Mental health status in systemic lupus erythematosus

Anti-Inflammatory Therapy as a Promising Target in Neuropsychiatric Disorders

This chapter analyzes the therapeutic potential of current anti-inflammatory drugs in treating psychiatric diseases from a neuro-immunological perspective. Based on the bidirectional brain-immune system relationship, the rationale is that a dysregulated inflammation contributes to the pathogenesis of psychiatric and neurological disorders, while the immunology function is associated with psychological variables like stress, affective disorders, and psychosis. Under certain social, psychological, and environmental conditions and biological factors, a healthy inflammatory response and the associated "sickness behavior," which are aimed to resolve a physical injury and microbial threat, become harmful to the central nervous system. The features and mechanisms of the inflammatory response are described across the main mental illnesses with a special emphasis on the profile of cytokines and the function of the HPA axis. Next, it is reviewed the potential clinical utility of immunotherapy (cytokine agonists and antagonists), glucocorticoids, unconventional anti-inflammatory agents (statins, minocycline, statins, and polyunsaturated fatty acids (PUFAs)), the nonsteroidal anti-inflammatory drugs (NSAIDs), and particularly celecoxib, a selective cyclooxygenase-2 (Cox-2) inhibitor, as adjuvants of conventional psychiatric medications. The implementation of anti-inflammatory therapies holds great promise in psychiatry. Because the inflammatory background may account for the etiology and/or progression of psychiatric disorders only in a subset of patients, there is a need to elucidate the immune underpinnings of the mental illness progression, relapse, and remission. The identification of immune-related bio-signatures will ideally assist in the stratification of the psychiatric patient to predict the risk of mental disease, the prognosis, and the response to anti-inflammatory therapy.

Systematic review of digital and non-digital non-pharmacological interventions that target quality of life and psychological outcomes in adults with systemic lupus erythematosus

BACKGROUND

Patients with systemic lupus erythematous (SLE) experience psychological comorbidities and impaired quality of life (QOL). We conducted a systematic review to examine the efficacy of non-pharmacological interventions for improving psychological outcomes and/or QOL in patients with SLE. To expand on a previous systematic review in this area and enhance our understanding of efficacious interventions for this population, our search included quasi-experimental and experimental studies of interventions delivered or supported by remote methods (including digitally) or in person.

METHODS

A comprehensive literature search was conducted with a research librarian using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and was registered before data extraction on the international prospective register of systematic reviews PROSPERO Web site (CRD42020154962). The search included controlled-vocabulary and title/abstract terms related to non-pharmacological interventions for SLE published through October 2019 in MEDLINE (Ovid), Cochrane Library databases (Wiley), Embase (Elsevier), CINAHL (EBSCO), PsycINFO (EBSCO), Web of Science (Clarivate), ACM Digital (Association of Computer Machinery), and IEEE Xplore. Studies were synthesized using a systematic narrative synthesis framework. Risk of bias was assessed.

RESULTS

Twenty-three studies were included: 21 randomized controlled trials and two quasi-experimental studies. Non-pharmacological diet, physical activity, psychological, and course-based interventions improved QOL and psychological outcomes, and were delivered in traditional settings (e.g., hospital) or remotely. No studies assessing digital non-pharmacological interventions were identified in our search. Quality assessments showed serious risk of bias for the two quasi-experimental studies, and high risk of bias in a subset of experimental studies.

CONCLUSIONS

Non-pharmacological interventions benefit patients with SLE. Future research should include more representative samples in rigorous evaluations and consider ways to incorporate digital technologies to increase accessibility.

The effect of suffering from rheumatoid arthritis, systemic lupus erythematosus, and back pain on sexual functioning and marital satisfaction in Iran

OBJECTIVE

Sexual functioning is an important component of life quality and musculoskeletal disorders may effect sexual functioning, so, the present study was conducted to evaluate sexual functioning in patients suffering from back pain, rheumatoid arthritis, and systemic lupus erythematosus (SLE).

