Are medical comorbid conditions of bipolar disorder due to immune dysfunction?

Dysregulation of glucose metabolism since young adulthood increases the risk of cardiovascular diseases in patients with bipolar disorder

Aging patients with bipolar disorder (BD) are at a high risk of cardiovascular diseases (CVDs). However, few studies have directly examined the association between metabolic risks and CVDs in patients with BD across the lifespan. Therefore, the aim of this study was to determine lifetime metabolic risk factors for CVDs in patients with BD. We recruited BD-I patients who were more than 50 years old and had had at least one psychiatric hospitalization. Patients who had a cardiologist-confirmed CVD diagnosis (ICD-9 code 401-414) were assigned to the case group. Fifty-five cases were matched with 55 control patient without CVDs based on age and sex. Clinical data were obtained by retrospectively reviewing 30 years of hospital records. Compared to control subjects, a significantly higher proportion of cases had impaired fasting glucose between ages 31 and 40 (44.0% versus 17.4%, p = 0.046), diabetes mellitus between ages 41 and 50 (25.6% versus 8.6%, p = 0.054), and diabetes mellitus after age 51 (36.3% versus 12.7%, p = 0.005). No significant difference was found in overweight, obesity, or dyslipidemia. After adjusting for years of education, first episode as mania, and second generation antipsychotic use, lifetime diabetes mellitus remained a risk factor for CVDs (OR = 4.45, 95% CI = 1.89-10.66, p = 0.001). The findings suggest that glucose dysregulation across the adult age span is probably the major metabolic risk contributing to CVDs in patients with BD. Clinicians therefore have to notice the serum fasting glucose levels of BD patients since young adulthood.

Increased risk of bipolar disorder in patients with scabies: A nationwide population-based matched-cohort study

Both scabies and bipolar disorder (BD) are common and troublesome disorders. There are several similarities in both diseases: pruritus, a higher prevalence in crowded environments, and cytokine-mediated inflammatory processes in the pathophysiology. We conducted this nationwide population-based study to investigate the possible relationship between scabies and BD. Based on the National Health Insurance Research Database (NHIRD) of Taiwan, a total of 7096 patients with scabies were identified as a study group and 28,375 matched patients as a control. We tracked the patients in both groups for a 7-year period to identify those newly diagnosed with BD. The demographic characteristics and comorbidities of the patients were analyzed, and Cox proportional hazard regressions were performed to calculate the hazard ratio (HR) of BD. Of the 35,471 patients in this study, 183 (0.5%) patients with newly diagnosed BD were identified, with 58 (0.8%) from the scabies group and 125 (0.4%) from the control group. The patients with scabies had a higher risk of subsequent BD, with a crude hazard ratio of 1.86 and an adjusted hazard ratio of 1.55 (95% confidence interval: 1.12-2.09, P < 0.05). This study shows there is an increased risk for BD among patients with scabies. Immunopathology may contribute to this association.

Bipolar Disorder and Immune Dysfunction: Epidemiological Findings, Proposed Pathophysiology and Clinical Implications

Bipolar disorder (BD) is strongly associated with immune dysfunction. Replicated epidemiological studies have demonstrated that BD has high rates of inflammatory medical comorbidities, including autoimmune disorders, chronic infections, cardiovascular disease and metabolic disorders. Cytokine studies have demonstrated that BD is associated with chronic low-grade inflammation with further increases in pro-inflammatory cytokine levels during mood episodes. Several mechanisms have been identified to explain the bidirectional relationship between BD and immune dysfunction. Key mechanisms include cytokine-induced monoamine changes, increased oxidative stress, pathological microglial over-activation, hypothalamic-pituitary-adrenal (HPA) axis over-activation, alterations of the microbiome-gut-brain axis and sleep-related immune changes. The inflammatory-mood pathway presents several potential novel targets in the treatment of BD. Several proof-of-concept clinical trials have shown a positive effect of anti-inflammatory agents in the treatment of BD; however, further research is needed to determine the clinical utility of these treatments. Immune dysfunction is likely to only play a role in a subset of BD patients and as such, future clinical trials should also strive to identify which specific group(s) of BD patients may benefit from anti-inflammatory treatments.

