Relationship of cerebrospinal fluid glucose metabolites to MRI deep white matter hyperintensities and treatment resistance in bipolar disorder patients

Cerebral Glucose Metabolism following TBI: Changes in Plasma Glucose, Glucose Transport and Alternative Pathways of Glycolysis-A Translational Narrative Review

Traumatic brain injury (TBI) is a major public health concern with significant consequences across various domains. Following the primary event, secondary injuries compound the outcome after TBI, with disrupted glucose metabolism emerging as a relevant factor. This narrative review summarises the existing literature on post-TBI alterations in glucose metabolism. After TBI, the brain undergoes dynamic changes in brain glucose transport, including alterations in glucose transporters and kinetics, and disruptions in the blood-brain barrier (BBB). In addition, cerebral glucose metabolism transitions from a phase of hyperglycolysis to hypometabolism, with upregulation of alternative pathways of glycolysis. Future research should further explore optimal, and possibly personalised, glycaemic control targets in TBI patients, with GLP-1 analogues as promising therapeutic candidates. Furthermore, a more fundamental understanding of alterations in the activation of various pathways, such as the polyol and lactate pathway, could hold the key to improving outcomes following TBI.

The non-linear correlation between the volume of cerebral white matter lesions and incidence of bipolar disorder: A secondary analysis of data from a cross-sectional study

Cerebral white matter lesions (WML) are major risk factors for bipolar disorder (BD). However, studies on the association between cerebral WML volume and BD risk are limited. This study aimed to investigate the relationship between cerebral WML volume and BD incidence. This is a secondary retrospective analysis of patients (N = 146, 72 males, 74 females, mean age = 41.77 years) who have previously undergone magnetic resonance imaging examinations. Information was obtained from the Dryad database. Univariate analysis, piecewise linear regression model, and multivariable logistic regression model were used for statistical analysis. A non-linear relationship was recognized between the cerebral WML volume and BD incidence, in which the inflection point of the WML volume was 6,200 mm³. The effect sizes and confidence intervals on the left and right sides of the emphasis point were 1.0009 (1.0003, 1.0015) and 0.9988 (0.9974, 1.0003), respectively. Subgroup analysis (WML volume < 6,200 mm³) showed that the cerebral WML volume (for 0.1 mm³ increase) was positively related to the BD incidence (OR = 1.11, 95% confidence interval [CI] (1.03, 1.21)). Here we show that the cerebral WML volume is positively and non-linearly correlated to the BD risk. Volumetric analysis of WML provide a better understanding of the association between WML and the BD risk, and thereby the pathophysiological mechanisms of BD.

Graphical abstract

A non-linear relationship between the volume of cerebral white matter lesions (WML) and bipolar disorder (BD) incidence is shown. The cerebral WML volume is positively and non-linearly correlated to the BD risk. The correlation is stronger when the cerebral WML volume was <6,200 mm³.Graphical AbstractA non-linear relationship between the volume of cerebral white matter lesions and bipolar disorder incidence is shown after adjusting for age; sex; lithium, atypical antipsychotic, antiepileptic, and antidepressant drug use; BMI; migraine; smoking; hypertension; diabetes mellitus; substance and alcohol dependency; and anxiety disorder.

Elevated cerebrospinal fluid glucose levels and diabetes mellitus are associated with activation of the neurotoxic polyol pathway

AIMS/HYPOTHESIS

During hyperglycaemia, some glucose bypasses glycolysis and is metabolised via the potentially neurotoxic polyol pathway, in which glucose is metabolised to sorbitol and fructose. Increased polyol concentrations have been demonstrated in the cerebrospinal fluid (CSF) of neurological patients with and without diabetes mellitus. However, polyol levels in patients without evident neurological abnormalities have not been investigated so far. The aim of this study was to determine CSF polyol concentrations in patients without major neurological disease with normal or elevated CSF glucose concentrations.

METHODS

This observational cohort study used CSF and plasma analyses, as well as clinical data, from 30 participants of the Anaesthetic Biobank of Cerebrospinal Fluid study. Biomaterial was collected from adult patients scheduled for elective surgery under spinal anaesthesia. CSF polyol concentrations were measured by GC/flame ionisation detector in ten patients with normal CSF glucose levels (group 1), ten patients with elevated CSF glucose levels (group 2) and ten patients with elevated CSF glucose levels and type 2 diabetes (group 3). We compared the concentrations of plasma glucose, CSF glucose, sorbitol and fructose, and CSF polyol/glucose ratios between the three groups, and determined the correlation between plasma glucose levels and CSF glucose, sorbitol and fructose levels.

