Inflammation in depression: is adiposity a cause?

Obesity moderates the complex relationships between inflammation, oxidative stress, sleep quality and depressive symptoms

BACKGROUND

The relationship between obesity and depression is complex. This study assessed the impact of body mass index (BMI) on the link between BMI, inflammation, oxidative stress, sleep quality and self-reported depressive symptoms.

METHODS

We used data from the U.S. National Health and Nutritional Examination Survey 2005-2008 cycles (n = 9133; ≥20y). Depressive symptoms and sleep quality were determined from questionnaires. C-reactive Protein (CRP) was used as a biomarker of inflammation and γ-glutamyltransferase was used to assess oxidative stress. The relationship between depressive symptoms, sleep quality, and biomarkers were assessed with regression models. The moderating effects of BMI and sex were tested.

RESULTS

BMI was a significant moderator of the relationship between γ-glutamyltransferase and depressive symptoms (p = 0.02), but not CRP or sleep quality. Higher BMI increased odds of depressive symptoms in women (OR (95% CI): 3.92 (1.85-8.30) for BMI ≥25 to < 30 kg/m2; 3.17 (1.53-6.58) for BMI ≥30 to < 35 kg/m2; and 7.38 (2.11-25.76) for BMI ≥35 kg/m2). BMI was also a significant moderator of γ-glutamyltransferase levels in those with vs without depressive symptoms. Those with depressive symptoms had 24% poorer sleep quality compared to those without depressive symptoms after adjusting for inflammation, oxidative stress and other confounders.

CONCLUSIONS

The link between oxidative stress and depressive symptoms may be particularly relevant for females and people living with obesity. People with depressive symptoms also have a substantial reduction in sleep quality. Thus, research should examine these relationships prospectively to inform and improve the mental health of the adult population in developed countries.

Inflammatory gene expression in adipose tissue according to diagnosis of anxiety and mood disorders in obese and non-obese subjects

Psychiatric disorders have been widely reported to be associated with systemic inflammation upregulation and adiposity. However, there are no data that link adipose tissue inflammation to these mental disorders. The analysis of adipokines and inflammation-related markers in adipose tissue could help to elucidate the potential association between obesity and mental health. An observational study was conducted in samples of patients consisting of non-obese and obese subjects, who were diagnosed with anxiety or mood disorders. Gene expression of adiponectin (ADIPOQ), leptin (LEP) and inflammatory markers (IL6, IL1B, TNF, CCL2, CSF3, ITGAM, and PLAUR) were determined in visceral (VAT) and subcutaneous (SAT) adipose tissues. Our results showed that the gene expression of adipokines and inflammation-related markers was higher in the VAT and SAT of obese subjects compared with non-obese subjects. Regarding mental disorders, all the inflammatory genes in the VAT were significantly higher in non-obese subjects with anxiety or mood disorders than in subjects without mental disorders, except for TNF and ITGAM. Additionally, IL6 expression was significantly lower in SAT. In contrast, obese patients diagnosed with anxiety or mood disorders only showed significantly lower expression levels of IL1B in VAT and ADIPOQ in SAT when compared with obese subjects without mental disorders. These data suggest the potential involvement of VAT inflammation in anxiety and mood disorders, involving complex mechanisms which are strongly affected by obesity.

Rapid effectiveness of intravenous ketamine for ultraresistant depression in a clinical setting and evidence for baseline anhedonia and bipolarity as clinical predictors of effectiveness

BACKGROUND

Intravenous ketamine has been established as an efficacious and safe treatment, with transient effect, for treatment-resistant depression. However, the effectiveness of intravenous ketamine in non-research settings and with ultraresistant depression patients remains understudied.

AIMS

This study aims to measure the response and remission rates in ultraresistant depression patients in a clinical setting by means of a retrospective, open label, database study. Secondarily, the study will attempt to support previous findings of clinical predictors of effectiveness with intravenous ketamine treatment.

METHODS

Fifty patients with ultraresistant depression were treated between May 2015-December 2016, inclusive, in two community hospitals in Edmonton using six ketamine infusions of 0.5 mg/kg over 40 min over 2-3 weeks. Data were collected retrospectively from inpatient and outpatient charts. Statistical analysis to investigate clinical predictors of effectiveness included logistic regression analysis using a dependent variable of a 50% reduction in rating scale score at any point during treatment.

