Neuropsychological Effects of Self-Reported Deployment-Related Mild TBI and Current PTSD in OIF/OEF Veterans

Current combat veterans are exposed to many incidents that may result in mild traumatic brain injury (mTBI) and/or posttraumatic stress disorder (PTSD). While there is literature on the neuropsychological consequences of PTSD only (PTSD-o) and mTBI alone (mTBI-o), less has been done to explore their combined (mTBI+PTSD) effect. The goal of this study was to determine whether Operation Iraqi Freedom (OIF) and Operation Enduring Freedom (OEF) veterans with mTBI+PTSD have poorer cognitive and psychological outcomes than veterans with PTSD-o, mTBI-o, or combat exposure-only. The final sample included 20 OIF/OEF veterans with histories of self-reported deployment mTBI (mTBI-o), 19 with current PTSD (PTSD-o), 21 with PTSD and self-reported mTBI (mTBI+PTSD), and 21 combat controls (CC) (no PTSD and no reported mTBI). Groups were formed using structured interviews for mTBI and PTSD. All participants underwent comprehensive neuropsychological testing, including neurocognitive and psychiatric feigning tests. Results of cognitive tests revealed significant differences in performance in the mTBI+PTSD and PTSD-o groups relative to mTBI-o and CC. Consistent with previous PTSD literature, significant differences were found on executive (switching) tasks, verbal fluency, and verbal memory. Effect sizes tended to be large in both groups with PTSD. Thus, PTSD seems to be an important variable affecting neuropsychological profiles in the post-deployment time period. Consistent with literature on civilian mTBI, the current study did not find evidence that combat-related mTBI in and of itself contributes to objective cognitive impairment in the late stage of injury.     

Pattern of cognitive impairment in older veterans with posttraumatic stress disorder evaluated at a memory disorders clinic

Background: We determined the pattern of clinically significant cognitive impairment (CI) among older veterans with posttraumatic stress disorder (PTSD) evaluated in a memory disorders clinic. Methods: Data were collected from 19 ethnically diverse veterans. Cognitive functioning in six domains (verbal learning, memory, attention, language, executive functioning, and information processing speed) was assessed. Results: The majority of veterans (57%) demonstrated CI on a measure of single trial list learning, 44% exhibited CI on short delay memory for lists, and 31% exhibited CI in long delay memory for lists. CI on measures of memory for stories (14%) and executive functioning (6%) were less common, and none of the participants demonstrated CI on measures of attention, language, or information processing speed. Conclusions: CI on measures of single trial list learning and memory for lists are common in older patients with PTSD evaluated in a memory disorders clinic and are likely to contribute to functional deficits. Copyright © 2011 John Wiley & Sons, Ltd.     

Neuropsychological Findings in Combat-Related Posttraumatic Stress Disorder

Previous research investigating whether combat-related Posttraumatic Stress Disorder (PTSD) is associated with impaired neuropsychological functioning has yielded inconsistent findings. The present study addressed many methodological limitations of previous research. Neuropsychological measures of intellectual ability, learning, memory, attention, visuospatial ability, executive functioning, language, and psychomotor speed were compared in four groups of early middle-aged community dwelling veterans. The four demographically comparable groups were: (a) those with current PTSD symptoms (n =80); (b) those with a prior history of PTSD but not currently experiencing active PTSD symptoms (n =80); (c) a non-PTSD psychiatrically matched control group (n =80); and (d) a normal control group (n =80). Results indicated that the four groups did not statistically differ on the neuropsychological measures and that veterans with PTSD perform similarly to demographically matched controls. Results further suggested that the cognitive difficulties previously linked to PTSD may actually have been secondary to preexisting individual differences or other clinical conditions coexisting with PTSD.     

Neuropsychological findings in combat-related posttraumatic stress disorder

Previous research investigating whether combat-related Posttraumatic Stress Disorder (PTSD) is associated with impaired neuropsychological functioning has yielded inconsistent findings. The present study addressed many methodological limitations of previous research. Neuropsychological measures of intellectual ability, learning, memory, attention, visuospatial ability, executive functioning, language, and psychomotor speed were compared in four groups of early middle-aged community dwelling veterans. The four demographically comparable groups were: (a) those with current PTSD symptoms (n=80); (b) those with a prior history of PTSD but not currently experiencing active PTSD symptoms (n=80); (c) a non-PTSD psychiatrically matched control group (n=80); and (d) a normal control group (n=80). Results indicated that the four groups did not statistically differ on the neuropsychological measures and that veterans with PTSD perform similarly to demographically matched controls. Results further suggested that the cognitive difficulties previously linked to PTSD may actually have been secondary to preexisting individual differences or other clinical conditions coexisting with PTSD.     