RESULTS

Groups 2 and 3 had significantly higher CSF fructose levels compared with group 1 (p=0.036 and p<0.001, respectively). Group 3 showed significant differences compared with groups 1 and 2 for CSF sorbitol (p<0.001 and 0.036, respectively). Moreover, patients with diabetes had a significantly higher CSF sorbitol/glucose ratio compared with patients without diabetes. There was a strong positive correlation between plasma glucose and CSF glucose, sorbitol and fructose. Finally, age, sex, CSF/plasma albumin ratio and preoperative cognitive function scores were significantly correlated with plasma glucose and CSF glucose, sorbitol and fructose levels.

CONCLUSIONS/INTERPRETATION

Hyperglycaemia causes a proportional increase in polyol concentrations in CSF of patients without major neurological disease. Furthermore, this study provides the first indication of upregulation of the cerebral polyol pathway in patients with diabetes without evident neurological abnormalities.

Fructose and Uric Acid as Drivers of a Hyperactive Foraging Response: A Clue to Behavioral Disorders Associated with Impulsivity or Mania?

Several behavioral disorders, including attention deficit hyperactivity disorder (ADHD), bipolar disorder, and aggressive behaviors are linked with sugar intake and obesity. The reason(s) for this association has been unclear. Here we present a hypothesis supporting a role for fructose, a component of sugar and high fructose corn syrup (HFCS), and uric acid (a fructose metabolite), in increasing the risk for these behavioral disorders. Recent studies have shown that the reason fructose intake is strongly associated with development of metabolic syndrome is that fructose intake activates an evolutionary-based survival pathway that stimulates foraging behavior and the storage of energy as fat. While modest intake may aid animals that would like to store fat as a protective response from food shortage or starvation, we propose that high intake of sugar and HFCS causes a hyperactive foraging response that stimulates craving, impulsivity, risk taking and aggression that increases the risk for ADHD, bipolar disease and aggressive behavior. High glycemic carbohydrates and salty foods may also contribute as they can be converted to fructose in the body. Some studies suggest uric acid produced during fructose metabolism may mediate some of these effects. Chronic stimulation of the pathway could lead to desensitization of hedonic responses and induce depression. In conclusion, a hyperactive foraging response driven by high glycemic carbohydrates and sugars may contribute to affective disorders.

Comparison of amide proton transfer imaging and magnetization transfer imaging in revealing glioma grades and proliferative activities: a histogram analysis

PURPOSE

Comprehensive understanding glioma metabolic characters is of great help for patient management. We aimed to compare amide proton transfer imaging (APTw) and magnetization transfer imaging (MT) in predicting glioma malignancy and reflecting tumor proliferation.

METHODS

Thirty low-grade gliomas (LGGs) and 39 high-grade gliomas (HGGs) were prospectively included, of which 58 samples Ki-67 levels were quantified. Anatomical MRI, APTw, and MT were scanned, and magnetization transfer ratio (MTR) and asymmetric magnetic transfer ratio at 3.5 ppm (MTR_asym(3.5ppm)) were calculated. ROIs were semi-automatically drawn with ImageJ, from which histogram features, including 5th, 25th, 50th, mean, 70th, 90th, and 95th percentiles were extracted. The independent t test was used to test differences in LGGs and HGGs, and correlations between histogram features and tumor grades, Ki-67 were revealed by Spearman's rank or Pearson's correlation analysis.

RESULTS

The maximum correlation coefficient (R) values of APTw were 0.526 (p < 0.001) with tumor grades and 0.397 (p < 0.001) with Ki-67 at 90th percentiles, while only 5th and 25th percentiles of MT significantly correlated with tumor grades. Moreover, APTw features were significantly different in LGGs and HGGs, except 5th percentile. The most significantly different feature was 95th percentile, providing the excellent AUC of 0.808. However, the best feature in MTR was 5th percentiles with AUC of 0.703. Combing 5th and 95th of APTw achieved highest AUC Of 0.837.