RESULTS

At baseline, the average treatment resistance was severe, with a Maudsley Staging Method score of 12.1 out of 15, 90.0% were resistant to electroconvulsive therapy, and the average Beck Depression Inventory score was 34.2. The response rate was 44% and remission rate was 16%. As a single predictor, moderate or severe anhedonia at baseline predicted a 55% increased likelihood of response. As a combined predictor, this level of anhedonia at baseline with a diagnosis of bipolar depression predicted a 73% increase in likelihood of response.

CONCLUSION

In a clinical setting, intravenous ketamine showed effectiveness in a complex, severely treatment-resistant, depressed population on multiple medication profiles concurrently. This study gave support to anhedonia and bipolar depression as clinical predictors of effectiveness.

Obesity and depressive symptoms in mid-life: a population-based cohort study

BACKGROUND

Obesity and depression are both highly prevalent public health disorders and evidence on their relationship is inconsistent. This study examined whether depressive symptoms are associated with current obesity, and further, whether obesity in turn is associated with an increased odds of depressive symptoms five years later after accounting for potential lifestyle confounders and depressive symptoms at baseline.

METHODS

Data were obtained from the 1958 British birth cohort (N = 9217 for cross-sectional and 7340 for prospective analysis). Clinical Interview Schedule-Revised and Mental Health Inventory-5 were used for screening depressive symptoms at ages 45 and 50 years, respectively. General and central obesity were defined using measurements of body mass index (BMI) and waist circumference (WC) at 45 years, respectively.

RESULTS

There was a cross-sectional association between depressive symptoms and obesity: participants with ≥2 depressive symptoms had 31% (95%CI 11% to 55%) higher odds of general and 26% higher odds of central obesity (95%CI 8% to 47%). In prospective analyses, both general and central obesity were associated with higher odds of depressive symptoms five years later among women but not in men (P_interaction < 0.01). After adjustment for depressive symptoms at baseline, sociodemographic and lifestyle factors, women with general obesity had 38% (95% CI 7% to 77%) and women with central obesity 34% (95%CI 9% to 65%) higher odds of depression compared to others.

CONCLUSIONS

Depressive symptoms are associated with concurrent obesity and related lifestyle factors among women and men in mid-life. Our study suggests that obesity in turn affects long-term risk of depressive symptoms in women but not in men, independently of concurrent associations, providing an important target group for the implementation of preventative strategies.

Does obesity along with major depression or anxiety lead to higher use of health care and costs? A 6-year follow-up study

Background

Evidence lacks on whether obesity along with major depression (MD)/anxiety leads to higher health care use (HCU) and health care-related costs (HCC) compared with either condition alone. The objective of the study was to examine the longitudinal associations of obesity, MD/anxiety, and their combination with HCU and HCC.

Methods

Longitudinal data (2004-2013) among N = 2706 persons at baseline and 2-,4-, and 6-year follow-up were collected on obesity, MD/anxiety and HCU.

Results

The combination of obesity and MD/anxiety was associated with an increased risk of primary and specialty care visits, and of hospitalizations, odds ratios (95%-confidence intervals): 1.83 (1.44; 2.34), 1.31 (1.06; 1.61) and 1.79 (1.40; 2.29) compared to non-obese and non-depressed individuals. The primary and specialty care costs were higher in persons with obesity and MD/anxiety than in persons without these conditions, but the relative excess risk due to interactions between obesity and MD/anxiety regarding HCU and HCC were not statistically significant (i.e. no synergistic effect).

Conclusions

Obesity along with MD/anxiety leads to higher HCU and HCC over time. However, the HCC associated with the joint presence of both conditions are not higher than the sum of the HCC due to each condition independently.

The Mediating Role of Overweight and Obesity in the Prospective Association between Overall Dietary Quality and Healthy Aging

BACKGROUND

Our objective was to quantify to what extent the association between adherence to the French nutritional recommendations at midlife, measured by the Programme National Nutrition Santé-Guideline Score (PNNS-GS), and healthy aging (HA) is mediated by body mass index (BMI) status.

METHODS

We analyzed data from 2249 participants of the French 'Supplementation with Vitamins and Mineral Antioxidants' (SU.VI.MAX-'SUpplémentation en VItamines et Minéraux AntioXydants') cohort. At baseline (1994⁻1995), data on BMI status (<25 vs. ≥25 and <30 vs. ≥30) and diet were collected. At follow-up (2007⁻2009), HA status (yes/no) was evaluated via a multidimensional concept focusing on chronic disease incidence, physical and cognitive functioning, mental and social health, pain, and perceived health. Relative risks (RR) were estimated by extensively adjusted robust-error-variance Poisson regression, and counterfactual-based mediation analysis was performed.