Increased incidence of psychiatric disorders in immune-mediated inflammatory disease

OBJECTIVE

Although psychiatric comorbidity is known to be more prevalent in immune-mediated inflammatory diseases (IMID) than in the general population, the incidence of psychiatric comorbidity in IMID is less understood, yet incidence is more relevant for understanding etiology.

METHODS

Using population-based administrative (health) data, we conducted a retrospective cohort study over the period 1989-2012 in Manitoba, Canada. We identified 19,572 incident cases of IMID including 6119 persons with inflammatory bowel disease (IBD), 3514 persons with multiple sclerosis (MS), 10,206 persons with rheumatoid arthritis (RA), and 97,727 age-, sex- and geographically-matched controls. After applying validated case definitions, we estimated the incidence of depression, anxiety disorder, bipolar disorder and schizophrenia in each of the study cohorts. Using negative binomial regression models, we tested whether the incidence rate of psychiatric comorbidity was elevated in the individual and combined IMID cohorts versus the matched cohorts, adjusting for sex, age, region of residence, socioeconomic status and year.

RESULTS

The relative incidence of depression (incidence rate ratio [IRR] 1.71; 95%CI: 1.64-1.79), anxiety (IRR 1.34; 95%CI: 1.29-1.40), bipolar disorder (IRR 1.68; 95%CI: 1.52-1.85) and schizophrenia (IRR 1.32; 95%CI: 1.03-1.69) were elevated in the IMID cohort. Depression and anxiety affected the MS population more often than the IBD and RA populations.

CONCLUSIONS

Individuals with IMID, including IBD, MS and RA are at increased risk of psychiatric comorbidity. This increased risk appears non-specific as it is seen for all three IMIDs and for all psychiatric disorders studied, implying a common underlying biology for psychiatric comorbidity in those with IMID.

Risk factors for early cardiovascular mortality in patients with bipolar disorder

AIM

We attempted to determine risk factors, particularly pathophysiological changes, for early cardiovascular mortality in bipolar disorder (BD).

METHODS

A total of 5416 inpatients with bipolar I disorder were retrospectively followed through record linkage for cause of death. A total of 35 patients dying from cardiovascular disease (CVD; ICD 9: 401-443) before the age of 65 years were identified. Two living BD patients and two mentally healthy adults were matched with each deceased patient as control subjects according to age (±2 years), sex, and date (±3 years) of the final/index admission or the date of general health screening. Data were obtained through medical record reviews.

RESULTS

Eighty percent of CVD deaths occurred within 10 years following the index admission. Conditional logistic regression revealed that the variables most strongly associated with CVD mortality were the leukocyte count and heart rate on the first day of the index hospitalization, as the deceased BD patients were compared with the living BD controls. Systolic pressure on the first day of the index hospitalization can be substituted for heart rate as another risk factor for CVD mortality.

CONCLUSION

It is suggested that systemic inflammation and sympathetic overactivity during the acute phase of BD may be risk factors for early CVD mortality.

Medical comorbidity in bipolar disorder: The link with metabolic-inflammatory systems

BACKGROUND

Bipolar disorder (BD) is associated with chronic low-grade inflammation, several medical comorbidities and a decreased life expectancy. Metabolic-inflammatory changes have been postulated as one of the main links between BD and medical comorbidity, although there are few studies exploring possible mechanisms underlying this relationship. Therefore, the aims of the current narrative review were 1) synthesize the evidence for metabolic-inflammatory changes that may facilitate the link between medical comorbidity and BD and 2) discuss therapeutic and preventive implications of these pathways.

METHODS

The PubMed and Google Scholar databases were searched for relevant studies.

RESULTS

Identified studies suggested that there is an increased risk of medical comorbidities, such as autoimmune disorders, obesity, diabetes and cardiovascular disease in patients with BD. The association between BD and general medical comorbidities seems to be bidirectional and potentially mediated by immune dysfunction. Targeting the metabolic-inflammatory-mood pathway may potential yield improved outcomes in BD; however, further study is needed to determine which specific interventions may be beneficial.