CONCLUSIONS

Both APTw and MT provide quantitative information for tumor metabolite imaging. However, APTw supplys more specific information in reflecting glioma biological behaviors than MT, and well differentiates glioma malignancy.

Prevalence of white matter hyperintensities is not elevated in a large sample of adolescents and young adults with bipolar disorder

OBJECTIVE

The increased prevalence rate of white matter hyperintensities is one of the most consistently reported brain abnormalities in adults with bipolar disorder. However, findings in children and adolescents with bipolar disorder are less consistent. Prior studies have been constrained by small sample sizes and/or poor age- and sex-matching of healthy controls. We examined this topic in the largest sample of adolescents with bipolar disorder to date.

METHODS

T2-weighted 3-Tesla magnetic resonance imaging data were acquired for 83 adolescents with bipolar disorder diagnosed via the Kiddie Schedule for Affective Disorders and the Schizophrenia, Present and Lifetime version semi-structured interview and 64 age- and sex-matched healthy controls. All acquired scans were examined by neuroradiologists and the presence or absence of white matter hyperintensities was determined for each participant.

RESULTS

The prevalence of white matter hyperintensities did not differ between adolescents with bipolar disorder (13.3%) and controls (21.9%; χ2 = 1.90; p = 0.168).

CONCLUSION

In contrast to the study hypothesis, the prevalence of white matter hyperintensities was not higher in adolescents with bipolar disorder than controls. The large sample size and good matching for age and sex bolster the reliability of this negative finding. Future studies are warranted to evaluate the prevalence, incidence, and predictors of white matter hyperintensities in early-onset bipolar disorder prospectively.

Personalized and precision medicine as informants for treatment management of bipolar disorder

DSM-5 diagnostic categories, defined by a set of psychopathological symptoms are heterogeneous conditions that may include different biological entities, with distinct etiopathogenesis, different courses and requiring different treatment management. For bipolar disorder the major evidences for this lack of validity are the long paths before a proper diagnosis, the inconsistence of treatment guidelines, the long phases of pharmacological adjustment and the low average of long-term treatment response rates. Personalized medicine for mental disorders aims to couple established clinical-pathological indexes with new molecular profiling to create diagnostic, prognostic and therapeutic strategies precisely tailored to each patient. Regarding bipolar disorder, the clinical history and presentation are still the most reliable markers in stratifying patients and guiding therapeutic management, despite the research goes to great lengths to develop new neuropsychological or biological markers that can reliably predict individual therapy effectiveness. We provide an overview of the advancements in personalized medicine in bipolar disorder, with particular attention to how psychopathology, age at onset, comorbidity, course and staging, genetic and epigenetic, imaging and biomarkers can influence treatment management and provide an integration to the conventional treatment guidelines. This approach may offer a new and rational path for the development of treatments for targeted subgroups of patients with bipolar disorder.

Age-related deficits in intracortical myelination in young adults with bipolar disorder type I

BACKGROUND

Previous studies have implicated white-matter-related changes in the pathophysiology of bipolar disorder. However, most of what is known is derived from in vivo subcortical white-matter imaging or postmortem studies. In this study, we investigated whole-brain intracortical myelin (ICM) content in people with bipolar disorder type I and controls.

METHODS

Between Sept. 1, 2014, and Jan. 31, 2017, we used a 3 T General Electric scanner to collect T1-weighted images in 45 people with bipolar disorder type I and 60 controls aged 17 to 45 years using an optimized sequence that was sensitive to ICM content. We analyzed images using a surfacebased approach. We used general linear models with quadratic age terms to examine the signal trajectory of ICM across the age range.

RESULTS

In healthy controls, the T1-weighted signal followed an inverted-U trajectory over age; in people with bipolar disorder type I, the association between ICM and age followed a flat trajectory (p < 0.05, Bonferroni corrected). Exploratory analyses showed that ICM signal intensity was associated with duration of illness, age of onset, and anticonvulsant and antipsychotic use in people with bipolar disorder type I (p < 0.05, uncorrected).

LIMITATIONS

Because of the cross-sectional nature of the study, we were unable to comment on whether the effects were due to dysmyelination or demyelination in bipolar disorder.

CONCLUSION

This foundational study is, to our knowledge, the first to show global age-related deficits in ICM maturation throughout the cortex in bipolar disorder. Considering the impact of myelination on the maintenance of neural synchrony and the integrity of neural connections, this work may help us better understand the cognitive and behavioural deficits seen in bipolar disorder.

