Association of MOS-Based Blast Exposure With Medical Outcomes

The study of effects associated with human exposure to repeated low-level blast during training or operations of select military occupational specialties (MOS) challenges medical science because acute negative effects that might follow such exposures cannot be expected to be clear or prevalent. Any gross effects from such occupational blast exposure on health or performance should be expected to have been already identified and addressed by affected military units through changes to their standard training protocols. Instead, effects, if any, should be expected to be incremental in nature and to vary among individuals of different susceptibilities and exposure histories. Despite the challenge, occupational blast-associated effects in humans are emerging in ongoing research. The purpose of the present study was to examine medical records for evidence of blast-associated effects that may have clinical significance in current standard of care. We hypothesized that populations exposed to blast by virtue of their military occupation would have poorer global medical outcomes than cohorts less likely to have been occupationally exposed. Records from a population of 50,254 service members in MOSs with a high likelihood of occupational blast exposure were compared to records from a matched cohort of 50,254 service members in MOSs with a lower likelihood of occupational blast exposure. These two groups were compared in hospitalizations, outpatient visits, pharmacy, and disability ratings. The clearest finding was higher risk among blast-exposed MOSs for ambulatory encounters for tinnitus, with adjusted risk ratios of 1.19 (CI 1.03–1.37), 1.21 (CI 1.16–1.26), and 1.31 (CI 1.18–1.45) across career time points. Other hypothesized effects (i.e., neurological outcomes) were smaller and were associated with acute exposure. This study documents that service members in occupations that likely include repeated exposure to blast are at some increased risk for neurosensory conditions that present in medical evaluations. Other hypothesized risks from occupational exposure may manifest as symptomology not visible in the medical system or current standard of care. Separate studies, observational and epidemiological, are underway to evaluate further the potential for occupational risk, but the evidence presented here may indicate near-term opportunities to guide efforts to reduce neurosensory risk among exposed service members.

Towards a blood-based diagnostic panel for bipolar disorder

BACKGROUND

Bipolar disorder (BD) is a costly, devastating and life shortening mental disorder that is often misdiagnosed, especially on initial presentation. Misdiagnosis frequently results in ineffective treatment. We investigated the utility of a biomarker panel as a diagnostic test for BD.

METHODS AND FINDINGS

We performed a meta-analysis of eight case-control studies to define a diagnostic biomarker panel for BD. After validating the panel on established BD patients, we applied it to undiagnosed BD patients. We analysed 249 BD, 122 pre-diagnostic BD, 75 pre-diagnostic schizophrenia and 90 first onset major depression disorder (MDD) patients and 371 controls. The biomarker panel was identified using ten-fold cross-validation with lasso regression applied to the 87 analytes available across the meta-analysis studies. We identified 20 protein analytes with excellent predictive performance [area under the curve (AUC)⩾0.90]. Importantly, the panel had a good predictive performance (AUC 0.84) to differentiate 12 misdiagnosed BD patients from 90 first onset MDD patients, and a fair to good predictive performance (AUC 0.79) to differentiate between 110 pre-diagnostic BD patients and 184 controls. We also demonstrated the disease specificity of the panel.

CONCLUSIONS

An early and accurate diagnosis has the potential to delay or even prevent the onset of BD. This study demonstrates the potential utility of a biomarker panel as a diagnostic test for BD.

Association between antibodies to multiple infectious and food antigens and new onset schizophrenia among US military personnel

INTRODUCTION

Multiple studies have documented immune activation in many individuals with schizophrenia suggesting that antigens capable of generating a prolonged immune response may be important environmental factors in many cases of this disorder. While existing studies have found single-agent associations of antibodies to food and neurotropic infectious agents with schizophrenia, a simultaneous examination of multiple agents may shed light on agent interactions or possible etiopathogenic pathways.

METHODS

We used traditional regression and novel statistical techniques to examine associations of single and combined infectious and food antigens with schizophrenia. We tested 6106 serum samples from 855 cases and 1165 matched controls.

