcome variables: prevalence of concussion, injury characteristics, postconcussion sympto...
Objective
To better concurrently address emotional and neuropsychological symptoms common in veterans with comorbid post-traumatic stress disorder (PTSD) and history of traumatic brain injury (TBI), we integrated components of compensatory cognitive training from the Cognitive Symptom Management and Rehabilitation Therapy (CogSMART) programme into...
Objective:
We evaluated the influence of the APOE-ε4 allele on post-concussive symptoms in military Veterans with a remote history of mild traumatic brain injury (mTBI).
Method:
Participants (N = 77) were administered neuropsychiatric measures, on average, approximately 5 years following their most recent mTBI and provided a DNA sample for APOE...
We retrospectively investigated archival clinical data, including correlates of lifetime homelessness, in 503 Veterans with a history of traumatic brain injuries (86.5% mild) who completed neuropsychological evaluations and passed performance validity tests. The 471 never-homeless and 32 ever-homeless Veterans were compared on demographic factors,...
Objectives:
Suicidal ideation (SI) is highly prevalent in Iraq/Afghanistan-era veterans with a history of mild traumatic brain injury (mTBI), and multiple mTBIs impart even greater risk for poorer neuropsychological functioning and suicidality. However, little is known about the cognitive mechanisms that may confer increased risk of suicidality in...
Background/aims:
Mild cognitive impairment (MCI) lacks a "gold standard" operational definition. The Jak/Bondi actuarial neuropsychological criteria for MCI are associated with improved diagnostic stability and prediction of progression to dementia compared to conventional MCI diagnostic approaches, although its utility in diagnosing MCI in old-ol...
Objective:
To determine the role of pain catastrophizing (PC) in neuropsychological functioning in veterans with a history of mild traumatic brain injury (TBI).
Participants:
Thirty-nine Iraq and Afghanistan combat veterans evaluated in the post-acute phase following mild TBI.
Methods:
Participants underwent psychiatric and TBI clinical interv...
Self-reported traumatic brain injury (TBI) is common in combat veterans, and identification of psychiatric and neuropsychological consequences following TBI has become a priority for veteran healthcare. Given the importance of accurately capturing symptoms potentially related to TBI in VA settings, validity metrics are frequently used to evaluate b...
Objective:
The objective of this study is to assess utility of in vivo myelin imaging in combat Veterans with and without history of mild traumatic brain injury (mTBI). We hypothesized that those with history of mTBI would have lower myelin water fraction (MWF), a marker of myelin integrity and content, than those without, and lower MWF would be a...
Although trauma-focused treatment, including Cognitive Processing Therapy (CPT), effectively reduces PTSD symptoms, treatment dropout, nonresponse, and relapse are substantial. Executive functioning (EF) is essential to engage the cognitive skills involved in CPT (e.g., inhibiting/evaluating distorted thoughts, flexibly generating alternative thoug...
Objective:
This study examined the Minnesota Multiphasic Personality Inventory-Second Edition-Restructured Form (MMPI-2-RF) to better understand symptom presentation in a sample of treatment-seeking Operation Enduring Freedom/Operation Iraqi Freedom (OEF/OIF) Veterans with self-reported history of mild traumatic brain injury (mTBI).
Method:
Part...
Introduction
Longitudinal testing is necessary to accurately measure cognitive change. However, repeated testing is susceptible to practice effects, which may obscure true cognitive decline and delay detection of mild cognitive impairment (MCI).
Methods
We retested 995 late-middle-aged men in a ∼6-year follow-up of the Vietnam Era Twin Study of Ag...
Primary Objective: About 20% of Iraq and Afghanistan Veterans have sustained a traumatic brain injury (TBI), which can result in postconcussive symptoms and difficulty transitioning from the military to civilian employment and postsecondary education. To better inform programs help Veterans transition back into civilian life, we evaluated correlate...
Background:
Working memory (WM) is often assessed with serial order tests such as repeating digits backward. In prior dementia research using the Backward Digit Span Test (BDT), only aggregate test performance was examined.
Objective:
The current research tallied primacy/recency effects, out-of-sequence transposition errors, perseverations, and...
Opinion statement
Symptoms that persist beyond the expected period of recovery following a mild traumatic brain injury (mTBI)/concussion are strongly linked to non-neurologic variables, notably mental health conditions such as posttraumatic stress disorder (PTSD), particularly among Iraq and Afghanistan Veterans. Despite acknowledgement of poor rec...
Objective:
We examined BOLD (Blood-Oxygen-Level Dependent) activity reduction upon stimuli repetition of face-name pairs in older adults with amnestic (aMCI) and non-amnestic (naMCI) mild cognitive impairment diagnosed using a comprehensive actuarial method, and relationships between activity reduction and behavioral indices.
Method:
Twenty-nine...
Objective:
Posttraumatic stress disorder (PTSD), history of mild traumatic brain injury (mTBI), and executive function (EF) difficulties are prevalent in Operation Enduring Freedom/Operation Iraqi Freedom (OEF/OIF) Veterans. We evaluated the contributions of injury variables, lower-order cognitive component processes (processing speed/attention),...
Task-evoked pupillary responses may be a psychophysiological biomarker of early risk for mild cognitive impairment (MCI) and Alzheimer's disease (AD). Pupil dilation during cognitive tasks reflects cognitive effort until compensatory capacity is surpassed and performance declines are manifest, and reflects activation in the locus coeruleus, where d...
Post-traumatic stress disorder (PTSD) is classified as a traumatic stress-related condition and is most often discussed in terms of emotional dysfunction. However, given that cognitive and emotional processes are intricately intertwined, implemented by overlapping brain networks, and effectively integrated in at least some of the same regions (e.g....
Background: Difficulty providing accurate diagnosis and prognosis, especially after mild forms of traumatic brain injury (TBI), has increased efforts to detect changes in white matter microstructure using advanced neuroimaging techniques. Although methods such as diffusion tensor imaging (DTI) have greatly increased knowledge of white matter change...
Post-traumatic fatigue (PTF) is a common, disabling, and often chronic symptom following traumatic brain injury (TBI). Yet, the impact of chronic cognitive and physical fatigue and their associations with psychiatric, sleep, cognitive, and psychosocial sequelae in mild-moderate TBI remain poorly understood. Sixty Veterans with a history of mild-mod...
Introduction:
Given that little is known about the associations between alcohol use, cognition, and psychiatric symptoms among veterans with a history of mild traumatic brain injury (mTBI), we aimed to (a) characterize how they differ from veteran controls on a measure of problem drinking; (b) investigate whether problem drinking is associated wit...
Mild cognitive impairment (MCI) is typically diagnosed using subjective complaints, screening measures, clinical judgment, and a single memory score. Our prior work has shown that this method is highly susceptible to false-positive diagnostic errors. We examined whether the criteria also led to "false-negative" errors by diagnostically reclassifyin...
Objectives:
To refine mild cognitive impairment (MCI) diagnostic criteria, we examined progression to dementia using two approaches to identifying MCI.
Methods:
A total of 1203 Framingham Heart Study participants were classified at baseline as cognitively normal or MCI (overall and four MCI subtypes) via conventional Petersen/Winblad criteria (s...