The immune system and major depression

Do patients with skin allergies have higher levels of anxiety than patients with allergic respiratory diseases? Results of a large-scale cross-sectional study in a French population

BACKGROUND

Psychological comorbidity is a known aspect of allergic disease. However, there is recent evidence that a large proportion of allergic patients remains undiagnosed and untreated for psychological disease. In addition, the complexities of the anxiety-allergy relationship, i.e. differences for current and past disease, or differences among allergic disease types, are not well understood.

OBJECTIVES

To measure the level of anxiety in a large allergic population in France using a standardized measure, the State/Trait Anxiety Inventory (STAI).

METHODS

Allergy patients in France (n = 3939) who visited their allergy specialists participated in the study. The patients completed a questionnaire which was then linked to the questionnaire completed by their physician. Only patients with both subject and physician questionnaire were kept in the analyses. Mean STAI scores for the State (S) and Trait (T) scales were obtained for each allergic disease. ANCOVA models testing group differences on the mean scores, using the categories "current disease", "past disease" and "allergic disease ever", were assessed along with relevant confounders.

RESULTS

Allergic rhinitis (AR), asthma and atopic dermatitis (AD) were the most prevalent conditions of the 12 allergic diseases assessed in the study. Women had higher mean STAI S/T scores than men and age was also found to be associated with higher S scores; therefore, both age and gender were included as covariates where relevant. A single ANCOVA model for each STAI scale showed a statistical difference among the various allergic diseases. Using the category "current disease" each allergic disease was assessed separately regarding the presence or absence of that disease. Higher, statistically significant mean STAI scores were found for AD and allergic urticaria on the S scale and for AD on the T scale. Similarly, for the category "allergic disease ever", AD and allergic urticaria reached statistical significance on the S scale, while on the T scale only AD was statistically significant. When patients were assessed for anxiety based on their past disease, asthma, AR and sinusitis were significant on the S scale while asthma and nasal polyps were statistically significant on the T scale. When asthma and AD were tested simultaneously, only the latter was significant.

CONCLUSIONS

High mean scores for State and Trait anxiety were mostly associated with AD.

Long-chain polyunsaturated fatty acids in childhood developmental and psychiatric disorders

Both omega-3 and omega-6 long-chain PUFA (LC-PUFA) are crucial to brain development and function, but omega-3 LC-PUFA in particular are often lacking in modern diets in developed countries. Increasing evidence, reviewed here, indicates that LC-PUFA deficiencies or imbalances are associated with childhood developmental and psychiatric disorders including ADHD, dyslexia, dyspraxia, and autistic spectrum disorders. These conditions show a high clinical overlap and run in the same families, as well as showing associations with various adult psychiatric disorders in which FA abnormalities are already implicated, such as depression, other mood disorders, and schizophrenia. Preliminary evidence from controlled trials also suggests that dietary supplementation with LC-PUFA might help in the management of these kinds of childhood behavioral and learning difficulties. Treatment with omega-3 FA appears most promising, but the few small studies published to date have involved different populations, study designs, treatments, and outcome measures. Large-scale studies are now needed to confirm the benefits reported. Further research is also required to assess the durability of such treatment effects, to determine optimal treatment compositions and dosages, and to develop reliable ways of identifying those individuals most likely to benefit from this kind of treatment. Childhood developmental and psychiatric disorders clearly reflect multifactorial influences, but the study of LC-PUFA and their metabolism could offer important new approaches to their early identification and management. Heterogeneity and comorbidity are such, however, that a focus on specific traits or symptoms may prove more fruitful than an exclusive reliance on current diagnostic categories.

Serotonin, serotonin 5-HT(1A) receptors and dopamine in blood peripheral lymphocytes of major depression patients

There are increasing evidences of cell markers present in the immune and the nervous systems. These include neurotransmitter receptors and transporters. Serotonin receptor subtypes are related to depression and also have been shown to be present in certain cells of the immune system. In the present report, we determined the presence of 5-HT(1A) receptors by the binding of the selective agonist 8-hydroxy-2-(di-n-propyl-amino)tetralin in lymphocytes of peripheral blood isolated by Ficoll/Hypaque gradients from controls and depressed patients. The capacity of these receptors was around 24 fmol/10(6) cells in both groups of subjects, without significant difference among them. The affinity was in the nM range and either differ between controls and patients. Serotonin, 5-hydroxyindoleacetic acid, dopamine and 3,4-dihydroxyphenylacetic acid were determined by HPLC with electrochemical detector. There were no significant differences between controls and major depression patients in the values obtained for rich and poor platelet plasma or in the isolated cells. However, there was a reduction in serotonin turnover rate indicated by an increase in the ratio serotonin/5-hydroxyindoleacetic acid, but not in that of dopamine, in lymphocytes of major depression patients. Thus, there is a serotonergic dysfunction in immune circulating cells of major depression patients, without changes in the number of 5-HT(1A) receptors, although the coupling of these receptors to transduction mechanisms could be affected and may be related to the alteration of 5-HT turnover rate.