LIMITATIONS

The majority of identified studies had cross-sectional designs, small sample sizes and limited measurements of inflammation.

CONCLUSIONS

Treatment and prevention of general medical comorbidities in mood disorders should include preferential prescribing of metabolically neutral agents and adjunctive lifestyle modifications including increased physical activity, improved diet and decreased substance abuse. In addition, the use of anti-inflammatory agents could be a relevant therapeutic target in future research.

Systematic assessment of environmental risk factors for bipolar disorder: an umbrella review of systematic reviews and meta-analyses

OBJECTIVES

The pathophysiology of bipolar disorder is likely to involve both genetic and environmental risk factors. In our study, we aimed to perform a systematic search of environmental risk factors for BD. In addition, we assessed possible hints of bias in this literature, and identified risk factors supported by high epidemiological credibility.

METHODS

We searched the Pubmed/MEDLINE, EMBASE and PsycInfo databases up to 7 October 2016 to identify systematic reviews and meta-analyses of observational studies that assessed associations between putative environmental risk factors and BD. For each meta-analysis, we estimated its summary effect size by means of both random- and fixed-effects models, 95% confidence intervals (CIs), the 95% prediction interval, and heterogeneity. Evidence of small-study effects and excess of significance bias was also assessed.

RESULTS

Sixteen publications met the inclusion criteria (seven meta-analyses and nine qualitative systematic reviews). Fifty-one unique environmental risk factors for BD were evaluated. Six meta-analyses investigated associations with a risk factor for BD. Only irritable bowel syndrome (IBS) emerged as a risk factor for BD supported by convincing evidence (k=6; odds ratio [OR]=2.48; 95% CI=2.35-2.61; P<.001), and childhood adversity was supported by highly suggestive evidence. Asthma and obesity were risk factors for BD supported by suggestive evidence, and seropositivity to Toxoplasma gondii and a history of head injury were supported by weak evidence.

CONCLUSIONS

Notwithstanding that several environmental risk factors for BD were identified, few meta-analyses of observational studies were available. Therefore, further well-designed and adequately powered studies are necessary to map the environmental risk factors for BD.

C-reactive protein: A differential biomarker for major depressive disorder and bipolar II disorder

Objectives We aimed to examine whether the C-reactive protein (CRP) level could be used to differentiate between major depressive disorder (MDD) and bipolar II disorder (BD II). Methods Ninety-six healthy controls, 88 BD II and 72 MDD drug-naïve patients in their major depressive episodes were enrolled. The fasting plasma level of high-sensitivity CRP was assessed at baseline and after treatment. Results The BD II patients presented significantly higher 17-item Hamilton Depression Rating Scale (HDRS) scores and CRP levels at baseline when adjustment for age, gender, and body mass index (P <  0.001 and P <  0.001, respectively). After treatment the CRP levels remained significantly different (P <  0.001), although the HDRS score was not significantly different between the BD II and MDD patients. A receiver-operating characteristic analysis showed that a baseline CRP level of 621.6 ng/mL could discriminate between BD II and MDD, with an area under the curve of 0.816 and a sensitivity and specificity of 0.699 and 0.882, respectively. Furthermore, the baseline CRP level greater than 621.6 ng/ml had 28.2 higher odds of a diagnosis of BD II (P <  0.001, 95% confidence interval: 10.96-72.35). Conclusions The level of CRP plays a role of biomarker to differentiate between MDD and BD II depression in both their depressed and euthymic state.

Obesity and obstetric complications are associated with rapid-cycling in Italian patients with bipolar disorder

BACKGROUND

Rapid cycling (RC) worsens the course of bipolar disorder (BD) being associated with poor response to pharmacotherapy. Previous studies identified clinical variables potentially associated with RCBD: however, in many cases, results were discordant or unreplicated. The present study was aimed to compare clinical variables between RC and non RC bipolar patients and to identify related risk factors.

METHODS

A sample of 238 bipolar patients was enrolled from 3 different community mental health centers. Descriptive analyses were performed on total sample, and patients were compared in terms of socio-demographic and clinical variables according to the presence of RC by multivariate analyses of variance (MANOVAs, continuous variables) or χ2 tests (qualitative variables). Binary logistic regression was performed to calculate odds ratios.