MRI features of clinical outcome in bipolar disorder: A selected review: Special Section on "Translational and Neuroscience Studies in Affective Disorders". Section Editor, Maria Nobile MD, PhD. This Section of JAD focuses on the relevance of translational and neuroscience studies in providing a better understanding of the neural basis of affective disorders. The main aim is to briefly summaries relevant research findings in clinical neuroscience with particular regards to specific innovative topics in mood and anxiety disorders

BACKGROUND

Bipolar disorder (BD) is a severe and disabling mental illness, which is characterized by selective gray matter (GM) and white matter (WM) brain alterations, as observed by several imaging studies. However, the clinical course of the disease is uncertain and can vary across BD patients, with some having a benign course and others a severe disability. In this perspective, magnetic resonance imaging (MRI) can help identifying biological markers of worse prognosis.

METHODS

The present selected review aimed at summarizing structural MRI (sMRI) studies exploring the correlation between brain morphology and features of clinical outcome, which could include treatment response, cognitive impairment and global functioning.

RESULTS

Overall, the results from the reviewed sMRI studies reported that WM hyperintensities and GM volume reductions, mainly in fronto-limbic areas, correlate with worse outcome in BD. However, the selected outcome measures vary across studies, thus these observations cannot be conclusive.

LIMITATIONS

Heterogeneity across studies and inconsistency on the outcome measures adopted limit the conclusion of the present review. Absence of widely shared definitions of outcome should be object of further research on BD in order to indicate more stable features of illness course.

CONCLUSIONS

In summary, WM hyperintensities and fronto-temporo-limbic GM alterations may be potential indices of worse outcome in BD patients, particularly in terms of illness severity and progression. The identification of stable markers of prognosis can help the clinicians in selecting subgroups of bipolar patients who need specific treatment to preserve cognitive / psychosocial functioning, in the light of personalized approaches. To further characterize outcome in BD, future sMRI studies should a) longitudinally investigate patients with either poor or good course of the disease, and b) correlate neuroimaging measures with clinical, cognitive and genetic markers.

Perturbational Profiling of Metabolites in Patient Fibroblasts Implicates α-Aminoadipate as a Potential Biomarker for Bipolar Disorder

Many studies suggest the presence of aberrations in cellular metabolism in bipolar disorder. We studied the metabolome in bipolar disorder to gain insight into cellular pathways that may be dysregulated in bipolar disorder and to discover evidence of novel biomarkers. We measured polar and nonpolar metabolites in fibroblasts from subjects with bipolar I disorder and matched healthy control subjects, under normal conditions and with two physiologic perturbations: low-glucose media and exposure to the stress-mediating hormone dexamethasone. Metabolites that were significantly different between bipolar and control subjects showed distinct separation by principal components analysis methods. The most statistically significant findings were observed in the perturbation experiments. The metabolite with the lowest p value in both the low-glucose and dexamethasone experiments was α-aminoadipate, whose intracellular level was consistently lower in bipolar subjects. Our study implicates α-aminoadipate as a possible biomarker in bipolar disorder that manifests under cellular stress. This is an intriguing finding given the known role of α-aminoadipate in the modulation of kynurenic acid in the brain, especially as abnormal kynurenic acid levels have been implicated in bipolar disorder.

Genome-wide association study of periweaning failure-to-thrive syndrome (PFTS) in pigs

Porcine periweaning-failure-to-thrive syndrome (PFTS) is a condition that affects newly weaned piglets. It is characterised by a progressive debilitation leading to death, in the absence of infectious, nutritional, management or environmental factors. In this study, we present the first report of PFTS in South America and the results of a genome-wide association study to identify the genetic markers associated with the appearance of this condition in a crossbred swine population. Four chromosomal regions were associated with PFTS predisposition, one located on SSCX, one on SSC8, and the two other regions on SSC14. Regions on SSC8 and SSC14 harbour important functional candidate genes involved in human depression and might have an important role in PFTS. Our findings contribute to the increasing knowledge about this syndrome, which has been investigated since 2007, and to the identification of the aetiology of this disease.