METHODS

This study was conducted on 102 patients with rheumatoid arthritis, 103 patients with back pain, 103 patients with SLE, and 210 people in the control group by the consecutive sampling method. The marital satisfaction questionnaire (Enrich), Arizona Sexual Experience Scale (ASEX) questionnaire, and the General Health Questionnaire (GHQ-28) were completed by all the subjects. Disease severity was determined in each group of patients by Disease Activity Score of 28 joints, the Roland Morris questionnaire, and the SLE Disease Activity Index questionnaire.

RESULTS

The GHQ in rheumatoid arthritis and lupus patients was meaningfully higher than the control group (P < .05), while there was no meaningful difference between back pain patients and the control group (P = .414). The sexual functioning questionnaire score in all 3 groups showed no statistically meaningful difference with the control group (P < .05). Also, the marital satisfaction questionnaire score in all the groups showed no statistically meaningful difference compared to the control group (P = .791).

CONCLUSION

The study has shown that the level of sexual function in participants with back pain and the level of mental health and sexual functioning in patients with rheumatoid arthritis and SLE are significantly lower than healthy people and there is a need for intervention for improving mental health as well as sexual functioning in these patients.

Neuropsychiatric Involvement in Juvenile-Onset Systemic Lupus Erythematosus

Objective

Systemic lupus erythematosus (SLE) is a complex autoimmune disorder characterized by multisystem involvement, including the nervous system. In the present study, we aimed to assess neuropsychiatric manifestations in juvenile-onset systemic lupus erythematosus (JSLE) in Iran.

Methods

One hundred and forty-six pediatric onset patients with SLE who had registered in our pediatric rheumatology database were evaluated prospectively and cross sectionally within 2013-2015. Data including sex, age, age at the time of diagnosis, age at the time of study, physical examination, laboratory review, and neuropsychiatric inventory were extracted from this database. Classification of neuropsychiatric JSLE was according to the 1999 American College of Rheumatology (ACR) neuropsychiatric manifestations of SLE case definitions.

Result

A total number of 41 patients with neuropsychiatric symptoms were selected. The patients' average age was 12.2 years. The most common neuropsychiatric symptoms were seizures, migraine, and depression. The mean age at the onset of symptoms was 10.2 ± 3 years. Mean follow-up period was 57±34 (range: 12-120) months. From 41 SLE patients, 18 (43.9) presented symptoms at the time of diagnosis. In thirteen (31.7%) patients, neurological symptoms were developed more than 1 year after SLE diagnosis. Headache was the most common feature (13%), followed by seizure (9.5%) and chorea (3.4%). Other neurological manifestations included cranial nerve involvement (0.7%), loss of consciousness (2.7%), and impaired deep tendon reflex neuropathy (2.5%). The least common neuropsychiatric JSLE manifestation was aseptic meningitis seen in only one patient (0.7%).

Conclusion

The presence of headache, mood disorders, psychosis, depression, and other neuropsychological manifestations in a patient with JSLE should prompt investigations into diagnosis of the primary nervous system involvement in order to reduce mortality and morbidity.

A review of health related quality of life in systemic lupus erythematosus

Health-related quality of life (HRQoL) is an important outcome measure in patients with systemic lupus erythematosus (SLE). A review was undertaken of the literature relating to HRQoL in SLE. MEDLINE, EMBASE, CINAHL, Allied and Complimentary Medicine were searched to locate full papers in the English language reporting on HRQoL in adult SLE patients published between 1990 and 2005. In total 53 papers were included and the review was subdivided into: 1) description of HRQoL in SLE patients; 2) HRQoL and disease activity and/or damage; 3) the impact of other variables on HRQoL; and 4) HRQoL measures used in clinical trials in SLE patients. The findings were as follows: HRQoL is reduced in SLE patients; HRQoL is not correlated to disease activity or damage; age appears to have a negative impact on HRQoL especially physical health but the effect of disease duration is unclear; other potentially modifiable variables such as fatigue and psychosocial factors impact on HRQoL in a complex manner; and HRQoL measures which are sensitive to change should be an essential outcome measure in all clinical trials on SLE patients.