RESULTS

Higher antibody levels to casein were borderline significant in the prediction of schizophrenia (HR=1.08, p=0.06). Study participants with higher cytomegalovirus (CMV) IgG antibody levels had a reduced risk of developing schizophrenia (HR=0.90; p=0.02). While IgG antibodies to gliadin, Toxoplasma gondii, vaccinia, measles, and human herpesvirus-6 (HHV-6) showed no significant independent associations with schizophrenia, the increase in antibody levels to several combinations of agents, to include casein, measles, CMV, T. gondii and vaccinia, was predictive of an 18-34% increase in the risk of developing schizophrenia.

CONCLUSION

Certain patterns of antibodies, involving some agents, were predictive of developing schizophrenia, with the magnitude of association rising when the level of antibodies increased to two or more agents. A heightened antibody response to a combination of several infectious/food antigens might be an indicator of an altered immune response to antigenic stimuli.

Descriptive epidemiology and underlying psychiatric disorders among hospitalizations with self-directed violence

Background

Suicide claims over one million lives worldwide each year. In the United States, 1 per 10,000 persons dies from suicide every year, and these rates have remained relatively constant over the last 20 years. There are nearly 25 suicide attempts for each suicide, and previous self-directed violence is a strong predictor of death from suicide. While many studies have focused on suicides, the epidemiology of non-fatal self-directed violence is not well-defined.

Objective

We used a nationally representative survey to examine demographics and underlying psychiatric disorders in United States (US) hospitalizations with non-fatal self-directed violence (SDV).

Method

International Classification of Disease, 9^th Revision (ICD-9) discharge diagnosis data from the National Hospital Discharge Survey (NHDS) were examined from 1997 to 2006 using frequency measures and adjusted logistic regression.

Results

The rate of discharges with SDV remained relatively stable over the study time period with 4.5 to 5.7 hospitalizations per 10,000 persons per year. Excess SDV was documented for females, adolescents, whites, and those from the Midwest or West. While females had a higher likelihood of self-poisoning, both genders had comparable proportions of hospitalizations with SDV resulting in injury. Over 86% of the records listing SDV also included psychiatric disorders, with the most frequent being affective (57.8%) and substance abuse (37.1%) disorders. The association between psychiatric disorders and self-injury was strongest for personality disorders for both males (OR = 2.1; 95% CI = 1.3–3.4) and females (OR = 3.8; 95% CI = 2.7–5.3).

Conclusion

The NHDS provides new insights into the demographics and psychiatric morbidity of those hospitalized with SDV. Classification of SDV as self-injury or self-poisoning provides an additional parameter useful to epidemiologic studies.

Identification of a blood-based biological signature in subjects with psychiatric disorders prior to clinical manifestation

OBJECTIVES

To determine whether a molecular signature is present in blood of patients with psychiatric disorders before manifestation of symptoms.

METHODS

Multiplex immunoassay analyses were carried out using serum obtained from two case-control studies of schizophrenia (n = 75) and bipolar disorder (n = 110) patients and their matched controls. The samples were drawn within 1 month before estimated onset of illness.

RESULTS

This led to identification of 20 molecules which were altered in pre-schizophrenia and 14 molecules in pre-bipolar disorder subjects compared to controls. Only two of these molecular changes were identical in both data sets and predictive testing confirmed that the biomarker signatures for pre-schizophrenia and pre-bipolar disorder were dissimilar.

CONCLUSION

The present results suggest that there are distinct serum alterations that occur before clinical manifestation of schizophrenia and bipolar disorder. These findings could lead to development of diagnostic tests to help clinical psychiatrists identify and classify vulnerable patients early in the disease process, allowing for earlier and more effective therapeutic intervention.

Psychiatric and general medical conditions comorbid with bipolar disorder in the National Hospital Discharge Survey

OBJECTIVE

From 40% to 65% of patients with bipolar disorder are estimated to have diagnoses of one or more comorbid conditions. The purpose of this study was to identify comorbid disorders and compare their prevalence in hospitalizations of persons with or without bipolar disorder.

