Long-term follow-up of psychological distress, social functioning, and coping style in treated and untreated patients with solvent-induced chronic toxic encephalopathy

Chronic solvent-induced encephalopathy: course and prognostic factors of neuropsychological functioning

PURPOSE

Working in conditions with daily exposure to organic solvents for many years can result in a disease known as chronic solvent-induced encephalopathy (CSE). The aims for this study were to describe the neuropsychological course of CSE after first diagnosis and to detect prognostic factors for neuropsychological impairment after diagnosis.

METHODS

This prospective study follows a Dutch cohort of CSE patients who were first diagnosed between 2001 and 2011 and underwent a second neuropsychological assessment 1.5-2 years later. Cognitive subdomains were assessed and an overall cognitive impairment score was calculated. Paired t tests and multivariate linear regression analyses were performed to describe the neuropsychological course and to obtain prognostic factors for the neuropsychological functioning at follow-up.

RESULTS

There was a significant improvement on neuropsychological subdomains at follow-up, with effect sizes between small and medium (Cohen's d 0.27-0.54) and a significant overall improvement of neuropsychological impairment with a medium effect size (Cohen's d 0.56). Prognostic variables for more neuropsychological impairment at follow-up were a higher level of neuropsychological impairment at diagnosis and having a comorbid diagnosis of a psychiatric disorder at diagnosis.

CONCLUSIONS

Results are in line with previous research on the course of CSE, stating that CSE is a non-progressive disease after cessation of exposure. However, during follow-up the percentage patients with permanent work disability pension increased from 14 to 37%. Preventive action is needed in countries where exposure to organic solvents is still high to prevent new cases of CSE.

The Coping with Attention and Memory Complaints Questionnaire (CAMQ): psychometric evaluation of an instrument in suspected chronic solvent-induced encephalopathy (CSE)

Long-term occupational exposure to organic solvents may induce chronic solvent-induced encephalopathy (CSE), leading to neuropsychological impairments. We developed the Coping with Attention and Memory Complaints Questionnaire (CAMQ), an instrument for the assessment of coping strategies in patients suspected of CSE with neuropsychological complaints. Items for the CAMQ were based on existing coping dimensions and constructed by experts. The psychometric properties of the CAMQ were evaluated in a sample of 307 workers suspected of CSE. Factor analysis revealed four coping subscales: active coping, avoidance, acceptance, and seeking social support, all with good internal consistency (alphas .71-.78) and good test-retest reliability (ICCs .67-.82). The subscales demonstrated moderate correlations with related external constructs such as anxiety and depression, locus of control, meta-memory, mastery and generic coping styles. In conclusion, this study: (1) shows that the newly developed CAMQ is a reliable instrument, and (2) provides evidence for its validity in assessing coping with complaints of memory and attention in CSE-suspected patients. These results may serve for further study on coping with complaints of memory and attention, psychological adjustment and well-being in CSE patients.

Chronic solvent-induced encephalopathy: European consensus of neuropsychological characteristics, assessment, and guidelines for diagnostics

INTRODUCTION

The presence of neuropsychological impairment is a hallmark of chronic solvent-induced encephalopathy (CSE), and using clinical neuropsychological procedures to generate a valid assessment of the condition is crucial for its diagnosis. The goals of this consensus document are to provide updated knowledge of the neuropsychological characteristics of CSE and to provide internationally acceptable guidelines for using neuropsychological assessments in the process of diagnosing patients who are suspected of having CSE.

MATERIALS AND METHODS

A European working group that was composed of experts in the field of the clinical diagnosis of CSE met at several round-table meetings and prepared this report. The first section of the consensus paper addresses a review of the relevant literature that was published between 1985 and March 2012. The second section addresses recommendations for the clinical neuropsychological assessment of patients who are suspected of having CSE.

RESULTS

The literature review indicates that the most common neuropsychological impairments in CSE patients are within the domains of attention, particularly the speed of information processing, memory, and motor performance. It appears that the influence of CSE on memory processes mainly involves immediate recall and generally involves verbal, visual and visuospatial material. In the second section, six recommendations are presented regarding important functional domains for the neuropsychological diagnostic process of CSE that relate to the evaluation of neuropsychological impairment, the assessment and evaluation of symptoms, differential diagnostic considerations, the reliability and validity of neuropsychological test results, and the retesting of patients.