The impact of periventricular white matter lesions in patients with bipolar disorder type I

INTRODUCTION

White matter hyperintensities (WMHs) are one the most common neuroimaging findings in patients with bipolar disorder (BD). It has been suggested that WMHs are associated with impaired insight in schizophrenia and schizoaffective patients; however, the relationship between insight and WMHs in BD type I has not been directly investigated.

METHODS

Patients with BD-I (148) were recruited and underwent brain magnetic resonance imaging (MRI). Affective symptoms were assessed using Young Mania Rating Scale (YMRS) and Hamilton Depression Rating Scale (HDRS17); the presence of impaired insight was based on the corresponding items of YMRS and HDRS17.

RESULTS

Multiple punctate periventricular WMHs (PWMHs) and deep WMHs (DWMHs) were observed in 49.3% and 39.9% of the cases, respectively. Subjects with lower insight for mania had significantly more PWMHs (54.6% vs 22.2%; p < 0.05) when compared to BD-I patients with higher insight for mania. The presence of PWMHs was independently associated with lower insight for mania: patients who denied illness according to the YMRS were 4 times more likely to have PWMHs (95% CI: 1.21/13.42) than other patients.

CONCLUSIONS

Impaired insight in BD-I is associated with periventricular WMHs. The early identification of BD-I subjects with PWMHs and impaired insight may be crucial for clinicians.

Cerebral White Matter Lesions and Affective Episodes Correlate in Male Individuals with Bipolar Disorder

Background

Cerebral white matter lesions (WML) have been found in normal aging, vascular disease and several neuropsychiatric conditions. Correlations of WML with clinical parameters in BD have been described, but not with the number of affective episodes, illness duration, age of onset and Body Mass Index in a well characterized group of euthymic bipolar adults. Herein, we aimed to evaluate the associations between bipolar course of illness parameters and WML measured with volumetric analysis.

Methods

In a cross-sectional study 100 euthymic individuals with BD as well as 54 healthy controls (HC) were enrolled to undergo brain magnetic resonance imaging using 3T including a FLAIR sequence for volumetric assessment of WML-load using FSL-software. Additionally, clinical characteristics and psychometric measures including Structured Clinical Interview according to DSM-IV, Hamilton-Depression, Young Mania Rating Scale and Beck’s Depression Inventory were evaluated.

Results

Individuals with BD had significantly more (F = 3.968, p < .05) WML (Mdn = 3710mm3; IQR = 2961mm3) than HC (Mdn = 2185mm3; IQR = 1665mm3). BD men (Mdn = 4095mm3; IQR = 3295mm3) and BD women (Mdn = 3032mm3; IQR = 2816mm3) did not significantly differ as to the WML-load or the number and type of risk factors for WML. However, in men only, the number of manic/hypomanic episodes (r = 0.72; p < .001) as well as depressive episodes (r = 0.51; p < .001) correlated positively with WML-load.

Conclusions

WML-load strongly correlated with the number of manic episodes in male BD patients, suggesting that men might be more vulnerable to mania in the context of cerebral white matter changes.

Metabolic syndrome and childhood trauma: Also comorbidity and complication in mood disorder

Studies for prevalence and causal relationship established that addressing comorbidities of mental illnesses with medical disease will be another revolution in psychiatry. Increasing number of evidence shows that there is a bidirectional connection between mood disorders and some medical diseases. Glucocorticoid/insulin signal mechanisms and immunoenflammatory effector systems are junction points that show pathophysiology between bipolar disorder and general medical situations susceptible to stress. A subgroup of mood disorder patients are under risk of developing obesity and diabetes. Their habits and life styles, genetic predisposition and treatment options are parameters that define this subgroup. Medical disease in adults had a significant relationship to adverse life experiences in childhood. This illustrates that adverse experiences in childhood are related to adult disease by two basic etiologic mechanisms: (1) conventional risk factors that actually are compensatory behaviors, attempts at self-help through the use of agents and foods; and (2) the effects of chronic stress.

White matter alterations in bipolar disorder: potential for drug discovery and development

OBJECTIVES

Brain white matter (WM) alterations have recently emerged as potentially relevant in bipolar disorder. New techniques such as diffusion tensor imaging allow precise exploration of these WM microstructural alterations in bipolar disorder. Our objective was to critically review WM alterations in bipolar disorder, using neuroimaging and neuropathological studies, in the context of neural models and the potential for drug discovery and development.