RESULTS

Our HA criteria were met by 39% of participants. We identified a positive direct relation of a greater adherence to the French nutritional recommendations, with the probability of HA (RR_Quartile ₄ _vsquartile ₁ = 1.31 (95% confidence interval (CI) = 1.13, 1.53)), and an indirect relation mediated by BMI status (1.01 (95% CI: 1.01, 1.02)), accounting for 5% of the total relation.

CONCLUSION

These results indicate that high dietary quality may contribute to the preservation of overall health during aging, partly via obesity prevention and partly via other mechanisms.

Depression with inflammation: longitudinal analysis of a proposed depressive subtype in community dwelling older adults

OBJECTIVE

It has been proposed that inflammation may be causally related to depression. If this is the case, it may be possible to distinguish an inflammatory depressive subtype according to illness course, pattern of co-morbidity and symptom profile.

METHODS

Eight hundred and eleven community dwelling older adults with depression (8 item Center for Epidemiologic Studies scale ≥ 4) from the English Longitudinal study of Ageing (ELSA) were followed for a median of 47 months. Participants with depression and inflammation (C Reactive Protein > 3 mg/l) were compared to those with depression alone.

RESULTS

In a longitudinal analysis, depression with associated inflammation was more likely to persist over time. This association was independent of baseline depression severity and medical co-morbidity (OR 1.47 95% CI 1.03 - 2.10, p = 0.034) but was no longer significant following further adjustment for body mass index (OR 1.37 95% CI 0.94 - 2.01, p = 0.106). Inflammation either partially or completely mediated the association between medical co-morbidity, body mass index and depression at follow-up. Depression with inflammation was associated with more amotivation, less sadness, greater medical co-morbidity and higher body mass index.

CONCLUSIONS

Our findings provide some support for an inflammatory contribution to depression. This subgroup has a worse prognosis and may benefit from interventions targeting co-morbidity, body mass index and associated inflammation. Copyright © 2016 John Wiley & Sons, Ltd.

[Nutrition and mental diseases : Focus depressive disorders]

Dietary interventions are currently being discussed as additional treatment options for mental disorders. The pathological mechanisms are not yet fully understood. It is hypothesized that certain nutrients and dietary pattern influence immune and inflammatory processes, the microbiome, the leptin-melanocortinergic axis and hypothalamic-pituitary axis, as well as neurotransmitters of the cholinergic, noradrenergic, dopaminergic and serotonergic signaling cascades and neurotrophins. Observational studies have shown that traditional dietary patterns, such as the Mediterranean diet have a protective effect on mental health. Supplementation with long-chain polyunsaturated omega-3 fatty acids showed small to medium but significant effect sizes in meta-analyses from depression trials. The evidence with respect to the antidepressive effect of vitamin D supplementation is currently inconclusive.

Associations between obesity and mental distress in late midlife: results from a large Danish community sample

BACKGROUND

To examine associations of Body mass Index (BMI) and mental distress in late midlife in a large Danish community sample and to investigate the effect of socio-demographic factors.

METHODS

The study sample comprised 3613 Danish men and 1673 women aged 49-63 years from the Copenhagen Ageing and Midlife Biobank (CAMB) with complete information on measured BMI, severity of mental symptoms assessed by the Symptom Check-List' (SCL-90), and socio-demographic factors including sex, age, occupational social class, and educational duration. Linear and logistic regression were used to evaluate associations between BMI category and SCL-90.

RESULTS

Unadjusted SCL-90 subscale scores differed significantly across BMI categories (p < 0.001) among both men and women with more mental distress in the underweight, obese and severely obese BMI categories except for the anxiety scale which was not associated with BMI category in women. In the adjusted analyses, all symptom scales remained significantly associated with BMI among men after adjusting for socio-demographic factors while only associations with somatization and depression scales remained significant for women.. When SCL-90 case status was applied as an outcome, significant unadjusted associations with BMI category were observed for somatization (p < 0.001), depression (p = 0.026) and the General Severity Index (p = 0.002) among men and somatization (p = 0.002) among women. Furthermore, somatization case-status was significantly predicted by BMI category (p < 0.001) in men after adjusting for socio-demographic factors.

CONCLUSION

Results indicate more mental distress among underweight, obese and severely obese men and women after adjusting for socio-demographic factors. Furthermore, obese men have higher risk of reporting clinically relevant symptoms of somatization independently of socio-demographic factors.