Psychosocial research on systemic lupus erythematosus: a literature review

This article is the first to review published research on psychosocial factors and behavioral interventions related to systemic lupus erythematosus (SLE). The first section presents descriptive studies, followed by studies that investigate psychosocial factors as predictor and outcome variables. These studies demonstrate that the consideration of psychosocial factors is critical to understanding the disease experience of persons with SLE. Next, studies of behavioral interventions are presented, leading to the conclusion that randomized controlled trials are essential yet rare. The final section highlights limitations of the extant literature and suggests directions for future research and recommendations for clinicians.

Depression in systemic lupus erythematosus patients is associated with link-polymorphism but not methylation status of the 5HTT promoter region

A higher prevalence of depression in systemic lupus erythematosus (SLE) patients has been reported, though the mechanism underlying this phenomenon remains unclear. The present study was conducted to explore whether the polymorphism and methylation status of the serotonin transporter gene (5HTT) promoter region (PR-5HTT) contribute to depression in SLE patients from both genetic and epigenetic perspectives. In this study, 96 SLE patients and 96 healthy controls (HCs) were recruited. Depression levels of all subjects were evaluated using the Hamilton Depression Rating Scale (HDRS). The serotonin transporter-linked polymorphism (5HTTLPR) and the DNA methylation status of PR-5HTT were detected in peripheral lymphocytes of SLE patients and HCs. The differences in 5HTTLPR and DNA methylation of PR-5HTT between SLEs and HCs were compared. In SLE patients, the frequencies of short allele (S) and SS genotype of 5HTTLPR were higher in depressive SLE (SLE-D) patients than in non-depressive SLE (SLE-ND) patients. The mean HDRS score of SS homozygote patients was higher than that of patients with SL/LL genotypes. Conversely, PR-5HTT was hypomethylated in HCs as well as SLE patients. There was no difference in the methylation status between HCs and SLEs. Thus, the functional expression of PR-5HTT may be primarily regulated by gene polymorphism and not by DNA methylation. The risk allele of 5HTTLPR appears to be a major contributor to depression in SLE patients.

Photodermatoses: environmentally induced conditions with high psychological impact

Photodermatoses are a group of skin disorders caused or exacerbated by ultraviolet and/or visible radiation, which collectively affect a high proportion of the population and substantially affect quality of life (QoL). Our objective was to assess the psychological impact of these conditions. Patients with a range of photodermatoses diagnosed at a specialist investigation centre in the UK completed questionnaires evaluating (i) anxiety and (ii) depression, using the Hospital Anxiety and Depression Scale (HADS), (iii) social anxiety, using the Fear of Negative Evaluation measure (FNE), (iv) coping strategies (brief COPE) and (v) QoL, using the Dermatology Life Quality Index (DLQI). Questionnaires were returned by 185 of 260 patients (71.1% response rate). Mean age was 50.2 years (SD 14.5, range 20-85), 80.3% female. Polymorphic light eruption was the most common diagnosis, followed by photoaggravated eczema, other photoaggravated dermatological conditions and solar urticaria. Across the sample, high percentages, i.e. 23% and 7.9% of individuals, showed scores indicating clinical levels of anxiety and depression, respectively. Facial involvement was a strong indicator for depression (t = 2.7, p < 0.01). In regression analyses psychological factors (particularly depression and adaptive coping) were the principle predictors of QoL, accounting for 17.7% of the variance (F = 7.61, p < 0.01), while clinical variables accounted for an additional 10.1% (F = 8.96, p < 0.01), with number of months/year affected exerting a significant effect (p < 0.01). This study demonstrates the high psychological comorbidity of these conditions; more awareness of this is required, with adoption of a biopsychosocial approach to their management.