Problem alcohol use in veterans with mild traumatic brain injury: Associations with cognitive performance and psychiatric symptoms

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 with demographic or mTBI characteristics; and (c) examine the associations between alcohol use, mTBI history, psychiatric functioning, and cognition. Method: We assessed 59 veterans (n = 32 with mTBI history; n = 27 military controls) for problem alcohol use (Alcohol Use Disorders Identification Test: AUDIT), psychiatric symptoms, and neuropsychological functioning. Results: Compared to controls, veterans with mTBI history were more likely to score above the AUDIT cutoff score of 8 (p = .016), suggesting a higher rate of problem drinking. Participants with mTBI history also showed elevated psychiatric symptoms (ps < .001) and lower cognitive scores (ps < .05 to < .001). Veterans with higher AUDIT scores were younger (p = .05) and had less education (p < .01) and more psychiatric symptoms (ps < .01), but mTBI characteristics did not differ. After controlling for combat and mTBI history (R² = .04, ns) and posttraumatic stress disorder (PTSD) symptoms (ΔR² = .08, p = .05), we found that higher AUDIT scores were associated with poorer attention/processing speed, F(9, 37) = 2.55, p = .022; ΔR² = .26, p = .03. Conclusions: This preliminary study suggested that veterans with mTBI history may be at increased risk for problem drinking. Problem alcohol use was primarily associated with more severe PTSD symptoms and poorer attention/processing speed, though not with combat or mTBI characteristics per se. Importantly, findings emphasize the importance of assessing for and treating problematic alcohol use and comorbid psychiatric symptoms among veterans, including those with a history of neurotrauma.     

PTSD and Cognitive Functioning: Importance of Including Performance Validity Testing

Many studies have observed an association between post-traumatic stress disorder (PTSD) and cognitive deficits across several domains including memory, attention, and executive functioning. The inclusion of response bias measures in these studies, however, remains largely unaddressed. The purpose of this study was to identify possible cognitive impairments correlated with PTSD in returning OEF/OIF/OND veterans after excluding individuals failing a well-validated performance validity test. Participants included 126 men and 8 women with a history of mild traumatic brain injury (TBI) referred for a comprehensive neuropsychological evaluation as part of a consortium of five Veterans Affairs hospitals. The PTSD CheckList (PCL) and Word Memory Test (WMT) were used to establish symptoms of PTSD and invalid performance, respectively. Groups were categorized as follows: Control (PCL < 50, pass WMT), PTSD-pass (PCL ≥ 50, pass WMT), and PTSD-fail (PCL ≥ 50, fail WMT). As hypothesized, failure on the WMT was associated with significantly poorer performance on almost all cognitive tests administered; however, no significant differences were detected between individuals with and without PTSD symptoms after separating out veterans failing the WMT. These findings highlight the importance of assessing respondent validity in future research examining cognitive functioning in psychiatric illness and warrant further consideration of prior studies reporting PTSD-associated cognitive deficits.     

The contributions of self-reported injury characteristics and psychiatric symptoms to cognitive functioning in OEF/OIF veterans with mild traumatic brain injury

Mild traumatic brain injury (mTBI) affects a significant number of combat veterans returning from Operation Enduring Freedom/Operation Iraqi Freedom (OEF/OIF). Although resolution of mTBI symptoms is expected over time, some individuals continue to report lingering cognitive difficulties. This study examined the contributions of self-reported mTBI injury characteristics (e.g., loss of consciousness, post-traumatic amnesia) and psychiatric symptoms to both subjective and objective cognitive functioning in a sample of 167 OEF/OIF veterans seen in a TBI clinic. Injury characteristics were not associated with performance on neuropsychological tests but were variably related to subjective ratings of cognitive functioning. Psychiatric symptoms were highly prevalent and fully mediated most of the relationships between injury characteristics and cognitive ratings. This indicates that mTBI characteristics such as longer time since injury and loss of consciousness or post-traumatic amnesia can lead to increased perceived cognitive deficits despite having no objective effects on cognitive performance. Psychiatric symptoms were associated with both cognitive ratings and neuropsychological performance, illustrating the important role that psychiatric treatment can potentially play in optimizing functioning. Finally, subjective cognitive ratings were not predictive of neuropsychological performance once psychiatric functioning was statistically controlled, suggesting that neuropsychological assessment provides valuable information that cannot be gleaned from self-report alone.     

