The use of component-wise gradient boosting to assess the possible role of cognitive measures as markers of vulnerability to pediatric bipolar disorder.

BACKGROUND AND AIMS: Cognitive impairments are primary hallmarks symptoms of bipolar disorder (BD). Whether these deficits are markers of vulnerability or symptoms of the disease is still unclear. This study used a component-wise gradient (CGB) machine learning algorithm to identify cognitive measures that could accurately differentiate pediatric BD, unaffected offspring of BD parents, and healthy controls. METHODS: 59 healthy controls (HC; 11.19 ± 3.15 yo; 30 girls), 119 children and adolescents with BD (13.31 ± 3.02 yo, 52 girls) and 49 unaffected offspring of BD parents (UO; 9.36 ± 3.18 yo; 22 girls) completed the CANTAB cognitive battery. RESULTS: CGB achieved accuracy of 73.2% and an AUROC of 0.785 in classifying individuals as either BD or non-BD on a dataset held out for validation for testing. The strongest cognitive predictors of BD were measures of processing speed and affective processing. Measures of cognition did not differentiate between UO and HC. CONCLUSIONS: Alterations in processing speed and affective processing are markers of BD in pediatric populations. Longitudinal studies should determine whether UO with a cognitive profile similar to that of HC are at less or equal risk for mood disorders. Future studies should include relevant measures for BD such as verbal memory and genetic risk scores.

Are self-rated and behavioural measures of impulsivity in bipolar disorder mainly related to comorbid substance use problems?

INTRODUCTION: Impulsivity is a multidimensional feature observed in bipolar disorder (BD) and substance use disorder (SUD). We previously found a relationship between SUD and risk taking in BD. It is still unclear whether self-rated and behavioral impulsivity measures differ between BD with and without comorbid SUD, or are specific to BD. METHODS: 93 adults with BD with comorbid SUD, 91 BD without SUD, and 93 healthy controls (HC) were administered the Barratt Impulsivity Scale (BIS), the Behavioral Inhibition/Behavioral Activation System Scale (BIS/BAS), and the Cambridge Neuropsychological Test Automated Battery. Analyses compared impulsivity measures across groups controlling for age. Discriminant function analyses (DFA) assessed the combination of variables effectively predicting group membership. RESULTS: BD displayed increased BIS, BIS/BAS scores, reduced performance on the Cambridge Gambling and Rapid Visual Processing, and Affective Go/No-Go tasks compared to HC. Comparisons between BD with and without SUD showed increased BIS Motor impulsiveness. The overall predictive power of DFA was weak. CONCLUSIONS: Some facets of impulsivity are a core trait of BD and are partially independent from the presence of SUD. Motor impulsiveness may be distinctive of BD+SUD. More research is needed to understand the role of impulsive behaviors as risk factors for relapse in SUD.

Prediction of pediatric bipolar disorder using neuroanatomical signatures of the amygdala.

OBJECTIVES: Pediatric bipolar disorder is currently diagnosed based on signs and symptoms, and without objective diagnostic biomarkers. In the present study, we investigated the utility of structural neuroanatomical signatures of the amygdala to objectively differentiate individual subjects with pediatric bipolar disorder from matched healthy controls. METHODS: Structural T1 -weighted neuroimaging scans were obtained from 16 children and adolescents with unmedicated DSM-IV bipolar disorder (11 males, five females) and 16 matched healthy controls (11 males, five females). Voxel-based gray matter morphometric features extracted from a bilateral region-of-interest within the amygdala were used to develop a multivariate pattern analysis model which was utilized in predicting novel or 'unseen' individual subjects as either bipolar disorder or healthy controls. RESULTS: The model assigned 25 out of 32 subjects the correct label (bipolar disorder/healthy) translating to a 78.12% diagnostic accuracy, 81.25% sensitivity, 75.00% specificity, 76.47% positive predictive value, and 80.00% negative predictive value and an area under the receiver operating characteristic curve (ROC) of 0.81. The predictions were significant at p = 0.0014 (χ(2) test p-value). CONCLUSIONS: These results reaffirm previous reports on the existence of neuroanatomical abnormalities in the amygdala of pediatric patients with bipolar disorder. Remarkably, the present study also demonstrates that neuroanatomical signatures of the amygdala can predict individual subjects with bipolar disorder with a relatively high specificity and sensitivity. To the best of our knowledge, this is the first study to present a proof-of-concept diagnostic marker of pediatric bipolar disorder based on structural neuroimaging scans of largely medication-naïve patients.