Long-Term Fine Particulate Matter Exposure and Major Depressive Disorder in a Community-Based Urban Cohort

BACKGROUND

Previous studies have associated short-term air pollution exposure with depression. Although an animal study showed an association between long-term exposure to particulate matter ≤ 2.5 μm (PM2.5) and depression, epidemiological studies assessing the long-term association are scarce.

OBJECTIVE

We aimed to determine the association between long-term PM2.5 exposure and major depressive disorder (MDD).

METHODS

A total of 27,270 participants 15-79 years of age who maintained an address within the same districts in Seoul, Republic of Korea, throughout the entire study period (between 2002 and 2010) and without a previous MDD diagnosis were analyzed. We used three district-specific exposure indices as measures of long-term PM2.5 exposure. Cox proportional hazards models adjusted for potential confounding factors and measured at district and individual levels were constructed. We further conducted stratified analyses according to underlying chronic diseases such as diabetes mellitus, cardiovascular disease, and chronic obstructive pulmonary disease.

RESULTS

The risk of MDD during the follow-up period (2008-2010) increased with an increase of 10 μg/m3 in PM2.5 in 2007 [hazard ratio (HR) = 1.44; 95% CI: 1.17, 1.78], PM2.5 between 2007 and 2010 (HR = 1.59; 95% CI: 1.02, 2.49), and 12-month moving average of PM2.5 until an event or censor (HR = 1.47; 95% CI: 1.14, 1.90). The association between long-term PM2.5 exposure and MDD was greater in participants with underlying chronic diseases than in participants without these diseases.

CONCLUSION

Long-term PM2.5 exposure increased the risk of MDD among the general population. Individuals with underlying chronic diseases are more vulnerable to long-term PM2.5 exposure.

CITATION

Kim KN, Lim YH, Bae HJ, Kim M, Jung K, Hong YC. 2016. Long-term fine particulate matter exposure and major depressive disorder in a community-based urban cohort. Environ Health Perspect 124:1547-1553; http://dx.doi.org/10.1289/EHP192.

Inflammatory insults and mental health consequences: does timing matter when it comes to depression?

It has become widely accepted that the immune system, and specifically increased levels of inflammation, play a role in the development of depression. However, not everyone with increased inflammation develops depression, and as with all other diseases, there are risk factors that may contribute to an increased vulnerability in certain individuals. One such risk factor could be the timing of an inflammatory exposure. Here, using a combination of PubMed, EMBASE, Ovid Medline and PsycINFO, we systematically reviewed whether exposure to medically related inflammation in utero, in childhood, and in adolescence, increases the risk for depression in adulthood. Moreover, we tried to determine whether there was sufficient evidence to identify a particular time point during the developmental trajectory in which an immune insult could be more damaging. While animal research shows that early life exposure to inflammation increases susceptibility to anxiety- and depressive-like behaviour, human studies surprisingly find little evidence to support the notion that medically related inflammation in utero and in adolescence contributes to an increased risk of developing depression in later life. However, we did find an association between childhood inflammation and later life depression, with most studies reporting a significantly increased risk of depression in adults who were exposed to inflammation as children. More robust clinical research, measuring direct markers of inflammation throughout the life course, is greatly needed to expand on, and definitively address, the important research questions raised in this review.

Host factors associated with serologic inflammatory markers assessed using multiplex assays

Chronic systemic inflammation contributes to the development of adverse health conditions, yet the influence of fixed and modifiable risk factors on many serologic biomarkers of inflammation remains largely unknown. Serum concentrations of twenty-three biomarkers, including C-reactive protein (CRP), cytokines (CXCL11, CXCL8, CXCL10, CCL2, CCL13, CCL4, CCL17, CXCL13, IL-10, IL-12p70, IL-6, TNF-α, IL-2, IFN-γ, IL-1β, GM-CSF, BAFF), and soluble immune receptors (sCD14, sIL-2Rα, sCD27, sgp130, sTNF-R2) were measured longitudinally using multiplexed immunometric assays in 250 HIV-uninfected men followed in the Multicenter AIDS Cohort Study (1984-2009). Generalized gamma regression was used to determine the statistical significance of factors associated with each biomarker. After accounting for age, race, and education, and for analysis of multiple biomarkers, higher concentrations of specific individual biomarkers were significantly (P<0.002) associated with hypertension, obesity, hepatitis C infection, stimulant use, and diabetes and lower concentrations with hypercholesterolemia. These associations should be taken into account in epidemiological studies of these biomarkers, and may provide potential targets for disease prevention and treatment.