Executive deficits in chronic PTSD related to political violence

Twenty-two subjects with chronic PTSD were compared to 23 subjects with no diagnoses (NPD) on tests of executive functioning (EF) that are assumed to have clinical significance after exposure to political violence. METHOD: The three cognitive components of EF, intentionality, inhibition and executive memory [Burgess, P. W., Alderman, N., Evans, J., Emslie, H., Wilson, B. A. (1998). The ecological validity of tests of executive function. Journal of the International Neuropsychological Society, 4, 547-58], were measured using the Tower of London, Stroop Color-Word Test and Wisconsin Card Sorting Test (WCST), respectively. RESULTS: The PTSD group was impaired on tasks measuring automatic processing and executive memory. Executive memory problems were related to elevated posttraumatic symptoms, but the executive components intentionality and inhibition did not differentiate the groups. Arousal and intrusive symptoms had no impact on intentionality. CONCLUSION: Posttraumatic symptoms are related to automatic processing problems and impairment in executive memory. Observed dysfunctions in mental flexibility could have a negative impact on the cognitive processing of traumatic memory, thus preventing from recovery.     

Broad spectrum psychiatric comorbidity is associated with better executive functioning in an inpatient sample of individuals with schizophrenia

BackgroundIndividuals with schizophrenia exhibit cognitive deficits but whether these deficits are exacerbated by broad spectrum psychiatric comorbidity (i.e., comorbidity that is inclusive of disorders from different diagnostic categories) is unclear. A broad spectrum approach to psychiatric comorbidity is an ecologically valid way to capture the diagnostic heterogeneity inherent in psychiatric presentations.ObjectiveThis study compared the attention, working memory, processing speed, and executive functioning of individuals with schizophrenia only relative to individuals with schizophrenia and broad spectrum psychiatric comorbidity.MethodArchival patient neuropsychological test data were obtained for a sample of patients with schizophrenia only (n = 30) and a sample of patients with schizophrenia and psychiatric comorbidity (n = 33). Relevant tests were used to form composite indices for the cognitive domains of attention, working memory, speed of processing, and executive functioning.ResultsUnexpectedly, individuals with schizophrenia and psychiatric comorbidity had significantly better executive functioning than individuals with schizophrenia only. There were no other significant differences.ConclusionsA broad spectrum approach to psychiatric comorbidity can help to account for differences in the executive functioning of individuals with schizophrenia. In clinical settings, individuals with schizophrenia and psychiatric comorbidity may benefit from intervention strategies that capitalize on their relatively higher executive functioning.     

Apolipoprotein E (APOE) ε4 genotype is associated with reduced neuropsychological performance in military veterans with a history of mild traumatic brain injury

Introduction: The purpose of this study was to investigate the effect of the apolipoprotein E (APOE) ε4 allele on neuropsychological functioning in military Veterans with a remote history of mild traumatic brain injury (mTBI).

Method: This cross-sectional study included 99 Veterans (mTBI = 53; military controls, MC = 46) who underwent neuropsychological assessment and APOE genotyping. Three neurocognitive composite scores—memory (α = .84), speed (α = .85), and executive functioning (α = .76)—were computed from 24 norm-referenced variables, and the total number of impaired scores (>1.5 SDs below mean) for each participant was calculated.

Results: Analyses of covariance adjusting for ethnicity and posttraumatic stress disorder (PTSD) symptoms revealed that although no significant differences were observed between mTBI ε4 allele groups on the executive functioning composite (p > .05), mTBI ε4+ Veterans performed more poorly than ε4? Veterans on the memory (p = .045, η_p² = .083) and speed (p = .023, η_p² = .106) composites. Furthermore, Mann–Whitney U tests showed that ε4+ mTBI Veterans displayed a significantly greater number of impaired scores than did ε4? mTBI Veterans (p = .010, r = .355). In contrast, there were no significant differences across any of the cognitive variables between ε4+ and ε4? MCs (all p > .05).