Relationship between depression and pancreatic cancer in the general population

OBJECTIVE

Prior research suggesting a relationship between pancreatic cancer and depression conducted on clinical populations has been subject to recall bias. We reexamined this association using longitudinal population-based data.

METHODS

This was a retrospective cohort study using longitudinal insurance claims data.

RESULTS

Men with mental disorders were more likely to develop pancreatic cancer than those without psychiatric claims (odds ratio 2.4, confidence interval 1.15-4.78). Depression more commonly preceded pancreatic cancer than it did other gastrointestinal malignancies (odds ratio 4.6, confidence interval 1.07-19.4) or all other cancers (odds ratio 4.1, confidence interval 1.05-16.0).

CONCLUSIONS

Depression and pancreatic cancer are associated in the general population.

Lung disease and internalizing disorders. Is childhood abuse a shared etiologic factor?

OBJECTIVE

To investigate the role of childhood abuse in the relationship between panic attack, depression and lung disease among adults in the population.

METHODS

Data were drawn from the National Comorbidity Survey (n=5877), a representative sample of adults age 15-54 in the United States. Multiple logistic regression analyses were used to determine the association between childhood abuse and lung disease, and to determine whether childhood abuse is an independent predictor of the co-occurrence of lung disease, panic attack and depression.

RESULTS

Childhood abuse was associated with significantly increased odds of panic attacks (OR=2.2 (1.5, 3.1)) and depression (OR=1.6 (1.1, 2.3)). Childhood abuse increased likelihood of lung disease (OR=1.5 (1.1, 2.2)). Childhood abuse independently predicted the co-occurrence of lung disease, panic attack and depression (OR=10.7 (2.2, 51.5)).

CONCLUSION

These data are preliminary, but if replicated, suggest that childhood abuse may be associated with increased risk of lung disease during adulthood, and further may reflect a shared vulnerability for the co-occurrence of lung disease, panic attack and depression in the community. Future studies are needed to further explore the mechanism of this association.

From farm to table to brain: foodborne pathogen infection and the potential role of the neuro-immune-endocrine system in neurotoxic sequelae

The American diet is among the safest in the world; however, diseases transmitted by foodborne pathogens (FBPs) still pose a public health hazard. FBPs are the second most frequent cause of all infectious illnesses in the United States. Numerous anecdotal and clinical reports have demonstrated that central nervous system inflammation, infection, and adverse neurological effects occur as complications of foodborne gastroenteritis. Only a few well-controlled clinical or experimental studies, however, have investigated the neuropathogenesis. The full nature and extent of neurological involvement in foodborne illness is therefore unclear. To our knowledge, this review and commentary is the first effort to comprehensively discuss the issue of FBP induced neurotoxicity. We suggest that much of this information supports the role of a theoretical model, the neuro-immune-endocrine system, in organizing and helping to explain the complex pathogenesis of FBP neurotoxicity.

[Psychoimmunology: a questionable model?]

INTRODUCTION

The concept of "psychoimmunology" that had long been supported by clinical observation and common sense, has acquired a sound scientific basis in the last two decades. The discovery of neuro-mediators and cytokines and their receptors shared by the central nervous system and the immune system has prompted research work using reliable methodologies to study the relationship between a 'hard' scientific field, such as immunology, and a 'soft' one, such as the behavioral sciences.

CURRENT KNOWLEDGE AND KEY POINTS

The complexity of the studies on stress and immunity lies upon the choice of immunological measurements and the development of reproducible stress protocols. Models of stress in experimental animals may address acute versus chronic stress, and individual versus social stress. In humans, typical situations such as academic exams, and care given to patients with dementia, for instance, have been chosen to study large groups of subjects. The development of self-questionnaires for a reliable evaluation of stress and its consequences has led to more accurate measurements of psychosocial events. In animals, acute stress usually drives the immune response towards a Th2, grossly 'immunosuppressive,' profile. In humans, acute stress associates an endocrine response (characterized by glucocorticoid secretion and hyperprolectinemia) with an immunosuppression. Chronic stress is more likely to induce a range of effects, depending on the capacity of the subject to cope with stress, and on his/her social environment. Among the numerous mediators of the hypothalamo-pituitary cascade, Corticotropin Releasing Hormone is a key factor in the stress-immunity relationship. Several studies in humans have demonstrated the influence of stress on the susceptibility to infections (including HIV infection) and on survival in malignant diseases. In autoimmune diseases, a high prevalence of depression, as well as a particular sensitivity to stressful events, seem to modify the course of conditions such as systemic lupus erythematosus, rhumatoid arthritis or Sjögren's disease. The relationship between stress and diseases is based on the pathogenic model which involves the following chain of events: stressor, reaction to stress, neuro-endocrine changes, abnormalities of the immune response, and occurrence (or aggravation) of a disease. The evolution from health to disease could be associated, at least partially, with a 'passive' immunosuppressive mode of response, mediated by the pituitary-adrenal axis, typically the opposite of an 'active,' immunostimulant mode of response, mediated by adrenergic stimulation.