Perceived illness stigma is associated with depression in female patients with systemic lupus erythematosus

OBJECTIVES

1) To assess the prevalence of depression in a sample of female patients with systemic lupus erythematosus (SLE) 2) To evaluate the association between perceived illness stigma and depression in those patients.

METHODS

In a cross-sectional study, 80 female SLE patients were evaluated for the presence of depression and perceived illness stigma. Depression was diagnosed using the Structured Clinical Interview for DSM-IV Axis Ι disorders, clinical version (SCID-I-CV), the severity of the depressive symptoms was evaluated using the Hospital Anxiety and Depression Scale-Depression Subscale (HADS-D), and the stigma of illness was assessed using the Stigma Impact Scale (SIS).

RESULTS

The prevalence of depression among female SLE patients was 18.75% (15/80). The perceived illness stigma was higher among the depressed group than among the non-depressed group (SIS mean scores were 43.87±7.87 and 26.62±3.79 respectively P<.001), there was a significant positive correlation between SIS and HAD-D scores (r=0.73, P=.002), and there was a significant association between perceived illness stigma and diagnosis of depression (R(2)=0.53, P=.002, odds ratio=3.2), which increased the severity of depressive symptoms (R(2)=0.64, P<.001).

CONCLUSION

This study demonstrates a significant association between illness stigma and depression in female SLE patients which may be important in promoting optimal coping for these women .

[Neuropsychiatric systemic lupus erythematosus (1st part). Cases definitions and diagnosis and treatment of central nervous system and psychiatric manifestations of systemic lupus erythematosus]

Systemic lupus erythematosus (SLE) is an autoimmune disease, which primarily affects skin and joints. Peripheral neurologic syndrome and central nervous system (CNS) manifestations are common in lupus patients but are not always attributable to lupus itself. A classification, published in 1999 by the American College of Rheumatology (ACR) research committee, described 12 CNS syndromes and seven peripheral neurologic syndromes compatible with "neuropsychiatric systemic lupus erythematosus" (NPSLE). Despite this consensus, studies which have been published since 1999 have reported a prevalence of NPSLE varying from 20 to 97 %, which shows the diagnosis difficulty and the heterogeneity of neuropsychiatric manifestations in SLE. In order to understand the limits of this classification, we propose in this first part an exhaustive review of publications describing neuropsychiatric manifestations according to the ACR 1999 classification. We also detail case definitions, prevalence and risk factors, clinical characteristics and diagnosis of each lupus-related psychiatric and CNS manifestation.

Fatigue: a principal contributor to impaired quality of life in ANCA-associated vasculitis

OBJECTIVES

To describe quality of life (QoL) in an ANCA-associated vasculitis (AAV) cohort and make comparisons with a general population sample. In addition, we aimed to take preliminary steps to identify potential disease and psycho-social factors which may determine QoL impairment.

METHODS

A population-based case-control study was designed. All AAV patients resident in Grampian, Scotland, were invited to participate as cases. Controls were identified from a random sample of persons registered with four local general practices. Participants completed a questionnaire comprising validated generic and symptom-specific tools in the assessment of QoL. In addition, all cases were clinically assessed and putative disease factors recorded. Cases and controls were compared and, in addition, disease and psycho-social associations were explored for identified QoL impairments.

RESULTS

In total, 74/90 (82%) cases and 781/2000 (39%) controls participated. Cases reported a significant impairment in physical health (P < 0.0001), but not mental health (P = 0.85), compared with controls, as measured by Short Form-8 (SF-8). Following adjustment for age and sex, persons with AAV were more than twice as likely to report mild/moderate fatigue [odds ratio (OR) 2.0; 95% CI 1.1, 3.8] or severe fatigue (OR 2.5; 95% CI 1.4, 4.5) compared with controls. Furthermore, among cases, fatigue was found to be strongly associated with impaired physical health (P < 0.0001), while disease factors such as disease activity and damage were not (P = 0.60 and 0.27, respectively).