Conclusions: Results suggest that APOE ε4 genotype is related to reduced memory and processingspeed performance, as well as overall cognitive impairment, in those with a history of mTBI, but does not appear to have the same negative effects on cognition in the absence of neurotrauma. Although results are preliminary, the present study advances understanding of genetic influences on cognitive functioning in Veterans with remote mTBIs. Future longitudinal work is needed to elucidate the underlying brain-based mechanisms of ε4 allelic effects on cognitive and clinical outcomes following TBI.     

Impaired response inhibition in veterans with post-traumatic stress disorder and mild traumatic brain injury

Combat veterans with post-traumatic stress disorder (PTSD) can show impairments in executive control and increases in impulsivity. The current study examined the effects of PTSD on motor response inhibition, a key cognitive control function. A Go/NoGo task was administered to veterans with a diagnosis of PTSD based on semi-structured clinical interview using DSM-IV criteria (n = 40) and age-matched control veterans (n = 33). Participants also completed questionnaires to assess self-reported levels of PTSD and depressive symptoms. Performance measures from the patients (error rates and reaction times) were compared to those from controls. PTSD patients showed a significant deficit in response inhibition, committing more errors on NoGo trials than controls. Higher levels of PTSD and depressive symptoms were associated with higher error rates. Of the three symptom clusters, re-experiencing was the strongest predictor of performance. Because the co-morbidity of mild traumatic brain injury (mTBI) and PTSD was high in this population, secondary analyses compared veterans with PTSD+mTBI (n = 30) to veterans with PTSD only (n = 10). Although preliminary, results indicated the two patient groups did not differ on any measure (p > .88). Since cognitive impairments could hinder the effectiveness of standard PTSD therapies, incorporating treatments that strengthen executive functions might be considered in the future. (JINS, 2012, 18, 1-10).     

Executive function and memory in posttraumatic stress disorder: a study of Bosnian war veterans.

The present study assessed neuropsychological functions related to attention, executive function and everyday memory in a group of men with a diagnosis of combat-related posttraumatic stress disorder (PTSD). Twenty Bosnian male combat veterans with a diagnosis of PTSD were tested using the Sustained Attention to Response Task, the Hayling Sentence Completion Test, the Trail Making Test, Rivermead Behavioral Memory Test and Wechsler Adult Intelligence Scale (verbal scales). Their performance was compared with age- and IQ-matched male war veterans with no PTSD. The study disclosed pervasive cognitive impairments with large effect sizes pertaining to attention, working memory, executive function, and memory. The effects did not appear to be attributable to alcohol abuse, loss of consciousness, or educational level. We speculate that, in the present group of combat veterans, PTSD was associated with dysfunction of a higher-level attentional resource which in turn affected the activity in other systems concerned with memory and thought.     

Elevated rates of memory impairment in military service-members and veterans with posttraumatic stress disorder

Introduction: Studies investigating the neurocognitive effects of posttraumatic stress disorder (PTSD) routinely find “deficits” in various cognitive domains. However, the rate of cognitive impairment in individuals with PTSD remains unclear, as studies have focused on null hypothesis testing (NHT) and inferring patterns of impairment rather than empirically determining the rate of cognitive impairment in this sample. Method: This study examined rates of cognitive impairment using a domain-specific approach in non-treatment-seeking Operation Enduring Freedom/Operation Iraqi Freedom/Operation New Dawn service members and veterans with (n = 92) and without (n = 79) PTSD and without substance abuse/dependence who passed a performance validity measure and were matched on age, education, estimated IQ, and ethnicity. Chi-square analyses were used to compare the rate of cognitive impairment across groups based on normative scores using three cutoffs (?1, ?1.5, and ?2 SDs). NHT was also used to compare performances across groups. Results: Individuals with PTSD showed higher rates of impairment in memory (?1-SD cutoff) than controls, but equivalent rates of impairment in attention, processing speed, and executive functioning; no significant differences were found on NHT. Impairment in any domain was also more prevalent in PTSD (?1-, ?1.5-, and ?2-SD cutoffs). No differences were found on NHT or rates of impairment in individuals with PTSD with (n = 34) and without (n = 58) depression. Conclusions: Patients with PTSD were more likely to meet criteria for memory impairment and to show impairment in any domain than controls. Patients with PTSD and comorbid depression were no more likely to be impaired in any cognitive domain or to have lower scores on individual cognitive tasks than patients with PTSD alone. Clinicians noting cognitive impairment in individuals with PTSD should exercise caution before ascribing that impairment to another etiology if deficits are limited to memory.     