Obesity, but not metabolic syndrome, negatively affects outcome in bipolar disorder

OBJECTIVE

Examine the effects of obesity and metabolic syndrome on outcome in bipolar disorder.

METHOD

The Comparative Effectiveness of a Second Generation Antipsychotic Mood Stabilizer and a Classic Mood Stabilizer for Bipolar Disorder (Bipolar CHOICE) study randomized 482 participants with bipolar disorder in a 6-month trial comparing lithium- and quetiapine-based treatment. Baseline variables were compared between groups with and without obesity, with and without abdominal obesity, and with and without metabolic syndrome respectively. The effects of baseline obesity, abdominal obesity, and metabolic syndrome on outcomes were examined using mixed effects linear regression models.

RESULTS

At baseline, 44.4% of participants had obesity, 48.0% had abdominal obesity, and 27.3% had metabolic syndrome; neither obesity, nor abdominal obesity, nor metabolic syndrome were associated with increased global severity, mood symptoms, or suicidality, or with poorer functioning or life satisfaction. Treatment groups did not differ on prevalence of obesity, abdominal obesity, or metabolic syndrome. By contrast, among the entire cohort, obesity was associated with less global improvement and less improvement in total mood and depressive symptoms, suicidality, functioning, and life satisfaction after 6 months of treatment. Abdominal obesity was associated with similar findings. Metabolic syndrome had no effect on outcome.

CONCLUSION

Obesity and abdominal obesity, but not metabolic syndrome, were associated with less improvement after 6 months of lithium- or quetiapine-based treatment.

Obesity and Its Potential Effects on Antidepressant Treatment Outcomes in Patients with Depressive Disorders: A Literature Review

Accumulating evidence regarding clinical, neurobiological, genetic, and environmental factors suggests a bidirectional link between obesity and depressive disorders. Although a few studies have investigated the link between obesity/excess body weight and the response to antidepressants in depressive disorders, the effect of weight on treatment response remains poorly understood. In this review, we summarized recent data regarding the relationship between the response to antidepressants and obesity/excess body weight in clinical studies of patients with depressive disorders. Although several studies indicated an association between obesity/excess body weight and poor antidepressant responses, it is difficult to draw definitive conclusions due to the variability of subject composition and methodological differences among studies. Especially, differences in sex, age and menopausal status, depressive symptom subtypes, and antidepressants administered may have caused inconsistencies in the results among studies. The relationship between obesity/excess body weight and antidepressant responses should be investigated further in high-powered studies addressing the differential effects on subject characteristics and treatment. Moreover, future research should focus on the roles of mediating factors, such as inflammatory markers and neurocognitive performance, which may alter the antidepressant treatment outcome in patients with comorbid obesity and depressive disorder.

Does Diet Matter? The Use of Polyunsaturated Fatty Acids (PUFAs) and Other Dietary Supplements in Inflammation-Associated Depression

An increasingly pertinent issue in psychiatry in recent years is that of the limitations of conventional antidepressants, which are not effective in a large number of patients with major depressive disorder (MDD). Coupled with emerging hypotheses about the role of inflammation in depression, it would appear that it is time to look for alternative treatments for these symptoms.This review will examine an emerging area in psychiatry, that of dietary supplements and the diet in general to treat depressive symptoms, and inflammation in depression. In particular, polyunsaturated fatty acids (PUFAs), probiotics and folic acid are three supplements that demonstrate the ability to target inflammation and other underlying systems in depression. While there is a definite need for more research in all these supplements to determine true efficacy, dosage and target populations, they can be used as mono- or adjunctive therapies to good effect, and show superior safety profiles when compared with more traditional alternatives.

An Overview of Links Between Obesity and Mental Health

The American Medical Association recently recognized obesity as both an illness and a leading cause of preventable death and chronic disease. This association is not only linked to physical health outcomes, however, as obesity has also been extensively associated with mental illness as well. Both obesity and severe mental illness decrease quality of life and are associated with an increase in disability, morbidity, and mortality, and when they occur together, these adverse health outcomes are magnified. Despite educational campaigns, increased awareness, and improved treatment options, the high prevalence of mental illness and comorbid obesity remains a serious problem. This review examines this overlap, highlighting clinical and biological factors that have been linked to this association in order to improve our understanding and help elucidate potential therapeutic avenues.