CONCLUSIONS

Patients with AAV report impaired physical but not mental health. Specifically, fatigue is a principal complaint and appears to be a major determinant of impaired QoL.

Relationship of illness perceptions with depression among individuals diagnosed with lupus

BACKGROUND

The purpose of this study was to investigate the relationship of illness perceptions, as outlined in the Self-Regulatory Model of illness, with depression among individuals diagnosed with lupus.

METHODS

A mail-out questionnaire was completed by 154 members of the Australia Lupus Foundation and Lupus Foundation of New South Wales. Each questionnaire consisted of a Lupus Medical and Symptoms Questionnaire, the Illness Perceptions Questionnaire-Revised and the Cardiac Depression Scale.

RESULTS

Hierarchical regression analysis revealed that individuals who reported a perception of their illness as having negative life consequences, an unpredictable nature and themselves possessing little understanding of lupus, reported high levels of depression.

CONCLUSIONS

This study indicated the existence of a high level of depressive symptoms among individuals diagnosed with lupus, and reinforces the need for screening procedures in chronic illness, and treatment interventions that target maladaptive illness perceptions.

Major depressive disorder and disease activity in systemic lupus erythematosus

The association between psychosocial factors and systemic lupus erythematosus (SLE) is still a matter of discussion. Mood disorders may represent neuropsychiatric manifestations of SLE disease activity or may be a consequence of the stress of having a chronic major disease. We examined the hypothesis that SLE disease activity is related to the presence and severity of major depression in patients with SLE. Seventy-one patients with SLE were evaluated for the presence and intensity of major depressive disorder, psychosocial stressors, functional disability, SLE disease activity, and cumulative damage. Patients with major depression presented a trend toward having greater severity of SLE disease activity compared with those without major depression (P = .056). Major depression was also associated with life events (P = .017) and hassles (P < .001). Reinforcing these findings, depression severity was directly correlated with disease activity (r = 0.26, P = .026) and with functional disability (r = 0.46, P < .001). Moreover, multiple linear regression analysis, controlling for stressful life events and previous major depressive episodes, demonstrated that SLE disease activity still was associated with depression severity (P = .014). In conclusion, these results support the hypothesis that SLE disease activity is a potential risk factor for the presence and severity of major depression in patients with SLE. Whether major depression in active SLE is a central nervous system manifestation of the disease that is mediated by an autoimmune mechanism deserves further research.

Major life stress, coping styles, and social support in relation to psychological distress in patients with systemic lupus erythematosus

The objective of this study was to examine psychological processes in systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) patients in relation to measures of life stress, coping styles, social support and cognitive ability. Fifty-two SLE patients without overt neuropsychiatric symptoms, 29 RA patients and 27 healthy controls completed measures of depression, mood, disease activity, perceived health, stressful life events, coping, and social support. Variables entered into the multiple regression analysis following principal component analysis were: group, major difficult event, major life threatening event, disengaging coping, emotional coping, social support, and cognitive impairment. Depressive symptoms were associated with SLE group status (P < 0.001), major life-threatening events (P < 0.01), disengage coping (P < 0.001) and emotional coping (P < 0.05). SLE group status (P < 0.05), disengage coping (P < 0.05) and emotional coping (P < 0.05) were associated with current distressed mood. SLE patients without overt, major neuropsychiatric symptoms had greater psychological distress compared to RA and control subjects. Increased depressive symptoms and distressed mood state in SLE patients were related to use of disengaging and emotional coping styles. These findings are limited to SLE patients with no overt neuropsychiatric illness and low disease activity, suggesting the need for future studies with a greater variety of SLE patients. Interventions aimed at improving active coping and minimizing emotional response to stress may lower psychological distress in SLE patients with mild disease.

Improvement of coping abilities in patients with systemic lupus erythematosus: a prospective study

OBJECTIVE

To evaluate a novel specific psychological intervention aimed at improving coping in patients with systemic lupus erythematosus (SLE).