A meta-analysis of cognitive functioning in older adults with PTSD

A meta-analysis was conducted to summarize and integrate the literature on the cognitive functioning of older adults with posttraumatic stress disorder (PTSD). We hypothesized that those with PTSD would exhibit worse performance in each of the cognitive domains studied when compared to older adults without PTSD. Major databases were queried and eleven articles met criteria for review. As predicted, there was evidence of worse performance across cognitive measures in older adult samples with PTSD relative to older samples without PTSD. The strongest effect across samples was found for lower test scores in the broad domain of memory among older adults with PTSD, and there was evidence that trauma exposure is uniquely associated with worse performance on tests specific to learning. We outline factors thought to contribute to the interactions among PTSD, cognitive deficits, and the aging process. These findings highlight the need for thorough evaluation of cognitive functioning in older adults with PTSD, particularly in the areas of processing speed, learning, memory, and executive functioning.     

Neuropsychological function in children with maltreatment-related posttraumatic stress disorder

OBJECTIVE: Studies in adults have reported changes in concentration, learning, and memory in individuals with posttraumatic stress disorder (PTSD). However, there are few studies of cognitive function in children with PTSD. The goal of the current study was to evaluate cognition in children with PTSD. METHOD: The cognitive status of 14 pediatric psychiatric outpatients with maltreatment-related PTSD and 15 sociodemographically similar children who were healthy and had not been maltreated was examined. Neuropsychological instruments measured language, attention, abstract reasoning/executive function, learning and memory, visual-spatial processing, and psychomotor function. RESULTS: The children with PTSD performed more poorly on measures of attention and abstract reasoning/executive function. CONCLUSIONS: Although based on a small number of subjects, these results support cognitive differences between children with and without maltreatment-related PTSD.     

Enhancing Access to Psychiatric Care for Posttraumatic Stress Disorder in Veterans with Mild Traumatic Brain Injury through Integrated Services

(i) To describe an integrated model of psychiatric care for the treatment of posttraumatic stress disorder (PTSD) in veterans with mild traumatic brain injury (mTBI). (ii) To evaluate access to and engagement in psychiatric care among veterans with comorbid PTSD and mTBI after implementation of an Integrated Care (IC) model compared to the previous Usual Care (UC). 100 randomly selected charts, 50 from each of UC and IC were reviewed in this non-concurrent case- control study. Polytrauma Network Site (PNS), an outpatient rehabilitation clinic, for veterans who suffered from brain and other traumatic injuries at an urban VA Polytrauma Rehabilitation Center. Veterans receiving treatment for mTBI symptoms by the rehabilitation team were referred for medication management for PTSD to UC and IC. Co-located access to psychiatric care for medication management as part of the interdisciplinary team with the goal of expediting rehabilitation and functional recovery. Number of consults for psychiatric care for medication management scheduled and completed within 30 days, and number of veterans offered, initiating, and completing evidence-based psychotherapies for PTSD in UC compared to IC. After implementation of IC there were significant improvements in timely completion of consults and patient engagement with a psychiatrist. There also were improvements in number of referrals, initiation, and completion of evidence-based psychotherapies for the treatment of PTSD. IC within the PNS shows promise as an effective care model for increasing access and engagement in care for veterans with comorbid PTSD/mTBI. Future research is needed to examine the utility of this model in other sites.