FUTURE PROSPECTS AND PROJECTS

Concept-related problems still remain to be solved: adaptation to stress ('coping'), is both genetically and socially mediated; the significance and interpretation of stress-related abnormalities and their precise involvement in the pathogenesis of diseases may be ambiguous. However, available epidemiological and pathophysiological evidence is currently sufficient to allow physicians in their everyday practice to take stress and depression into account in order to markedly improve the prognosis of many diseases related to immune responses. Prospective studies of neuropsychological intervention, using either pharmacologic or behavioral approaches, should be made to provide the necessary rational to a psychoimmunological management of patients.

Bulimia nervosa and autoimmunity

The autoantibodies that react with dopamine and serotonin are of interest in the study of bulimia nervosa. These neurotransmitters play an important role in appetite control, sexual and social behavior, and stress responses, all of which form a part of the clinical picture of bulimia nervosa. Are these autoantibodies involved in the serotoninergic hypofunctioning present in bulimia nervosa? Are they a part of an immunity regulation system essential for the cerebral system's homeostasis? To address these questions, 31 bulimic females (diagnosed according to DSM-III-R criteria) were compared with 10 control subjects (matched to the patients for sex, age, and demographic/psychosocial features). Measurement of the activity of natural autoantibodies reacting with dopamine, dopamine-beta-hydroxylase and serotonin was performed by an enzyme-linked immunosorbent assay (ELISA) for typical immunoglobulins (IgG, IgM, IgA). All of the autoantibodies of the IgG type were lower in the bulimic group than in the control group, a difference that was statistically significant for IgG anti-serotonin and IgG anti-dopamine. There was a trend for the amount of IgM anti-dopamine to be lower in patients than in controls. Dopamine and serotonin are specific components of brain cells. It can therefore be hypothesized that these antigens acting with autoantibodies could be the antigenic cerebral targets reacting with 'anti-brain' antibodies. The study of these specific autoantibodies provides information about the immunological characteristics that may be related to brain disturbances.

Depression and bipolar disorder: relationships to impaired fatty acid and phospholipid metabolism and to diabetes, cardiovascular disease, immunological abnormalities, cancer, ageing and osteoporosis. Possible candidate genes

Depression and bipolar disorder are two of the commonest illnesses in the developed world. While some patients can be treated effectively with available drugs, many do not respond, especially in the depression related to bipolar disorder. Depression is associated with diabetes, cardiovascular disease, immunological abnormalities, multiple sclerosis, cancer, osteoporosis and ageing: in each case depressed individuals have a worse outcome than non-depressed individuals. In all of these conditions there is now evidence of impaired phospholipid metabolism and impaired fatty acid-related signal transduction processes. Impaired fatty acid and phospholipid metabolism may be a primary cause of depression in many patients and may explain the interactions with other diseases. Several novel gene candidates for involvement in depression and bipolar disorder are proposed.

Assessment and treatment of depression in the cancer patient

The prevalence, diagnosis, and treatment of depression in the cancer patient are reviewed. Although frequently encountered in the cancer patient population, depression often remains undiagnosed and untreated. This carries grave consequences in that depressed cancer patients experience a poorer quality of life, are less compliant with medical care, have longer hospital stays, and have higher mortality rates. Diagnostic assessment of depression in the cancer patient raises difficulties both upon phenomenological and etiological grounds. In particular, the presence of neurovegetative symptoms which may be secondary to either cancer or depression may cloud the diagnostic picture. Due to the serious consequences of unrecognized depression, a more sensitive inclusive approach to diagnosis is recommended in the clinical setting. Finally, the limited data regarding treatment of depression in patients with cancer is reviewed. This includes a discussion of both psychosocial and pharmacological interventions which are shown to alleviate depression, improve quality of life measures, improve immune function, and lengthen survival time.

Plasma neopterin in major depression: relationship to basal and stimulated pituitary-adrenal cortical axis function

We measured plasma neopterin at baseline and after oCRH and ACTH(1-24) stimulation tests in 35 unmedicated, adult major-depressive patients (mean age = 41 +/- 12 years) and in 35 normal control subjects individually matched to the patients. Neopterin is released by gamma-interferon-stimulated macrophages; because gamma-interferon is secreted by activated T-lymphocytes, elevated circulating neopterin is considered to reflect activation of the cell-mediated immune system. Plasma ACTH(1-39) and cortisol also were measured as indicators of pituitary-adrenal axis activity. Baseline plasma neopterin did not differ significantly between patients and controls (medians = 6.25 and 6.57 microg/l, respectively), but the baseline neopterin:creatinine ratio showed a trend toward lower values in the patients (P < 0.07). There was no apparent plasma neopterin change from baseline (area under the curve-AUC) following oCRH or ACTH(1-24) administration in either group of subjects. As with baseline neopterin, there was no significant patient-control difference in neopterin AUC following either hormone challenge, but there were trends toward lower neopterin:creatinine ratios in the patients following both challenges. In the patients, neither baseline neopterin nor neopterin AUCs following hormone challenge were significantly correlated with age, duration of depressive episode, lifetime number of episodes, melancholic subtype, Hamilton Depression Scale total score, Hamilton factor scores, or the Hamilton suicidality item score.