METHODS

Data from the 1979-2006 National Hospital Discharge Survey (NHDS) were analyzed to examine temporal trends in the proportional morbidity of bipolar disorder, demographic characteristics, and the most frequent comorbid conditions in hospitalizations of patients with or without bipolar disorder. Among discharges of patients ages 13-64, the conditions of those with a primary diagnosis of bipolar disorder (N=27,054) were compared with those with other primary diagnoses (N=2,325,247). Proportional morbidity ratios (PMRs) were calculated.

RESULTS

There was an average 10% (p<.001) increase per year in the proportion of discharges with bipolar disorder. Proportions of discharge records that noted bipolar disorder were higher among females and whites and were highest among persons ages 13-19 and those from the Northeast. Discharge records noting a primary diagnosis of bipolar disorder showed higher proportions of most psychiatric and some general medical conditions, including acquired hypothyroidism (proportional morbidity ratio=2.6), viral hepatitis (1.6), obesity (1.4), and various diseases of the skin and subcutaneous tissue (range 2.6-4.2) and of the nervous (1.4-3.8), respiratory (1.4-2.3), and musculoskeletal (1.2-1.9) systems.

CONCLUSIONS

Patients with bipolar disorder have an increased illness burden from many psychiatric and general medical conditions. Knowledge of the most prevalent comorbid conditions and methods for their prevention, early diagnosis, and treatment are critical in improving the prognosis of patients with bipolar disorder.

Association between bovine casein antibody and new onset schizophrenia among US military personnel

Schizophrenia is a pervasive neuropsychiatric disorder of uncertain etiology. Multiple studies have documented immune activation in individuals with schizophrenia. One antigen capable of inducing a prolonged immune response is bovine casein derived from ingested milk products. Increased levels of casein antibodies have been found in individuals with schizophrenia after diagnosis. This study was directed at determining the potential association between schizophrenia and pre-illness onset levels of immunoglobulin G (IgG) antibodies to bovine casein. Parallel analyses for casein antibody levels with bipolar disorder were included as comparison. Cases were service members who received medical discharges from the military with a schizophrenia diagnosis from 1992 to 2005. Serum specimens were selected for 855 cases and 1165 matched healthy controls. IgG antibodies to bovine whole-casein were measured by solid phase enzyme-linked immunosorbent assays (ELISAs). Hazard ratios (HR) were calculated to examine the associations of casein IgG level with risk of schizophrenia by time to diagnosis and by subjects' initial level. Increasing casein IgG antibody levels among those with a high initial level, drawn before diagnosis, was associated with an 18% increase in the hazard risk of schizophrenia per unit increase (value of low-positive standard) in IgG antibody levels (HR=1.18; 95% CI 1.04, 1.34). This is the first report to identify an association between the risk of schizophrenia and elevated antibodies to bovine casein prior to disease onset. Additional research is required to elucidate the complex genetic environmental interactions involved in the pathogenesis of schizophrenia and to identify potentially modifiable risk factors.

Incidence of adult onset schizophrenic disorders in the US military: patterns by sex, race and age

BACKGROUND

There are limited data describing the epidemiology of adult-onset schizophrenic disorders in the United States. Although the military is not proportionately comparable in all demographic characteristics to the civilian population, it is drawn from all racial/ethnic subgroups, and members range in age from 17 to >60 years. We describe the incidence of hospitalization for new onset schizophrenic disorders among military members by sex, race, and age.

METHODS

Using military inpatient data, we evaluated patterns of initial hospitalizations for schizophrenic disorders among military personnel for 2000-2009, focusing on sex, race, and age. No individual-level data were available.

RESULTS

From 2000-2009, 1976 military personnel had a first schizophrenic disorder hospitalization, with an overall incidence rate of 0.14/1000 person-years. There were no consistent changes in rates over time. While overall incidence rates were similar for men and women (incidence rate ratio (IRR)=1.10), rates were higher among men than women below age 25; after 25-30 rates were higher among women. Incidence was higher among blacks and other racial groups, with IRR=2.0 and 1.3, respectively.