DISCUSSION AND CONCLUSIONS

These recommendations will contribute to the improvement of the process for accurately diagnosing CSE, better counselling for CSE patients, the comparability of epidemiological data between countries, and finally, by raising awareness, these recommendations will contribute to combating the adverse health effects of occupational exposure to solvents.

Prevalence of psychiatric disorders in patients with chronic solvent induced encephalopathy (CSE)

INTRODUCTION

Long term occupational exposure to organic solvents may induce chronic solvent-induced encephalopathy (CSE), characterized by mild to severe cognitive impairment, generally seen as the key diagnostic feature. Psychiatric disorders are often diagnosed in subjects with CSE, but were never studied in more detail. This study was designed to establish the prevalence rates of DSM IV mood, anxiety, and alcohol and substance related disorders in patients with CSE.

MATERIALS AND METHODS

In CSE, n=203 (consecutively recruited between 2002 and 2005), defined according to the criteria of the World Health Organisation (WHO), one month prevalence rates of DSM IV mood, anxiety, and life time alcohol/substance related disorders were assessed using the Structured Clinical Interview for DSM IV disorders (SCID). These prevalences were compared with those from an age and gender matched community sample (n=3212) while controlling for insufficient neuropsychological test effort.

RESULTS

In CSE, prevalence rates for major depressive disorder (n=36, relative risk (RR)=7.4), dysthymia (n=15, RR=6.0), panic disorders (n=18, RR=7.1), agoraphobia (n=7, RR=5.5) and generalized anxiety disorder (n=19, RR=15.8) were increased. Reduced prevalence rates were found for alcohol related disorders (n=21, RR=0.3). Insufficient neuropsychological test effort was not associated with increased prevalence rates of DSM IV disorders in subjects suspected of CSE.

DISCUSSION AND CONCLUSIONS

In conclusion, in this first large scale study in patients with CSE, prevalence rates of DSM IV mood and anxiety disorders were elevated as compared with those in the general community, while the prevalence rates of alcohol related disorders were reduced. Further study must determine whether CSE, and mood and anxiety disorders, share a same, solvent induced, neurobiological pathway, supporting the use of a more inclusive diagnostic approach. Additionally, randomised controlled trials are needed for the urgent issue of how to treat mood and anxiety disorders in CSE patients effectively.

The course of chronic solvent induced encephalopathy: a systematic review

BACKGROUND

Worldwide millions of workers are exposed to organic solvents. Long term exposure leads in some workers to the development of Chronic Solvent induced Encephalopathy (CSE). The first reports about CSE came from the European Nordic countries in the 1970s. In spite of decades of experience with this disease, little is known about the course and prognostic factors of CSE.

OBJECTIVE

To provide an overview of the evidence about the course and prognostic factors of CSE.

METHODS

A systematic review was conducted. Databases PubMed, PsycINFO (1970-2008) and EMBASE (1980-2008) were searched with the search strategy: solvent AND follow up AND (encephalopathy OR chronic intoxication). Inclusion criteria were: written in English, study population of CSE patients, follow-up time of at least 1 year. Included articles were assessed on methodological quality.

RESULTS

Sixty unique articles were retrieved of which sixteen met the inclusion criteria. Data extraction provided information about domains of neurology, neuropsychology, physical and mental health perceptions, and social consequences. In a number of studies no significant changes, and in other studies improvement of functioning could be measured. Prognostic factors resulting from included studies were summarized for each domain indicating a potential positive influence of younger age and lower exposure variables.

DISCUSSION

Due to the large heterogeneity of methodology no levels of evidence could be obtained. This review shows that there is a need for future research that addresses a variety of domains of functioning, hopefully resulting in an overall prognostic model for CSE.

CONCLUSION

Studies in this review are in agreement about CSE being a non-progressive disease in which no severe deterioration of functioning occurs after diagnosis. In a number of studies no significant changes, and in other studies improvement of functioning could be measured. Presumably cessation of exposure might be one of the causal factors for the non-progressive character of the disease as has been found. Future studies are needed to clarify the role of various prognostic factors on the course of CSE.