Correlates of childhood trauma in children and adolescents with bipolar disorder spectrum: A preliminary study.

OBJECTIVE: Histories of childhood trauma (CT) are risk factors for affect dysregulation and poor clinical outcomes in women with bipolar disorder (BD). While much is known about the link between BD and CT in adult patients, there is limited data on this research topic in pediatric BD (PBD). The present study aims to investigate the impact of CT on irritability, aggressive and suicidal behaviors in PBD patients across gender types. METHODS: From 2013 to 2015, 59 PBD patients Aged 6-17 (30 female) were administered the Childhood Trauma Questionnaire (CTQ) along with scales assessing irritability (Affective Reactivity Index), aggression (Modified Overt Aggression Scale) and suicidal thoughts and behaviors (Columbia-Suicide Severity Rating Scale). We examined the severity of these behaviors across types of CT and gender using univariate regression analyses. Findings were adjusted for age, number of traumas, and CTQ denial score. RESULTS: In PBD patients, analyses showed that the effect of physical abuse depended on gender, whereby females were more likely than males to engage in suicidal thoughts and behaviors (p < 0.05). Male gender and CT were strong determinants of irritability (p < 0.05). Violence against property and people was found to be reduced in females, and increased in males with a history of emotional and sexual abuse, respectively (p < 0.05). CONCLUSION: These preliminary findings highlight the significant impact of CT in PBD and suggest that gender may predict the risk for dysfunctional behaviors in PBD patients with CT. Future large scale, longitudinal, investigations focusing on fear processing and extinction may provide a deeper understanding of these gender differences, and their role in the course of BD.

Increased reward-oriented impulsivity in older bipolar patients: A preliminary study.

OBJECTIVE: Impulsivity is a well-established trait of bipolar disorder (BD) that persists across mood phases. It is, however, still unknown whether, in BD, impulsivity remains stable or varies in intensity over the lifespan. This cross-sectional study compared impulsive behavior in older euthymic BD patients and healthy individuals using a range of self-rating and behavioral measures of impulsivity. METHODS: 28 BD patients (56.07 ± 4.08 years, 16 women) and 15 healthy controls (HC; 55.1 ± 3.95 years, 6 women) were administered the Barratt Impulsivity Scale (BIS) and selected tasks of the Cambridge Neuropsychological Test Automated Batter (CANTAB) reflecting impulsivity. Multivariate analysis of variance controlled for age compared impulsivity measures across BD and HC. RESULTS: BD patients displayed poor decision making, risk taking, and increased delay aversion. Other measures of impulsivity such as response inhibition, sustained cognitive control, and BIS scores were, overall, comparable between BD and HC. CONCLUSIONS: These preliminary findings suggest that, in BD, aspects of impulsivity related to reward-based decision making persist into late adulthood. Large scale, longitudinal studies are needed to evaluate the relationship of age to impulsivity over time, and explore the link between impulsivity and illness progression in elderly individuals with BD.

Effects of valproate on brain volumes in pediatric bipolar disorder: A preliminary study.

Sodium valproate (VPA) has well-established neuroprotective effects and is recommended as treatment in bipolar disorder patients. The neural effects of VPA in pediatric bipolar disorder (PBD) have yet to be established. This preliminary study explored the effects of VPA on brain structure in PBD. Fourteen PBD patients (10 males; mean = 13.43 ± 3.05 years old) underwent a structural MRI before and after a 6-week VPA treatment period. Bayesian linear mixed modeling explored seven brain region volumes as a function of dichotomous pre/post time. Results showed a decrease in amygdala volume over time. These findings need to be confirmed by large-scale, longitudinal studies.

The role of white matter in personality traits and affective processing in bipolar disorder.