CONCLUSION

Medical screening of military applicants prevents persons with overt or a reported history of psychosis, and most with serious behavior problems, from enlisting; therefore, first hospitalization is likely to reflect new illness. No pre-military socioeconomic data were available, however, essentially all study subjects were high school graduates; unmeasured differences in socioeconomic status were unlikely to explain the observed results. This report may provide lower bound estimates of the schizophrenic disorder incidence in the United States.

Descriptive epidemiology of bipolar I disorder among United States military personnel

Psychiatric disorders in military members require substantial medical, administrative, and financial resources, and are among the leading causes of hospitalization and early discharge. We reviewed available data to better understand the incidence of bipolar I disorder among military personnel. Defense Medical Epidemiology Database inpatient data were used. Descriptive and comparative statistics were performed. From 1997-2006 there were 3,317 first hospitalizations for bipolar I disorder with a mean of 1.2 hospitalizations per case. The rate of first occurrence among this adult population was 0.24 per 1,000 person-years. The incidence increased over time for depressed and mixed episode types among both genders. High risk groups include women, younger individuals, and whites. This population provides insight into adult onset bipolar I disorder incidence and demographic patterns not available elsewhere and offers potential opportunities to improve its understanding.

Psychiatric and general medical conditions comorbid with schizophrenia in the National Hospital Discharge Survey

OBJECTIVE

Morbidity and mortality from general medical conditions are elevated among patients with schizophrenia compared with the general U.S. population. More than 50% of patients with schizophrenia have one or more comorbid psychiatric or general medical conditions. This study determined types of comorbid disorders and their prevalence among hospitalized patients with and without schizophrenia.

METHODS

Data from the National Hospital Discharge Survey, a nationally representative sample, were analyzed for 1979-2003 (N=5,733,781 discharges). For discharges of patients aged 15 to 64 with at least one comorbid condition, the conditions of those with a primary diagnosis of schizophrenia (N=26,279) were compared with those with other primary diagnoses (N=1,936,876). Proportional morbidity ratios (PMRs) were calculated.

RESULTS

The proportion of discharges listing schizophrenia, particularly schizoaffective disorder, increased significantly over time among both males and females. The proportion was higher among males, blacks, and discharges in the Northeast. Discharge records with a primary diagnosis of schizophrenia showed higher proportions of all comorbid psychiatric conditions examined and of some general medical conditions, including acquired hypothyroidism (PMR=2.9), contact dermatitis and other eczema (PMR=2.9), obesity (PMR=2.0), epilepsy (PMR=2.0), viral hepatitis (PMR=1.4), diabetes type II (PMR=1.2), essential hypertension (PMR=1.2), and various chronic obstructive pulmonary diseases (PMR range 1.2-1.5).

CONCLUSIONS

Knowledge of the risks of comorbid psychiatric and general medical conditions is critical both for clinicians and for patients with schizophrenia. Closer attention to prevention, early diagnosis, and treatment of comorbid conditions may decrease associated morbidity and mortality and improve prognosis among patients with schizophrenia.

Results from a hypothesis generating case-control study: herpes family viruses and schizophrenia among military personnel

BACKGROUND

Herpes family viruses can cause central nervous system inflammatory changes that can present with symptoms indistinguishable from schizophrenia and therefore are of interest in schizophrenia research. Most existing studies of herpes viruses have used small populations and postdiagnosis specimens. As part of a larger research program, we conducted a hypothesis-generating case-control study of selected herpes virus antibodies among individuals discharged from the US military with schizophrenia and pre- and postdiagnosis sera.

METHODS

Cases (n = 180) were servicemembers hospitalized and discharged from military service with schizophrenia. Controls, 3:1 matched on several factors, were members not discharged. The military routinely collects and stores members' serum specimens. We used microplate enzyme immunoassay to measure immunoglobulin G (IgG) antibody levels to 6 herpes viruses in pre- and postdiagnosis specimens. Conditional logistic regression was used, and the measure of association was the hazard ratio (HR).