Cerebral impairment in chronic solvent-induced encephalopathy

OBJECTIVE

Worldwide, many workers experience occupational exposure to organic solvents, which may induce chronic solvent-induced encephalopathy (CSE). Disturbances within the frontostriatothalamic (FST) circuitry might explain the symptomatology of CSE. We tested the hypothesis of FST circuitry abnormalities in CSE, as well as associations with performance of psychomotor speed, attention, and solvent exposure. To detect preclinical, solvent-related effects, we also studied the FST circuitry in solvent-exposed, but asymptomatic workers.

METHODS

Ten CSE patients, 10 asymptomatic but solvent-exposed house painters (EC), and 11 nonexposed asymptomatic carpenters were included. Dopamine D(2) receptor (D2R) binding, central nervous system tissue metabolites, and fractional anisotropy were measured within the FST circuitry, using single-photon emission computed tomography, magnetic resonance spectroscopy, and diffusion tensor imaging. Performance of psychomotor speed and attention, and severity of solvent exposure were assessed.

RESULTS

Striatal D2R binding was reduced in CSE. In the solvent-exposed asymptomatic patients, striatal D2R binding and levels of N-acetylaspartate + N-acetylaspartyl-glutamate in frontal gray matter were reduced. In both exposed groups, a trend was seen for reduced choline in frontal gray matter. In CSE, the fractional anisotropy in the thalamus, caudate nucleus, and striatal D2R binding significantly predicted reduced performance of attention and psychomotor speed. In CSE, striatal D2R binding showed a negative correlation with solvent exposure.

INTERPRETATION

This is the first study in CSE showing pronounced disturbances within the FST circuitry that are related to the clinical findings and to exposure severity to solvents. The comparable, but milder, abnormalities within the FST circuitry in the exposed asymptomatic workers may imply a presymptomatic phase of CSE.

Subgrouping outpatients of an environmental medicine unit using SCL-90-R and cluster analysis

Between 1999 and 2003 all consecutive outpatients of the environmental medicine unit of the Charité hospital in Berlin were invited to participate in a study on environmentally related disorders. One hundred and sixty-nine of the patients completed a psychosocial questionnaire which comprised SCL-90-R and 14 other tests. When compared with clinical controls, SCL-90-R mean scores of the environmental patients (EP) were found to lie in between those of inpatients of a psychosomatic clinic and melanoma aftercare patients; but they were, with exception of the somatisation dimension, much closer to the latter. Application of the TwoStep Cluster component of SPSS resulted in three subgroups with high, moderate and low scores which were significantly different (p<0.001) although separation was incomplete (87% correct identification; cross-validated discriminant analysis). With all subgroups, scores for somatisation, depression and obsessive compulsion were highest and those for phobic anxiety and psychoticism were lowest. SCL-90-R scores correlated well with results of the Freiburg Personality Inventory, Whiteley Index of hypochondriasis, the short form health questionnaire (SF-36), and the Composite International Diagnostic Interview (CIDI). Hierarchical grouping (average linkage between groups), performed with involvement of SCL-90-R data from literature, resulted in a dendrogram with three distinct groups and three outliers. EP with low SCL-90-R scores were assigned to a group which comprised also general populations (USA, Germany), allergy patients, and melanoma controls. Those with moderate SCL-90-R scores were placed in a group together with chronic pain patients, and 26 'environmentally ill' subjects. The third subgroup of EP formed a cluster with our psychosomatic controls, psychosomatic patients from another study, depressed people, and patients undergoing psychotherapy. The three outliers of the dendrogram, however, were SCL-90-R profiles obtained from persons with toxic waste exposure, neurotoxic workplace exposure or with solvent-induced chronic toxic encephalopathy.

Self-reported symptoms and their effects on cognitive functioning in workers with past exposure to solvent-based glues: an 18-year follow-up

OBJECTIVES

To examine to what extent exposure to organic solvents during the working life affects general well-being in the long term, and to explore the relationship between self-reported symptoms and cognitive functioning in previously solvent-exposed floor layers.