     

Cognitive changes in asymptomatic carriers of the Huntington disease mutation gene

Huntington disease (HD) is a neurodegenerative disorder due to an excessive number of CAG repeats in the IT15 gene on chromosome 4. Studies of cognitive function in asymptomatic gene carriers have yielded contradictory results. This study compared cognitive performance in 44 subjects with the HD mutation (group of carriers) who had no clinical signs of HD and 39 at-risk individuals without HD mutation (group of non-carriers). Neuropsychological evaluation focused on global cognitive efficiency, psychomotor speed, attentional, executive and memory functions. Significant differences, with lower performances in the group of gene carriers, were detected for some measures of psychomotor speed, attention and executive functioning (all P  < 0.01). More differences between groups were observed for memory measures, in particular on the California Verbal Memory Test. Complementing these observations, cognitive scores were correlated with age in the group of gene carriers, but not in the group of non-carriers. This suggests that the cognitive changes precede the appearance of the motor and psychiatric symptoms in HD and that tests proved to be sensitive to early HD deficiencies are better suited than global cognitive efficiency scales to observe them.     

Neurocognitive Functioning and Subtypes of Child Molesters: Poorer Working Memory Differentiates Incestuous from Non-Incestuous Offenders

Studies of neurocognitive functioning suggest that child molesters can be differentiated into offender types based on frontal neurocognitive (executive) functioning. The aim of this study was to examine performance on cognitive tests that assess processing speed, cognitive flexibility, executive control and working memory in two samples of child molesters (incestuous and non-incestuous) compared with an age- and education-matched control group of non-offenders. These groups were matched for clinical, sociodemographic and criminological characteristics. Our results suggest that cognitive measures of executive functioning (i.e., processing speed, cognitive flexibility and executive control) differentiate child molesters from non-offender participants, and that working memory performance in incestuous child molesters differentiates this group from non-incestuous offenders and control participants. These findings suggest specific components of impaired cognitive performance in incestuous child molesters relative to extra-familial offenders and non-offender control participants. Poorer working memory in incestuous child molesters may help differentiate this group from other child molester types.     

Fatigue – but not mTBI history,PTSD, or sleep quality – directly contributes to reduced prospective memory performance in Iraq and Afghanistan era Veterans

Abstract

Objective: Memory problems that affect daily functioning are a frequent complaint among Veterans reporting a history of repetitive mild traumatic brain injury (mTBI), especially in cohorts with comorbid PTSD. Here, we test the degree to which subjective sleep impairment and daytime fatigue account for the association of PTSD and self-reported mTBI history with prospective memory. Method: 82 Veterans with and without personal history of repeated blast-related mTBI during deployment were administered the Clinician Administered PTSD Scale (CAPS), Memory for Intentions Test (MIST), Patient Health Questionnaire-9 (PHQ-9), Neurobehavioral Symptom Inventory (NSI), and the Pittsburgh Sleep Quality Index (PSQI). Relationships between self-reported mTBI, PTSD, self-reported poor sleep and daytime fatigue, and MIST performance were modeled using partial least squares structural equation modeling (PLS-SEM). Results: Reported daytime fatigue was strongly associated with poorer prospective memory performance. Poor subjective sleep quality was strongly and positively associated with reported daytime fatigue, but had no significant direct effect on prospective memory performance. PTSD diagnosis and self-reported mTBI history were only associated with prospective memory via their impact on subjective sleep quality and daytime fatigue. Conclusions: Results suggest that daytime fatigue may be a mediating factor by which both mTBI and PTSD can interfere with prospective memory. Additional attention should be given to complaints of daytime fatigue, independent of subjective sleep quality, in the clinical care of those with a self-reported history of mTBI, and/or PTSD. Further research into whether interventions that decrease daytime fatigue lead to improvement in prospective memory and subjective cognitive functioning is warranted.     

Homelessness and neuropsychological impairment: preliminary analysis of adults entering outpatient psychiatric treatment

Homelessness has been associated with neuropsychological (NP) impairment, but few studies have adequately controlled for factors known to affect NP performance. We performed brief NP testing examining learning, recall, processing speed, executive functioning, and verbal fluency in 50 ever- and 22 never-homeless persons entering outpatient psychiatric treatment. Groups were matched a priori on key demographic, substance use, psychiatric, and premorbid intelligence quotient characteristics. Rates of NP impairment were high among both groups (46%-54%). There were no significant differences in global NP impairment. There were trends toward better levels of processing speed and executive functioning among never-homeless relative to ever-homeless. Among the ever-homeless group, NP test performance was unrelated to number of homelessness episodes (median 3). Findings confirm high prevalence of NP impairment among homeless individuals but provide little evidence for broad NP differences between ever- and never-homeless persons matched for coexisting conditions that have confounded interpretation of previous results in the literature.