METHODS

We conducted a systematic PubMed and Google Scholar search of the WM and bipolar disorder literature up to and including January 2013.

RESULTS

Findings relating to WM alterations are consistent in neuroimaging and neuropathology studies of bipolar disorder, especially in regions involved in emotional processing such as the anterior frontal lobe, corpus callosum, cingulate cortex, and in fronto-limbic connections. Some of the structural alterations are related to genetic risk factors for bipolar disorder and may underlie the dysfunctional emotional processing described in recent neurobiological models of bipolar disorder. Medication effects in bipolar disorder, from lithium and other mood stabilizers, might impact myelinating processes, particularly by inhibition of glycogen synthase kinase-3 beta.

CONCLUSIONS

Pathways leading to WM alterations in bipolar disorder represent potential targets for the development and discovery of new drugs. Myelin damage in bipolar disorder suggests that the effects of existing pro-myelinating drugs should also be evaluated to improve our understanding and treatment of this disease.

Higher pretreatment 5-HT1A receptor binding potential in bipolar disorder depression is associated with treatment remission: a naturalistic treatment pilot PET study

Bipolar disorder is a major cause of disability and a high risk for suicide. The pathophysiology of the disorder remains largely unknown. Medication choice for bipolar depression patients involves trial and error. Our group reported previously that brain serotonin 1A (5-HT(1A)) receptor binding measured by positron emission tomography (PET) is higher in bipolar depression. We now investigated whether pretreatment 5-HT(1A) levels correlates with antidepressant medication outcome. Forty-one medication-free DSM-IV diagnosed, bipolar patients in a major depressive episode had brain PET scans performed using [(11)C]WAY-100635 and a metabolite corrected arterial input function. The patients then received naturalistic psychopharmacologic treatment as outpatients and a follow up Hamilton Depression Rating Scale (HDRS) after 3 months of treatment. Patients with 24 item HDRS scores less than 10 were considered to have remitted. A linear mixed effects model was used to compare BP(F) (binding potential, proportional to the total number of available receptors) in 13 brain regions of interest between remitters and nonremitters. Thirty-four patients completed 3 months of treatment and ratings; 9 had remitted. Remitters and nonremitters did not differ in age, sex, or recent medication history with serotonergic medications. Remitters had higher [(11)C]WAY-100635 BP(F) across all brain regions compared with nonremitters (P = 0.02). Higher pretreatment brain 5-HT(1A) receptor binding was associated with remission after 3 months of pharmacological treatment in bipolar depression. Prospective treatment studies are warranted to determine whether this test predicts outcome of specific types of treatment.

Total white matter hyperintensity volume in bipolar disorder patients and their healthy relatives

OBJECTIVES

White matter hyperintensities (WMH) are more common in subjects with bipolar disorder (BP) than in healthy subjects (HS). Few studies have examined the effect of the diagnostic type of bipolar illness on WMH burden, and none have approached this question through a direct measurement of the volume of affected white matter in relationship to familiality. In this pilot study, we utilized a volumetric measurement of WMH to investigate the relationship between the total volume of WMH and the familiality and type of BP.

METHODS

Forty-five individuals with bipolar I disorder (BP-I) with psychotic features, BP-I without psychotic features, or bipolar II disorder (BP-II), seven of their unaffected relatives, and 32 HS were recruited for participation. T-2 weighted magnetic resonance imaging scans were obtained on all subjects, and the total volume of all WMH for each subject was measured in cubic centimeters. The significance of difference between groups was tested using ANOVA with post-hoc adjustment for multiple comparisons. Further, we used logistic regression to test for trends between symptom load and total WMH volume.

RESULTS

The mean total volume of WMH in BP-I patients with psychotic features was significantly higher (p < 0.05) than that of HS. Further, we observed a positive linear trend by familiality and type of affectedness when comparing mean total WMH volume of HS, unaffected family members, subjects with BP-II, and BP-I with and without a history of psychosis (p < 0.05).

CONCLUSIONS

Based on a quantitative technique, WMH burden appears to be associated with familiality and type of BP. The significance of these findings remains to be fully elucidated.

Correlates of treatment response in depressed older adults with bipolar disorder

AIMS

To identify baseline clinical factors associated with acute treatment response in depressed older adults with bipolar disorder (BD) receiving lamotrigine.