RESULTS

Twenty-eight patients (11.8%) had RC. The two groups were not different in terms of age, age at onset, gender distribution, type of family history, type of substance use disorder, history of antidepressant therapy, main antidepressant, psychotic symptoms, comorbid anxiety disorders, suicide attempts, thyroid diseases, diabetes, type of BD, duration of untreated illness, illness duration, duration of antidepressant treatment and GAF scores. In contrast, RC patients had more often a history of obstetric complications (p<0.05), obesity (p<0.05) and a trend to hypercholesterolemia (p=0.08). In addition, RC bipolar patients presented more frequently lifetime MDMA misuse (p<0.05) than patients without RC.

DISCUSSION

Findings from the present study seem to indicate that obesity and obstetric complications are risk factors for the development of RC in BD. In addition, lifetime MDMA misuse may be more frequent in RC bipolar patients.

Interleukin-1 β-targeted treatment strategies in inflammatory depression: toward personalized care

OBJECTIVES

It is unknown whether a cytokine signature may help the identification of subgroup of patient who would respond to personalized treatment. As interleukin-1 beta (Il-1β) seems to play a major role in mood disorder, a systematic review and meta-analysis of its potential role in major depressive disorder (MDD) was carried out.

METHODS

A systematic search was performed to identify appropriate MDD vs. control studies pertaining to Il-1β. Methodological quality and possible moderators were also assessed.

RESULTS

A total of 1922 studies were identified, and 53 articles were selected. Results showed an association between increased blood IL-1β and MDD in high-quality studies only. No association with age was found. No IL-1β gene-related polymorphisms has been associated with MDD. No effect of antidepressant on IL-1β level has been found, although the antidepressants investigated were various. Qualitative analyses indicate that MDD coupled to a history of childhood trauma may be a subgroup for IL-1β -targeted therapies. No difference in studies utilizing a stimulation method has been identified to date.

CONCLUSIONS

The present work has confirmed IL-1β as a biological marker of interest for innovative MDD treatments. However, further studies are needed to clarify the patients with MDD who may benefit from these therapies.

Bipolar disorder and diabetes mellitus: evidence for disease-modifying effects and treatment implications

BACKGROUND

Bipolar disorder refers to a group of chronic psychiatric disorders of mood and energy levels. While dramatic psychiatric symptoms dominate the acute phase of the diseases, the chronic course is often determined by an increasing burden of co-occurring medical conditions. High rates of diabetes mellitus in patients with bipolar disorder are particularly striking, yet unexplained. Treatment and lifestyle factors could play a significant role, and some studies also suggest shared pathophysiology and risk factors.

OBJECTIVE

In this systematic literature review, we explored data around the relationship between bipolar disorder and diabetes mellitus in recently published population-based cohort studies with special focus on the elderly.

METHODS

A systematic search in the PubMed database for the combined terms "bipolar disorder" AND "elderly" AND "diabetes" in papers published between January 2009 and December 2015 revealed 117 publications; 7 studies were large cohort studies, and therefore, were included in our review.

RESULTS

We found that age- and gender- adjusted risk for diabetes mellitus was increased in patients with bipolar disorder and vice versa (odds ratio range between 1.7 and 3.2).

DISCUSSION

Our results in large population-based cohort studies are consistent with the results of smaller studies and chart reviews. Even though it is likely that heterogeneous risk factors may play a role in diabetes mellitus and in bipolar disorder, growing evidence from cell culture experiments and animal studies suggests shared disease mechanisms. Furthermore, disease-modifying effects of bipolar disorder and diabetes mellitus on each other appear to be substantial, impacting both treatment response and outcomes.

CONCLUSIONS

The risk of diabetes mellitus in patients with bipolar disorder is increased. Our findings add to the growing literature on this topic. Increasing evidence for shared disease mechanisms suggests new disease models that could explain the results of our study. A better understanding of the complex relationship between bipolar disorder and diabetes mellitus could lead to novel therapeutic approaches and improved outcomes.