The association between obesity and fluid intelligence impairment is mediated by chronic low-grade inflammation

Published evidence suggests that obesity impairs cognition. Development of chronic low-grade inflammation (CLGI) represents the earliest consequence of obesity. The present study investigated the association between obesity and fluid intelligence impairment and assessed the potential mediating role of CLGI and psychological (depression/anxiety symptoms), lifestyle (exercise) and physiological (metabolic dysfunction indices) factors in this association. Clinically healthy participants (n 188), grouped as per BMI, underwent cognitive (General Ability Measure for Adults), psychological (Beck Depression Inventory-II and State-Trait Anxiety Inventory) and activity (Godin leisure-time physical activity) measurements. Biochemical parameters included the following: (a) indices of CLGI (high-sensitivity C-reactive protein, erythrocyte sedimentation rate and fibrinogen); (b) insulin resistance (Homeostasis Model Assessment of Insulin Resistance index); (c) adiposity (plasma adiponectin). An inverse association between elevated BMI and fluid intelligence was observed, with obese participants displaying significantly poorer performance compared with age-matched normal-weight peers. Structural equation modelling results were consistent with a negative impact of obesity on cognition that was mediated by CLGI. The results of the present study support the hypothesis that reduced general cognitive ability is associated with obesity, an adverse effect mainly mediated by obesity-associated activation of innate immunity.

Inflammation: a mechanism of depression?

In recent decades, major depression has become more prevalent and research has shown that immune activation and cytokine production may be involved. This review is mainly focused on the contribution of inflammation to depression. We first briefly introduce the inflammatory biomarkers of depression, then discuss the sources of cytokines in the brain, and finally describe the neuroimmunological mechanisms underlying the association between inflammation and depression.

Effect of a selective cyclooxygenase type 2 inhibitor celecoxib on depression associated with obesity in mice: an approach using behavioral tests

The biological mechanisms that link the development of depression to metabolic disorders such as obesity and diabetes remain ambiguous. In the present study the potential of a selective cyclooxygenase inhibitor celecoxib (15 mg/kg p.o.) was investigated in depression associated with obesity in mice. Behavioral tests used to assess depressive-like behavior were sucrose preference test, forced swim test (FST), tail suspension test (TST) and elevated plus maze (EPM). The basal locomotor score in obese mice was not altered. Furthermore, estimation of biochemical parameters was performed for plasma glucose, total cholesterol, triglycerides and total proteins. Escitalopram (10 mg/kg p.o.) served as reference standard drug. In the results, chronic treatment with celecoxib for 28 days significantly attenuated the behavioral alterations as indicated by increased the sucrose consumption, reduced the immobility time in FST and TST, increased the percent open arm time and entries in EPM in obese mice. In the biochemical parameters celecoxib significantly reversed the increased plasma glucose, total cholesterol, triglycerides and total proteins in obese mice. In conclusion, celecoxib exhibited potential antidepressant-like effect in depression associated with obesity, which to some extent is mediated by reversing the altered plasma glucose in obese mice.

Role of angiotensin II in the brain inflammatory events during experimental diabetes in rats

Hyperglycemia during diabetes is one of the causes of encephalopathy. However, diabetes causes chronic inflammatory complications and among them is peripheral neuropathy. Since, diabetes is one of the major risk factors for cerebrovascular disease, inflammatory process could take place in central nervous system (CNS). To test that hypothesis, experiments to determine inflammatory events in CNS during streptozotocin-induced diabetes were performed. Diabetes was induced by intravenous injection of streptozotocin (STZ). Brain angiotensin II (Ang II), monocyte/macrophage (ED-1 positive cells), CD8, the intercellular adhesion molecule-1 (ICAM-1), the lymphocyte function-associated antigen-1 (LFA-1) and superoxide anion were determined by hystochemical and immunohistochemical methods. Nitric oxide (NO), malondialdehyde (MDA) and catalase activity were measured in brain homogenates by enzymatic and biochemical methods. This research showed increased expressions of Ang II, ICAM-1, LFA-1 and CD8 positive cells in diverse zones of cerebrum and cerebellum of diabetic rats (week 8). Treatment of diabetic animals with losartan or enalapril reduced the expression of those molecules. Values of lipid peroxidation, nitrite content and superoxide anion expression remained similar to control rats. Only decreased activity of catalase was observed in diabetic animals, but losartan or enalapril failed to modify catalase activity. This study suggests the presence of Ang II-mediated brain inflammatory events in diabetes probably mediated by AT1 receptors.