METHODS

34 community living SLE patients were recruited for the study. Intervention was undertaken in groups of up to eight patients and in two blocks over six months each. Eight patients were enrolled as a waiting list group. The 18 group sessions focused on information about the disease and specific problems of SLE patients, combining psychoeducative and psychotherapeutic elements. Psychological and medical evaluations were conducted at baseline and after three, six, and 12 months, using validated instruments.

RESULTS

The 34 SLE patients (91% female, mean age 42 years) improved significantly over a six month period on most of the psychological measuring instruments applied, such as depression, anxiety, and overall mental burden. The waiting list group showed no significant changes.

CONCLUSIONS

Conceptualised psychoeducational support may produce a significant and sustained improvement in coping skills of SLE patients and hence in their quality of life.

Illness intrusiveness explains race-related quality-of-life differences among women with systemic lupus erythematosus

Our objective was to investigate whether quality of life in systemic lupus erythematosus (SLE) differs across ethnoracial groups and to identify factors that may explain race-related differences. Self-administered questionnaire data from 335 White, 40 Black, and 30 Asian women with SLE were obtained from a multi-center database. Measures assessed illness intrusiveness, psychological well-being, depressive symptoms, musculoskeletal pain, and learned helplessness. Extent of SLE disease activity was indexed by self-reported functional-system involvement. Educational attainment was indicated by number of years in school. Principal-components analysis reduced the four psychosocial measures to a single factor score. This represented psychosocial well-being In path analysis. Psychosocial well-being differed significantly across the three groups, with Whites reporting the highest, and Blacks the lowest, levels. Path analysis indicated that illness intrusiveness accounted for this race-related difference. Although disease activity was significantly associated with psychosocial well-being, it did not differ across ethnoracial groups. Illness intrusiveness and educational attainment emerged as independent mediators of the race-related difference in psychosocial well-being. We conclude that race-related quality-of-life differences exist among women with SLE and are mediated independently by illness intrusiveness and educational attainment.

Quality of life and economic evaluation in SLE clinical trials

Outcome in SLE patients should include assessment of disease activity and chronic damage and also measurement of health-related quality of life and the economic impact of the disease. This paper reviews the methods available for doing this and the results of existing studies in SLE patients.

Psychosocial contributors to mental and physical health in patients with systemic lupus erythematosus

OBJECTIVE

To delineate psychosocial and systemic lupus erythematosus (SLE)-related medical factors that contribute to the mental and physical health of SLE patients.

METHODS

In a cross-sectional study, 44 women completed standardized instruments assessing daily hassles, social support, psychologic distress, and quality of life and underwent a physician examination to assess disease activity and disease damage. Four multiple linear regression analyses were computed to identify factors associated with the following outcomes: patient-perceived psychologic distress and global physical health and physician-assessed disease activity and damage. Variables entered into the regression analyses were: hassles severity, types of social support, SLE disease activity and damage, age, disease duration, education, ethnicity, and global psychologic distress (for the outcomes of self-perceived global physical health and disease activity and damage).

RESULTS

The best model explaining global psychologic distress included hassles severity and self-esteem social support. The best model explaining patients' perceptions of their global physical health included hassles severity and tangible social support. Psychologic distress accounted for a significant proportion of variance in both disease activity and damage.

CONCLUSION

High stress (assessed by hassles severity), poor social support, and psychologic distress--potentially modifiable variables--are associated with the mental and physical health of SLE patients.