Immuno-psychiatry: an agenda for clinical practice and innovative research

BACKGROUND

The diagnostic scheme for psychiatric disorders is currently based purely on descriptive nomenclature given that biomarkers subtypes and clearly defined causal mechanisms are lacking for the vast majority of disorders. The emerging field of "immuno-psychiatry" has the potential to widen the exploration of a mechanism-based nosology, possibly leading to the discovery of more effective personalised treatment strategies.

DISCUSSION

Disturbances in immuno-inflammatory and related systems have been implicated in the aetiology, pathophysiology, phenomenology and comorbidity of several psychiatric disorders, including major mood disorders and schizophrenia. A fundamental challenge in their clinical management is to identify bio-signatures that might indicate risk, state, trait, prognosis or theragnosis. Here, we provide the rationale for a clinical and research agenda to refine future clinical practice and conceptual views, and to delineate pathways toward innovative treatment discovery.

CONCLUSION

The development of bio-signatures will allow clinicians to tailor interventions to the abovementioned biomarker subtypes - a major translational goal for research in this field.

Physical comorbidities increase the risk of psychiatric comorbidity in multiple sclerosis

BACKGROUND

Risk factors for psychiatric comorbidity in multiple sclerosis (MS) are poorly understood.

OBJECTIVE

We evaluated the association between physical comorbidity and incident depression, anxiety disorder, and bipolar disorder in a MS population relative to a matched general population cohort.

METHODS

Using population-based administrative data from Alberta, Canada we identified 9624 persons with MS, and 41,194 matches. Using validated case definitions, we estimated the incidence of depression, anxiety disorder, and bipolar disorder, and their association with physical comorbidities using Cox regression, adjusting for age, sex, socioeconomic status, and index year.

RESULTS

In both populations, men had a lower risk of depression and anxiety disorders than women, as did individuals who were ≥45 years versus <45 years at the index date. The risk of bipolar disorder declined with increasing age. The risks of incident depression (HR 1.92; 1.82-2.04), anxiety disorders (HR 1.52; 1.42-1.63), and bipolar disorder (HR 2.67; 2.29-3.11) were higher in the MS population than the matched population. These associations persisted essentially unchanged after adjustment for covariates including physical comorbidities. Multiple physical comorbidities were associated with psychiatric disorders in both populations.

CONCLUSION

Persons with MS are at increased risk of psychiatric comorbidity generally, and some physical comorbidities are associated with additional risk.

Peripheral blood mRNA expressions of stress biomarkers in manic episode and subsequent remission

Theoretical models of the neuroprogressive nature of bipolar disorder (BD) are based on the hypothesis that it is an accelerated aging disease, with the allostatic load playing a major role. Glucocorticoids, oxidative stress markers, inflammatory cytokines and neurotrophins play important roles in BD. The messenger ribonucleic acid (mRNA) expressions of brain-derived neurotrophic factor (BDNF), tissue plasminogen activator (tPA), glucocorticoid receptor (GR), heat shock protein 70 (HSP70), tumour necrosis factor-alpha (TNF-α) were examined in the peripheral blood of 20 adult male, drug-free BD patients during manic and remission periods and in 20 adult male, healthy controls. mRNA expression was measured using the quantitative real-time polymerase chain reaction (qRT-PCR). Compared to the controls, the expressions of BDNF and tPA mRNA were down-regulated in mania. In remission, BNDF and tPA mRNA levels increased, but they were still lower than those of the controls. Between mania and remission periods, only the change in mRNA levels of BDNF reached statistical significance. The results suggest that BDNF and tPA may be biomarkers of BD and that proteolytic conversion of BDNF may be important in the pathophysiology of BD. The change in BDNF levels between mania and remission could be adaptive and used to follow the progression of BD.

Bipolar Disorder and Inflammation

The pathophysiology of bipolar disorder (BD) remains poorly understood. Current psychopharmacologic treatments are often poorly tolerated and carry high rates of treatment resistance. Mounting evidence has suggested that innate immune system dysfunction may play a role in the pathophysiology of BD. Elevated proinflammatory cytokine levels have been identified. The innate immune system is a novel therapeutic target in BD. Lithium has been shown to have antiinflammatory properties. Further research is needed to establish the role of antiinflammatory agents in the treatment of BD; however, evidence from several clinical trials indicates that antiinflammatory agents may be incorporated into clinical practice soon.