METHODS

The study included 41 solvent-exposed floor layers and 40 unexposed referents participating in a longitudinal follow-up study 18 years after the baseline assessment. Symptom prevalence and level of spare time activities were studied using the same methods as in the initial study. These include a general health examination, the Q16 symptom questionnaire, and a questionnaire for spare time activities. Relationships between symptoms and cognitive functioning were analysed based on recently published data on cognitive functioning of the participants at follow-up.

RESULTS

At follow-up neuropsychiatric symptoms such as need to check things, depressive mood, and abnormal fatigue, were more prevalent among floor layers, particularly the most exposed individuals, than among referents. In addition, the most highly exposed floor layers reported more concentration difficulties and irritability. Fatigue and depressive mood increased over the follow-up time in the most exposed floor layers but not in the referents. Memory difficulties, although more frequent among floor layers than among referents, had decreased in floor layers while increased in referents. Floor layers also reported some negative effects on intimate relations and activity level. Neuropsychiatric symptoms were related to poorer performance chiefly in memory tasks and tests of complex attention and perceptual speed, more seldom in visuospatial tasks.

CONCLUSIONS

Findings of exposure-related, long-lasting, partly deteriorating neuropsychiatric complaints indicate that general well-being later in life has been affected in floor layers with past heavy solvent exposure. We also found frequent associations between symptom prevalence and the cognitive functioning. Together with previous findings of dose-related cognitive decrements, the present results strengthen the evidence that long-term heavy occupational solvent exposure may negatively interact with the normal ageing process.

Mortality of workers employed in shoe manufacturing: an update

BACKGROUND

In the late 1970s, the National Institute for Occupational Safety and Health identified two shoe manufacturing facilities where workers experienced relatively "pure" exposures to toluene. A mortality study was conducted through December 31, 1982. An original study did not detect elevated leukemia mortality but did detect increased lung cancer mortality. The present study is an update of the mortality of the original cohort.

METHODS

The study cohort consisted of workers employed 1 month or more between 1940 and 1979 at two Ohio shoe manufacturing plants. Vital status was ascertained through December 31, 1999.

RESULTS

Seven thousand eight hundred twenty eight workers, contributing 300,777 person years, were available for analysis. An excess of lung cancer deaths persisted with additional years of follow-up (SMR = 1.36, 95% confidence interval (CI) = 1.19-1.54). Trend tests did not indicate a positive trend between lung cancer risk and duration of employment. Mortality from leukemia was not significantly elevated in the updated analysis.

CONCLUSIONS

Results indicate a possible association between lung cancer mortality and exposure to chronic, low-levels of organic solvents. Although the strength of this conclusion was weakened by the lack of increasing lung cancer risk in relation to duration of employment, other studies have supported this association.

Education for men with solvent-induced chronic toxic encephalopathy and their spouses

In this study an education, and a series of group sessions for patients with solvent-induced chronic toxic encephalopathy (TE) and their spouses are evaluated. Thirty-eight patients and 21 family members participated in a 1-day education scheduled with short lectures on the clinical examination of chronic toxic encephalopathy and the prognosis. A specialist in occupational medicine, a psychologist and a social worker gave the lectures. Small discussion groups were also arranged. Of the participants from the educational days, 16 TE patients and 14 wives attended a 10-week counselling and coping improvement program with separate group sessions once a week, for patients and spouses. Questionnaires were used to assess symptoms, social network, mastery and family climate, and the participants' satisfaction with the education and the group sessions. The majority of the participants experienced the 1-day information as useful and relevant. The 10-week group sessions were rated as meaningful and the design, number, duration and frequency of the sessions equally good. Self-reported symptoms, social network and mastery were measured before the group sessions, and 3 and 9 months after breaking up the group sessions. In most measurements, there were no statistically significant differences between the three points in time. However, the wives improved more than did the patients but the effect was not lasting the whole follow-up period. Considering the patients' dependence on their wives, it might be most important that the wives experienced some relief from their own symptoms.

Longitudinal study to explore chronic neuropsychologic effects on solvent exposed workers

AIM

The aim of the study was to examine possible neurotoxic effects on the central nervous system (CNS) in relation to a chronic solvent exposure at the workplace.