BACKGROUND: Bipolar disorder (BD) is characterized by affective processing bias and variations in personality traits. It is still unknown whether these features are linked to the same structural brain alterations. The aim of this study was to investigate relationships between specific personality traits, white matter (WM) properties, and affective processing in BD and HC. METHODS: 24 healthy controls (HC) and 38 adults with BDI (HC: 29.47 ± 2.23 years, 15 females; BDI: 32.44 ± 1.84 years, 20 females) completed clinical scales and the Big Five Inventory. They were also administered the Affective Go/No-Go (AGN) and the Rapid Visual Processing (RVP) tasks of the Cambridge Neuropsychological Test Automated Battery. Diffusion Tensor Imaging (DTI) assessed the microstructure of WM tracts. RESULTS: In BDI measures of WM properties were reduced across all major brain white matter tracts. As expected, individuals with BDI reported greater neuroticism, lower agreeableness and conscientiousness, and made a greater number of errors in response to affective stimuli in the AGN task compared to HC. High neuroticism scores were associated with faster AGN latency, and overall reduced AGN accuracy in both HC and BDI. Elevated FA values were associated with reduced neuroticism and increased cognitive processing in HC but not in BDI. CONCLUSIONS: Our findings showed important potential links between personality, affective processing and WM integrity in BD. In the future therapeutic interventions for BD using brain stimulation protocols might benefit from the use of DTI to target pathways underlying abnormal affective processing.

Deep brain stimulation of the medial forebrain bundle: Distinctive responses in resistant depression.

BACKGROUND: Treatment resistant depression (TRD) is a serious, disabling disease. Deep brain stimulation (DBS) to the superolateral branch of the medial forebrain bundle (MFB), as proposed by Schlaepfer et al. (2013), has led to rapid anti-depressant response but has not been replicated. METHODS: In this interim analysis of an ongoing pilot study of ten subjects, we assessed the efficacy of MFB-DBS in a cohort of four TRD patients over a 52-week period using the Montgomery-Åsberg Depression Rating Scale (MADRS) as the primary assessment tool. Implanted patients entered a 4-week single-blinded sham stimulation period prior to stimulation initiation. Deterministic fiber tracking analysis was performed to compare modulated fiber tracts between patients. RESULTS: Intraoperatively, responder patients displayed immediate increased signs of energy and motivation upon stimulation at target. There was no significant mean change in mood during sham stimulation phase. Three of 4 patients had >50% decrease in MADRS scores at 7 days post-stimulation initiation relative to baseline. One patient withdrew from study participation. At 26 weeks, two of 3 remaining patients continue to have >80% decrease in MADRS scores. One patient failed to have response; evaluation of modulated fiber tracts revealed reduced frontal connectivity to the target region. LIMITATIONS: This is an interim report, with limited conclusions. CONCLUSION: This study of MFB-DBS shows similar rapid anti-depressant effects within the first week of stimulation as initially reported by Schlaepfer et al. (2013). Implementation of anhedonia measurements would greatly augment characterization of the striking motivational effects observed. We urge others to pursue this target to further prove efficacy. ClinicalTrials.gov (identifier: NCT02046330) https://clinicaltrials.gov/ct2/show/NCT02046330.

Neurocognitive functioning in individuals with bipolar disorder and their healthy siblings: A preliminary study.

BACKGROUND: Cognitive deficits have been consistently reported in individuals with bipolar disorder (BD). The cognitive profile of siblings of individuals with BD is, however, less clearly established possibly due to the heterogeneity of neuropsychological measures used in previous studies. The aim of this exploratory study was to assess the cognitive function of siblings of individuals with BD and compare it with that of their first-degree relatives suffering with BD, and healthy controls (HC) using the Cambridge Neuropsychological Test Automated Battery (CANTAB) - a comprehensive and validated computerized cognitive battery. METHODS: We recruited 23 HC (33.52±10.29 years, 8 males), 27 individuals with BD (34.26±10.19 years, 9 males, 25 BDI, 1BDII and 1 BD-NOS), and 15 of their biologically related siblings (37.47±13.15 years, 4 males). Siblings had no current or lifetime history of mental disorders. Participants performed the CANTAB and completed questionnaires assessing mood and global functioning. Multivariate analyses compared CANTAB measures across the three participant groups. RESULTS: Individuals with BD and their siblings were less accurate in a task of sustained attention (Rapid Visual Processing) when compared to HC. Further, individuals with BD displayed pronounced deficits in affective processing (Affective Go/No-Go) compared to HC. There were no cognitive differences between siblings and individuals with BD. After correcting for current depressive symptoms, these results did not reach statistical significance. CONCLUSIONS: Subthreshold depressive symptoms may be associated with reduced sustained attention in healthy siblings of BD patients. This preliminary result needs to be corroborated by large-scale, longitudinal studies assessing the relationship between cognition and mood in vulnerable individuals.