Anti-inflammatory agents in the treatment of bipolar depression: a systematic review and meta-analysis

OBJECTIVE

Inflammation has been implicated in the risk, pathophysiology, and progression of mood disorders and, as such, has become a target of interest in the treatment of bipolar disorder (BD). Therefore, the objective of the current qualitative and quantitative review was to determine the overall antidepressant effect of adjunctive anti-inflammatory agents in the treatment of bipolar depression.

METHODS

Completed and ongoing clinical trials of anti-inflammatory agents for BD published prior to 15 May 15 2015 were identified through searching the PubMed, Embase, PsychINFO, and Clinicaltrials.gov databases. Data from randomized controlled trials (RCTs) assessing the antidepressant effect of adjunctive mechanistically diverse anti-inflammatory agents were pooled to determine standard mean differences (SMDs) compared with standard therapy alone.

RESULTS

Ten RCTs were identified for qualitative review. Eight RCTs (n = 312) assessing adjunctive nonsteroidal anti-inflammatory drugs (n = 53), omega-3 polyunsaturated fatty acids (n = 140), N-acetylcysteine (n = 76), and pioglitazone (n = 44) in the treatment of BD met the inclusion criteria for quantitative analysis. The overall effect size of adjunctive anti-inflammatory agents on depressive symptoms was -0.40 (95% confidence interval -0.14 to -0.65, p = 0.002), indicative of a moderate and statistically significant antidepressant effect. The heterogeneity of the pooled sample was low (I² = 14%, p = 0.32). No manic/hypomanic induction or significant treatment-emergent adverse events were reported.

CONCLUSIONS

Overall, a moderate antidepressant effect was observed for adjunctive anti-inflammatory agents compared with conventional therapy alone in the treatment of bipolar depression. The small number of studies, diversity of agents, and small sample sizes limited interpretation of the current analysis.

Extracellular matrix proteins matrix metallopeptidase 9 (MMP9) and soluble intercellular adhesion molecule 1 (sICAM-1) and correlations with clinical staging in euthymic bipolar disorder

OBJECTIVES

Matrix metallopeptidase 9 (MMP9) and soluble intercellular adhesion molecule 1 (sICAM-1) are both involved in the restructuring of connective tissues. Evidence also implicates MMP9 and sICAM in cardiovascular and neoplastic diseases, where blood levels may be a marker of disease severity or prognosis. In individuals with bipolar disorder (BD), higher risk for cardiovascular illness has been extensively reported.

METHODS

The aim of this investigation was to measure and compare peripheral levels of serum MMP9 and sICAM in adults with euthymic BD and healthy controls (HC). Furthermore, we focussed on correlations with illness severity and metabolic parameters.

RESULTS

MMP9 levels among the BD sample (n = 112) were significantly higher than among the HC (n = 80) (MMP9: F = 9.885, p = 0.002, η(2)  = 0.058) after controlling for confounding factors. Patients with BD in a later, progressive stage of disease showed significantly higher MMP9 as well as sICAM-1 levels compared to patients with BD in an earlier stage of disease (MMP9: F = 5.8, p = 0.018, η(2)  = 0.054; sICAM-1: F = 5.6, p = 0.020, η(2)  = 0.052). Correlation analyses of cognitive measures revealed a negative association between performance on the d2 Test of Attention and MMP9 (r = -0.287, p = 0.018) in the BD sample. Despite the sample being euthymic (i.e., according to conventional criteria) at the time of analysis, we found significant correlations between MMP9 as well as sICAM-1 and subthreshold depressive/hypomanic symptoms.

CONCLUSIONS

A collection of disparate findings herein point to a role of MMP9 and cICAM-1 in the patho-progressive process of BD: the increased levels of serum MMP9 and sICAM-1, the correlation between higher levels of these parameters, progressive stage, and cognitive dysfunction in BD, and the positive correlation with subthreshold symptoms. As sICAM-1 and MMP9 are reliable biomarkers of inflammatory and early atherosclerotic disease, these markers may provide indications of the presence of occult cardiovascular disease in this highly at-risk population.