METHODS

Secondary analysis of a multisite, 12-week, open-label, uncontrolled study of add-on lamotrigine in 57 adults 60 years and older with BD I or II depression. Measures included the Montgomery Asberg Depression Rating Scale (MADRS) and Young Mania Rating Scale (YMRS). Cardiometabolic risk was measured with total serum cholesterol and the Cumulative Illness Rating Scale-Geriatric (CIRS-G) item #13 (endocrine/metabolic burden). Neurocognitive (executive) function was evaluated using the Trail Making Test.

RESULTS

Greater reduction in MADRS from baseline was associated with higher baseline cardiometabolic burden at 6 and 9 weeks and lower YMRS scores at 9 weeks. At 12 weeks, improvement in the MADRS from baseline was no longer significantly related to baseline cardiometabolic burden or YMRS scores. A longitudinal mixed model of MADRS scores corroborated these findings with a significant finding of time-by-baseline cholesterol level interaction. In a subset of participants, better baseline executive function was related to greater improvement in the MADRS at 9 weeks but not at 6 or 12 weeks. Among all participants, higher baseline YMRS scores were related to greater likelihood of dropout.

CONCLUSIONS

Lamotrigine appears to work best in depressed elderly patients with BD who have high cardiometabolic risk and low level of mania. Agents like lamotrigine that act primarily on neuroprogressive pathways involving oxidative stress, neurotrophins, and inflammation may be particularly effective in individuals with BD who have significant cardiometabolic burden because of their effects on shared vulnerability factors in BD and medical illness.

Mitochondrial detachment of hexokinase 1 in mood and psychotic disorders: implications for brain energy metabolism and neurotrophic signaling

The pathophysiology of mood and psychotic disorders, including unipolar depression (UPD), bipolar disorder (BPD) and schizophrenia (SCHZ), is largely unknown. Numerous studies, from molecular to neuroimaging, indicate that some individuals with these disorders have impaired brain energy metabolism evidenced by abnormal glucose metabolism and mitochondrial dysfunction. However, underlying mechanisms are unclear. A critical feature of brain energy metabolism is attachment to the outer mitochondrial membrane (OMM) of hexokinase 1 (HK1), an initial and rate-limiting enzyme of glycolysis. HK1 attachment to the OMM greatly enhances HK1 enzyme activity and couples cytosolic glycolysis to mitochondrial oxidative phosphorylation, through which the cell produces most of its adenosine triphosphate (ATP). HK1 mitochondrial attachment is also important to the survival of neurons and other cells through prevention of apoptosis and oxidative damage. Here we show, for the first time, a decrease in HK1 attachment to the OMM in postmortem parietal cortex brain tissue of individuals with UPD, BPD and SCHZ compared to tissue from controls without psychiatric illness. Furthermore, we show that HK1 mitochondrial detachment is associated with increased activity of the polyol pathway, an alternative, anaerobic pathway of glucose metabolism. These findings were observed in samples from both medicated and medication-free individuals. We propose that HK1 mitochondrial detachment could be linked to these disorders through impaired energy metabolism, increased vulnerability to oxidative stress, and impaired brain growth and development.

The impact of general intellectual ability and white matter volume on the functional outcome of patients with Bipolar Disorder and their relatives

BACKGROUND

There is substantial evidence that cognitive deficits and brain structural abnormalities are present in patients with Bipolar Disorder (BD) and in their first-degree relatives. Previous studies have demonstrated associations between cognition and functional outcome in BD patients but have not examined the role of brain morphological changes. Similarly, the functional impact of either cognition or brain morphology in relatives remains unknown. Therefore we focused on delineating the relationship between psychosocial functioning, cognition and brain structure, in relation to disease expression and genetic risk for BD.

METHODS

Clinical, cognitive and brain structural measures were obtained from 41 euthymic BD patients and 50 of their unaffected first-degree relatives. Psychosocial function was evaluated using the General Assessment of Functioning (GAF) scale. We examined the relationship between level of functioning and general intellectual ability (IQ), memory, attention, executive functioning, symptomatology, illness course and total gray matter, white matter and cerebrospinal fluid volumes.

LIMITATIONS

Cross-sectional design.

RESULTS

Multiple regression analyses revealed that IQ, total white matter volume and a predominantly depressive illness course were independently associated with functional outcome in BD patients, but not in their relatives, and accounted for a substantial proportion (53%) of the variance in patients' GAF scores. There were no significant domain-specific associations between cognition and outcome after consideration of IQ.