RESULTS

Overall, we found a significant association between human herpes virus type 6 and schizophrenia, with an HR of 1.17 (95% confidence interval [CI] = 1.04, 1.32). Women and blacks had significant negative associations with herpes simplex virus type 2 and cytomegalovirus; among blacks, there was a significant positive association with herpes simplex virus type 1. Among men, there was a HHV-6 temporal effect with an HR of 1.41 (95% CI = 1.02, 1.96) for sera drawn 6-12 months before diagnosis.

DISCUSSION

Findings from previous studies of herpes family viruses and schizophrenia have been inconsistent. Our study is based on a larger population than most previous studies and used serum specimens collected before onset of illness. This study adds to the body of knowledge and provides testable hypotheses for follow-on studies.

Evaluation of data obtained from military disability medical administrative databases for service members with schizophrenia or bipolar disorder

OBJECTIVE

We are studying associations between selected biomarkers and schizophrenia or bipolar disorder among military personnel. To assess potential diagnostic misclassification and to estimate the date of illness onset, we reviewed medical records for a subset of cases.

METHODS

Two psychiatrists independently reviewed 182 service medical records retrieved from the Department of Veterans Affairs. Data were evaluated for diagnostic concordance between database diagnoses and reviewers. Interreviewer variability was measured by using proportion of agreement and the kappa statistic. Data were abstracted to estimate date of onset.

RESULTS

High levels of agreement existed between database diagnoses and reviewers (proportion, 94.7%; kappa = 0.88) and between reviewers (proportion, 92.3%; kappa = 0.87). The median time between illness onset and initiation of medical discharge was 1.6 and 1.1 years for schizophrenia and bipolar disorder, respectively.

CONCLUSIONS

High levels of agreement between investigators and database diagnoses indicate that diagnostic misclassification is unlikely. Discharge procedure initiation date provides a suitable surrogate for disease onset.

Selected infectious agents and risk of schizophrenia among U.S. military personnel

OBJECTIVE

A number of studies have reported associations between Toxoplasma gondii (T. gondii) infection and the risk of schizophrenia. Most existing studies have used small populations and postdiagnosis specimens. As part of a larger research program, the authors conducted a hypothesis-generating case control study of T. gondii antibodies among individuals discharged from the U.S. military with a diagnosis of schizophrenia and serum specimens available from both before and after diagnosis.

METHOD

The patients (N=180) were military members who had been hospitalized and discharged from military service with a diagnosis of schizophrenia. Healthy comparison subjects (3:1 matched on several factors) were members of the military who were not discharged. The U.S. military routinely collects and stores serum specimens of military service members. The authors used microplate-enzyme immunoassay to measure immunoglobulin G (IgG) antibody levels to T. gondii, six herpes viruses, and influenza A and B viruses and immunoglobulin M (IgM) antibody levels to T. gondii in pre- and postdiagnosis serum specimens.

RESULTS

A significant positive association between the T. gondii IgG antibody and schizophrenia was found; the overall hazard ratio was 1.24. The association between IgG and schizophrenia varied by the time between the serum specimen collection and onset of illness.

CONCLUSION

The authors found significant associations between increased levels of scaled T. gondii IgG antibodies and schizophrenia for antibodies measured both prior to and after diagnosis.

Pezizalean mycorrhizas and sporocarps in ponderosa pine (Pinus ponderosa) after prescribed fires in eastern Oregon, USA

Post-fire Pezizales fruit commonly in many forest types after fire. The objectives of this study were to determine which Pezizales appeared as sporocarps after a prescribed fire in the Blue Mountains of eastern Oregon, and whether species of Pezizales formed mycorrhizas on ponderosa pine, whether or not they were detected from sporocarps. Forty-two sporocarp collections in five genera (Anthracobia, Morchella, Peziza, Scutellinia, Tricharina) of post-fire Pezizales produced ten restriction fragment length polymorphism (RFLP) types. We found no root tips colonized by species of post-fire Pezizales fruiting at our site. However, 15% (6/39) of the RFLP types obtained from mycorrhizal roots within 32 soil cores were ascomycetes. Phylogenetic analyses of the 18S nuclear ribosomal DNA gene indicated that four of the six RFLP types clustered with two genera of the Pezizales, Wilcoxina and Geopora. Subsequent analyses indicated that two of these mycobionts were probably Wilcoxina rehmii, one Geopora cooperi, and one Geopora sp. The identities of two types were not successfully determined with PCR-based methods. Results contribute knowledge about the above- and below-ground ascomycete community in a ponderosa pine forest after a low intensity fire.