Towards a blood-based diagnostic panel for bipolar disorder

BACKGROUND

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

METHODS AND FINDINGS

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

CONCLUSIONS

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

Associations between comorbid health conditions and the use of mental health services among adults with bipolar disorder

Using a nationally representative sample, this study examined to what extent the number of comorbid health conditions was associated with various mental health service utilization among people with bipolar disorder. The results of logistic regression models indicate that a greater number of comorbid medical conditions were associated with higher odds of using specialty mental health service, while they were not associated with utilization of services provided by general health care providers. The type of bipolar disorder, functional impairment, and marital status were found to be associated with the use of a specialty service, while ethnicity was the only covariate significantly related to general health care use.

Inflammation as a neurobiological substrate of cognitive impairment in bipolar disorder: Evidence, pathophysiology and treatment implications

BACKGROUND

Bipolar disorder (BD) has been associated with cognitive impairment during depressed, manic and euthymic periods. Inflammation has been shown to be involved in the pathophysiology of BD and cognitive impairment.

METHODS

For this systematic review, the MEDLINE/PubMed, Embase, Google Scholar and ClinicalTrials.gov databases were searched for relevant articles assessing the association between cognitive function and inflammatory markers in BD subjects. A discussion of potential mechanisms and therapeutic implications is also included to provide further context to the subject matter.

RESULTS

Eight studies, including a total of 555 BD subjects, assessing the association between cognitive function and inflammatory markers were identified. Cognitive dysfunction was associated with elevated levels of pro-inflammatory markers YKL40, IL-6, sCD40L, IL-1Ra, hsCRP and TNF-α. Mechanistically, elevation in inflammatory cytokines alters monoamine levels leading to cognitive and affective dysfunction. Neuro-inflammation, manifesting as microglial activation, leads to increased oxidative stress, pathologic synaptic pruning and impaired neuroplasticity in key brain regions sub-serving mood and cognition. Immune dysfunction also activates the hypothalamic-pituitary-adrenal (HPA) axis leading to hypercortisolemia and metabolic dysfunction, further promoting neuronal dysfunction. Anti-inflammatory agents are therefore currently being investigated in the treatment of BD and appear to exert an antidepressant effect; however, cognitive outcomes have yet to be reported.

CONCLUSION

Several studies suggest that immune dysfunction is associated with cognitive impairment in BD. Several neurobiological pathways have been identified whereby immune dysfunction may promote cognitive impairment in BD. Future investigations of anti-inflammatory agents targeting cognitive function as a treatment outcome are merited.

Is bipolar disorder associated with accelerating aging? A meta-analysis of telomere length studies

BACKGROUND

Bipolar disorder (BD) is associated with a reduced life expectancy compared to the general population mainly due to a high prevalence of comorbid somatic illnesses. A model of accelerated aging has been proposed as a potential explanation to these epidemiological findings. Nevertheless, studies measuring telomere length (TL) in patients with BD compared to healthy controls have provided mixed results.

OBJECTIVE

To compare TL between BD patients and healthy controls, and to search for potential modeP<rators for observed differences.

METHODS

We performed a systematic review and meta-analysis of original studies comparing TL in patients with BD vs. healthy controls published up to February 24th, 2015 in main electronic databases. Heterogeneity was explored through meta-regression and subgroup analysis.

RESULTS

Seven studies met inclusion criteria (N=1115). There was no difference in TL between participants with BD and healthy controls (Hedges's g=-0.012; 95% CI=-0.418 to 0.393, P=0.952). There was no evidence for publication bias. Heterogeneity was high (I(2)=89.65%). In meta-regression analyses, the percentage of females in healthy control samples (P=0.04) and the methodological quality of included studies (P<0.001) emerged as significant moderators, while subgroup analyses suggest that the type of assay employed to measure TL and age- and gender-matching of BD and HC participants may contribute to heterogeneity.

CONCLUSIONS

Telomere length does not differ between participants with BD vs. healthy controls; this finding does not support the view of BD as an illness associated with accelerated cellular aging. However, more studies controlling for potential confounders are necessary.