Reduced preference for sucrose in autoimmune mice: a possible role of interleukin-6

In a continuous one-bottle sucrose intake test, 4-month-old autoimmune MRL-Ipr mice show a shift to the right along the X-axis of the concentration-intake function, compared to congenic MRL +/+ controls. Using a brief (60-min) and a continuous (48-h) two-bottle test, the present report examines potential factors that could account for the reduced responsiveness to a palatable stimulus. Study 1 examines whether preference for sucrose is associated with age, changes in food/water intake, or impaired renal function. Reduced preference for sucrose was observed in 5-6-week-old MRL-Ipr males, although food/water intake or blood creatinine levels did not differ from control values. Immunosuppressive treatment abolished this deficit, suggesting a role of immune factor(s). Study 2 tests the hypothesis that chronic upregulation of the neuroactive cytokine interleukin-6 (IL-6), reported to occur from 3 weeks of age in young MRL-Ipr mice, reduces preference for sucrose. Sustained administration of IL-6 was produced by infecting healthy MRL +/+, C3H.SW and Balb/C mice with adenovirus vector carrying cDNA for murine IL-6. This resulted in high serum IL-6 levels over 5 days, a rapid decline in preference for sucrose and low blood glucose levels. The results from Study 1 indicate that impaired sensitivity to sucrose in MRL-Ipr mice can be detected before autoimmune disease is florid in MRL-Ipr mice. The results from Study 2 are consistent with altered motivation/emotional states after infection, and point to sustained IL-6 production as an early mechanism in behavioral alterations during chronic autoimmune/inflammatory conditions.

Cognition and mood in systemic lupus erythematosus. Evaluation and pathogenesis

Cognitive dysfunction is frequent in SLE, probably related to primary underlying immune/inflammatory mechanisms operating in the brain. Longitudinal studies relating patterns of cognitive impairment to putative pathogenetic factors would provide evidence for this hypothesis. Such studies could also lead to more specific therapeutic interventions to ameliorate or reverse brain compromise in SLE.

Behaviour of MRL mice: an animal model of disturbed behaviour in systemic autoimmune disease

Evidence is reviewed indicating that development of lupus-like disease in the MRL-lpr substrain of mice coincides with a change in behaviour, suggestive of altered emotional reactivity and cognitive performance. The altered behaviour, termed 'autoimmunity-associated behavioural syndrome', is related to abnormal autoantibody and cytokine production. Moreover, immunosuppressive treatment with cyclophosphamide prevents the appearance of some behavioural deficits. It is argued that the MRL strain of mice constitute an animal model of behavioural dysfunction in autoimmune disease, and can be used to investigate the mechanisms by which an insidious autoimmune/inflammatory process alters mood and behaviour and may result in some forms of mental disorders.

Blunted sensitivity to sucrose in autoimmune MRL-lpr mice: a curve-shift study

Lupus-prone MRL-lpr mice show an autoimmunity-associated behavioral syndrome that has many features similar to the effects of chronic stress. The present study evaluated whether autoimmune MRL-lpr mice show reduced responsiveness to sucrose, as observed in normal animals exposed to chronic mild stress. Sixteen-week old MRL-lpr mice and their age-matched congenic MRL +/+ controls were given 0%, 0.5%, 1%, 2%, 4%, 8%, or 16% sucrose solution to drink every 48 h in a one-bottle test. The MRL-lpr mice drank less than controls at all concentrations, except at 16%. The amount of sucrose consumed vs. solution concentration followed a saturation curve. Estimates were obtained for the concentration yielding the half-maximum response (X50) and the response at saturating concentration of sucrose (Rmax). The X50 was significantly higher in MRL-lpr than in MRL +/+ mice, indicating a shift to the right of the concentration-intake curve. The Rmax did not differ significantly between substrains, suggesting that the autoimmune process did not affect performance capacity. Pretreatment with the immunosuppressant cyclophosphamide diminished the substrain difference in X50, suggesting that reduced sensitivity to sucrose is related to autoimmune/inflammatory factors. These results support the similarity between autoimmunity-associated behavioral syndrome and behavioral changes produced by chronic stress, and suggest common neuroendocrine mechanisms. Because reduced sensitivity to palatable stimulus may reflect blunted hedonic responsiveness ("anhedonia"), it is hypothesized that an autoimmune/inflammatory factor(s) produces the depression found in human lupus, and some cases of affective disorder.