Endemic human plague in New Mexico: risk factors associated with infection

A retrospective case-control study was conducted to identify risk factors, other than contact with infected animal tissues, for infection caused by Yersinia pestis in non-Indian residents of areas with endemic sylvatic plague in New Mexico. The study group consisted of 16 persons who had bacteriologically confirmed cases of plague in the period 1975-1976 and 45 controls who were matched by age, sex, and location of residence. Participants were questioned about outdoor activities, environmental conditions in and around the home, procedures of pet care, exposure to animals and insects, and medical history. The availability of harborage and food sources for wild rodents as a result of human activity in the immediate home environment was associated with risk of infection. Failure to take steps to control fleas on dogs and cats also appeared to be a possible risk factor. No other significant differences were found between patients and controls. Plague in New Mexico appears to result primarily from entry of the reservoir host into the habitat of the human rather than from entry of the human into the sylvatic habitat of the reservoir host.

Epidemiologic and clinical features of an outbreak of bubonic plague in New Mexico

An outbreak of seven cases of bubonic plague in New Mexico was investigated. Clinical features were studied and correlated with field studies in an attmept to determine the source of infection in patients with indefinite histories of exposure. Most patients presented with fever, malaise, and an acute painful lymphadenitis (bubo). One death occurred in a patient with bubonic-septicemic plague complicated by meningitis due to Yersinia pestis. All patients lived in rural or semirural areas, and most had been in the general vicinity of their usual residence during the six days prior to onset of symptoms. The outbreak was associated with probable epizootics in rodents in two different areas of the state. One case was traced to direct hand contact with plague-infected rabbits. One patient developed insect bites after sleeping in the same bed with a flea-infested cat. Three of the other five patients had insect bites, presumably flea bites, but none of the five recalled contact with rodents or rabbits. Four of the five, however, had been in contact with dogs or cats that were later shown to have titers of antibody to Y. pestis. These findings provide further support for the hypothesis that contact with domestic dogs and cats may result in direct or indirect transmission of Y. pestis to humans.

Bubonic plague from direct exposure to a naturally infected wild coyote

An 11-year-old boy developed axillary bubonic plague and plague meningitis 3 days after skinning a dead coyote near Albuquerque, New Mexico. The coyoto carcass was recovered 10 days later, and Yersinia pestis was isolated from spleen and marrow of the animal. This is the first report of human plague from exposure to a coyote. A review of experimental and epidemiologic studies suggests that severe plague infection in members of the family Canidae is unusual, and that the risk of acquiring plague from direct contact with coyote tissues is minimal. Nevertheless, certain precautions are outlined for persons working with wild coyotes.

Bubonic plague from exposure to a rabbit: a documented case, and a review of rabbit-associated plague cases in the United States

A 62-year-old woman developed bubonic plague with an epitrochlear bubo one to two days after skinning two cottontail rabbits. The implicated rabbits were later recovered from the patient's freezer, and Yersinia pestis was isolated from marrows of both rabbits. Although human plague cases in the United States have occasionally been traced to exposure to wild rabbits, this is the first documentation of plague infection in the actual rabbits to which the patient was exposed. All reported cases of rabbit-associated plague in the United States were then reviewed. Eight cases were characterized by direct exposure to rabbit tissues. Seven of the eight cases occurred in adult males who had hunted rabbits during winter months in plague-endemic areas. These patients had upper extremity buboes, and the case-fatality ration for the group was 50%. Three other cases in which rabbit exposure was indirect or its role less clear, were also analyzed.