CONCLUSIONS

Our results emphasise the role of IQ and white matter integrity in relation to outcome in BD and carry significant implications for treatment interventions.

Neurocognitive and neuroimaging predictors of clinical outcome in bipolar disorder

Historically, bipolar disorder has been conceptualized as a disease involving episodic rather than chronic dysfunction. However, increasing evidence indicates that bipolar disorder is associated with substantial inter-episode psychosocial and vocational impairment. Here we review the contributions of neurocognitive deficits and structural and functional neuroanatomic alterations to the observed functional impairments. In particular, compelling evidence now suggests that neurocognitive impairments, particularly in the areas of attention, processing speed, and memory, are associated with functional outcome. Although investigation of the neural correlates of functional disability in bipolar disorder is only in its nascent stages, preliminary evidence suggests that white matter abnormalities may be predictive of poor outcome. A better understanding of the relationship between neurocognitive and neuroimaging assays and functional outcome has the potential to improve current treatment options and provide targets for new treatment strategies in bipolar disorder.

Vascular diseases and old age mental disorders: an update of neuroimaging findings

PURPOSE OF REVIEW

To review neuroimaging findings that have been reported in samples of patients with cardiovascular disorders and their association with the onset of Alzheimer's disease, vascular dementia, depression and bipolar disorder in the elderly and to highlight the implications of these findings to the knowledge about the pathophysiology of psychiatric disorders in old age, as well as their potential clinical implications.

RECENT FINDINGS

Vascular risk factors, such as hypertension, diabetes, dyslipidemia, smoking habits and heart failure, have all been associated with signs of cerebrovascular dysfunction, including structural MRI findings of signal hyperintensities, lacunes and stroke and functional imaging findings of brain regional hypoperfusion and hypometabolism. Such brain abnormalities have been found to increase the risk of onset of psychiatric disorder (depression, bipolar and dementia) in old age.

SUMMARY

As vascular risk factors are potentially modifiable when detected in midlife, the early characterization of brain changes associated with the presence of cardiovascular diseases holds promise to afford clinical applications in psychiatry, providing new perspectives for the prevention of old age psychiatric disorders.

White matter lesions in euthymic patients with bipolar disorder

OBJECTIVE

We aimed to quantify both load and regional distributions of hyperintensities on magnetic resonance imaging (MRI) in prospectively verified euthymic bipolar patients and matched controls.

METHOD

Cerebral hyperintensities on T2, proton density and fluid-attenuated inversion recovery (FLAIR) MRI were compared between 48 bipolar and 47 control subjects using semi-quantitative rating scales.

RESULTS

Bipolar subjects had more severe frontal deep white matter lesions (DWML). Hyperintensity load was independent of age in bipolar patients but increased with age in controls. Global prevalence and severity of hyperintensities did not differ between groups. Exploratory analysis showed DWML in excess in the left hemisphere in bipolar subjects but not in controls.

CONCLUSION

Findings are consistent with clinical, particularly some neurocognitive, features of bipolar disorder and implicate fronto-subcortical circuits in its neurobiology. They more probably reflect a trait abnormality or illness scar rather than a mood state-dependent finding. Processes other than ageing and vascular factors may underlie their development.

A role for white matter abnormalities in the pathophysiology of bipolar disorder

Bipolar disorder is a chronically disabling psychiatric disorder characterized by manic states that is often interspersed with periods of depression whose neurobiology remains largely unknown. There is, however, increasing evidence that white matter (WM) abnormalities may play an important role in the neurobiology of the disorder. In this review we critically evaluate evidence for WM abnormalities in bipolar disorder obtained from neuroimaging, neuropathological, and genetic research. Increased rates of white matter hyperintensities, regional volumetric abnormalities, abnormal water diffusion along prefrontal-subcortical tracts, fewer oligodendrocytes in prefrontal WM, and alterations in the expression of myelin- and oligodendrocyte-related genes are among the most consistent findings. Abnormalities converge in the prefrontal WM and, in particular, tracts that connect prefrontal regions and subcortical gray matter structures known to be involved in emotion. Taken together, the evidence supports and clarifies a model of BD that involves disconnectivity in regions implicated in emotion generation and regulation.