METHOD

The collective included 127 workers exposed to solvent mixtures, such as spray painters and printers. They were examined twice by means of a physical examination, neuropsychological testbattery, biological and air monitoring.

RESULTS

Major component of the solvents were white spirits in concentrations up to 127 ppm in air and 2,666 microg/l in blood. Single substances were mainly toluene and xylenes in concentrations below current threshold values at the workplace. During the 2 yr interval, the concentrations of solvents decreased, and no significant associations between the neuropsychological tests and the solvent exposure were found. Regarding the whole working history of each participant, we found a significant reduction on information processing velocity and performance in the trailmaking test, as well as more complaints of workers with higher solvent exposure in the past.

CONCLUSIONS

A slight increase of subjective complaints and a deteriorated power of concentration seems to be associated with chronic solvent exposure.

Psychological distress and coping in women married to men with a diagnosis of solvent-induced chronic toxic encephalopathy

BACKGROUND

Solvent-induced chronic toxic encephalopathy (TE) is a slowly developing brain disorder associated with both a direct effect on the nervous system and as indirect experienced psychological distress. It can presumably also imply negative influence on the subject's social surroundings.

METHODS

Seventeen women married to men diagnosed with TE (WTE) and 51 referent women of the same age married to healthy husbands were examined. Symptoms, social network and coping style were measured by questionnaires.

RESULTS

The WTE reported slightly more psychological distress and fewer social contacts than did the referents. The WTE did not report affected stress management. Retired women in the WTE group accounted for most of the deviances from the referents.

CONCLUSIONS

The conclusion is that becoming a WTE does not necessarily imply more psychological distress, social isolation or poorer stress management capability if they continue with their work and social activities.

Psychological treatment of patients with chronic toxic encephalopathy: lessons from studies of chronic fatigue and whiplash

BACKGROUND

Chronic toxic encephalopathy (CTE), which can result from long-term exposure to organic solvents, is characterized by problems of attention and memory, fatigue and affective symptoms. There is little experience with (neuro)psychological treatment in this patient group. We reviewed treatment outcome studies of CTE and comparable syndromes, namely, chronic whiplash-associated disorder (WAD) and chronic fatigue syndrome (CFS), with a view to providing recommendations for the psychological treatment of patients with CTE.

METHODS

PubMed and PsychLIT were systematically searched and reference lists of retrieved articles were studied. The articles were classified according to study design and level of evidence.

RESULTS

The studies of CFS provided high-level evidence for the effectiveness of cognitive-behavior therapy (CBT) in challenging dysfunctional cognitions regarding the effectiveness of rest and in stimulating graded activity. The studies of WAD were methodologically weaker, and most evaluated a combination of CBT and graded activity training. There was some evidence that changing fatigue- or pain-related behaviors may result in cognitive improvement. Two uncontrolled studies of CTE evaluated cognitive rehabilitation techniques but yielded inconsistent findings.

CONCLUSIONS

CBT techniques focusing on changing illness attributions and on stimulating graded activity might be useful for patients with CTE, diminishing fatigue-related problems of concentration and memory. Future studies should evaluate whether cognitive deficits of CTE patients as a result of neurotoxic effects of exposure should be treated by cognitive rehabilitation.

Stress management in men with solvent-induced chronic toxic encephalopathy

Stress management was studied in male patients with solvent-induced chronic toxic encephalopathy (TE) of types 2A (TE 2A, n = 31) and 2B (TE 2B, n = 26). The patients were compared with a healthy reference group (n = 57). Self-reported symptoms (90-item Symptoms Checklist [SCL-90]), sense of coherence, coping strategies, and level of mastery were measured. As expected, both TE groups reported highly deviating symptoms on most SCL-90 scales. The TE 2B patients, who had objectified cognitive dysfunction, reported more use of passive, less situationally adequate coping strategies; a weaker sense of coherence; and a lower degree of mastery. In contrast, the TE 2A cases showed only minor deviations from the reference group in these respects. The results suggest that having a strong sense of coherence, a sense of mastery, and flexible resources for stress management could be dependent on intact brain functions.