Pablo Najt | University of Galway (original) (raw)

Papers by Pablo Najt

Research paper thumbnail of Anatomical measurements of the orbitofrontal cortex in child and adolescent patients with bipolar disorder

Imaging studies indicate smaller orbitofrontal cortex (OFC) volume in mood disorder patients comp... more Imaging studies indicate smaller orbitofrontal cortex (OFC) volume in mood disorder patients compared with healthy subjects. We sought to determine whether child and adolescent patients with bipolar disorder have smaller OFC volumes than healthy controls. Fourteen children and adolescents meeting DSM-IV criteria for bipolar disorder (six males and eight females with a mean age ± S.D. = 15.5 ± 3.2 years) and 20 healthy controls (11 males and nine females with mean age ± S.D. = 16.9 ± 3.8 years) were studied. Orbitofrontal cortex volume was measured using magnetic resonance imaging. Male bipolar patients had smaller gray matter volumes in medial (p = 0.044), right medial (0.037) and right (p = 0.032) lateral OFC subdivisions compared to male controls. In contrast, female patients had larger gray matter volumes in left (p = 0.03), lateral (p = 0.012), left lateral (p = 0.007), and trends for larger volumes in right lateral and left medial OFC subdivisions compared with female controls. Male patients exhibit smaller gray matter volumes, while female patients exhibit larger volumes in some OFC sub-regions. Gender differences in OFC abnormalities may be involved in illness pathophysiology among young bipolar patients.

Research paper thumbnail of Anterior Cortical Development During Adolescence in Bipolar Disorder

Biological Psychiatry, 2015

Increasing evidence supports a neurodevelopmental model for bipolar disorder (BD), with adolescen... more Increasing evidence supports a neurodevelopmental model for bipolar disorder (BD), with adolescence as a critical period in its development. Developmental abnormalities of anterior paralimbic and heteromodal frontal cortices, key structures in emotional regulation processes and central in BD, are implicated. However, few longitudinal studies have been conducted, limiting understanding of trajectory alterations in BD. In this study, we performed longitudinal neuroimaging of adolescents with and without BD and assessed volume changes over time, including changes in tissue overall and within gray and white matter. Larger decreases over time in anterior cortical volumes in the adolescents with BD were hypothesized. Gray matter decreases and white matter increases are typically observed during adolescence in anterior cortices. It was hypothesized that volume decreases over time in BD would reflect alterations in those processes, showing larger gray matter contraction and decreased white matter expansion. Two high-resolution magnetic resonance imaging scans were obtained approximately 2 years apart for 35 adolescents with bipolar I disorder (BDI) and 37 healthy adolescents. Differences over time between groups were investigated for volume overall and specifically for gray and white matter. Relative to healthy adolescents, adolescents with BDI showed greater volume contraction over time in a region including insula and orbitofrontal, rostral, and dorsolateral prefrontal cortices (p < .05, corrected), including greater gray matter contraction and decreased white matter expansion over time, in the BD compared with the healthy group. The findings support neurodevelopmental abnormalities during adolescence in BDI in anterior cortices, including altered developmental trajectories of anterior gray and white matter.

Research paper thumbnail of Atypical right hemispheric functioning in the euthymic state of bipolar affective disorder

Psychiatry research, Jan 15, 2014

Bipolar disorder (BD) has been associated with right hemisphere dysfunction. These findings usual... more Bipolar disorder (BD) has been associated with right hemisphere dysfunction. These findings usually come from studies that have not distinguished between symptomatic and euthymic states of BD. The present study aims to investigate atypical right (and left) hemispheric functioning in euthymic BD patients. We evaluated 40 participants (18 healthy controls and 22 euthymic BD patients) using an emotional prosody dichotic listening task and a linguistic dichotic listening task which have been shown to produce a strong left ear advantage (LEA) and right ear advantage (REA), indicating a right and left hemisphere superiority, respectively. The results replicate the well-known LEA in emotional prosody for healthy controls. In contrast, no ear advantage was found for emotional prosody in euthymic BD patients. Both groups revealed the well-established REA in the linguistic dichotic listening task. The patient group was heterogeneous with regard to medication, as it consisted of patients with ...

Research paper thumbnail of Right fronto-parietal dysfunction underlying spatial attention in bipolar disorder

Psychiatry Research, 2013

Although the neural underpinning of bipolar disorder (BD) is still unknown, recent research sugge... more Although the neural underpinning of bipolar disorder (BD) is still unknown, recent research suggests that the right fronto-parietal cortex is particularly affected in BD patients. If this were true, we would expect atypical functional cerebral asymmetries in allocation of visuospatial attention. To test this hypothesis, euthymic BD patients and age- and gender-matched healthy controls were compared on the visual line-bisection task, a reliable measure of visuospatial attention, associated with right parietal function. Line bisection performance (i.e. absolute and directional bias) was compared between groups as a function of response hand and line position. The results showed a typical hand-use effect in healthy controls involving a larger leftward bias (i.e. pseudoneglect) with the left hand than with the right hand. Although euthymic BD patients did not differ from healthy controls in the overall accuracy (i.e. absolute bias), they differed significantly in the directional line bisection bias. In contrast to healthy controls, BD patients did not significantly deviate from the veridical center, regardless of which hand was used to bisect horizontal lines. This finding indicates an atypical functional cerebral asymmetry in visuospatial attention in euthymic BD patients, supporting the idea of a dysfunction especially in the right fronto-parietal cortex.

Research paper thumbnail of Anatomical measurements of the orbitofrontal cortex in child and adolescent patients with bipolar disorder

Neuroscience Letters, 2007

Research paper thumbnail of Attention deficits in bipolar disorder: a comparison based on the Continuous Performance Test

Neuroscience Letters, 2005

Although attentional deficits measured by Continuous Performance Tests (CPTs) have been observed ... more Although attentional deficits measured by Continuous Performance Tests (CPTs) have been observed in patients with bipolar disorder, their relationship with clinical state is not well understood. The identical pairs Continuous Performance Test (CPT-IP) shows particular promise as a measure sensitive to trait abnormalities in attentional function. In this study, the CPT-IP was administered to 27 patients with bipolar disorder (22 type I, 5 type II) and 25 demographically matched healthy comparison subjects, in order to assess the presence and nature of attentional deficits as a function of mood symptoms. Results showed significantly impaired CPT performance in bipolar patients compared with healthy subjects. Patients made fewer hits (p < 0.01), were slower to respond (p < 0.007), and had poorer discrimination (p < 0.05) and bias (p < 0.006) than comparison subjects. Severity of mania and depression was not correlated with any of the CPT measures. Our findings suggest that attentional dysfunction may be a trait deficit associated with bipolar illness. However, within-subjects longitudinal studies examining fluctuations in performance over time are needed.

Research paper thumbnail of Prefrontal hyperactivation during working memory task in untreated individuals with major depressive disorder

Molecular Psychiatry, 2007

The prefrontal cortex, a part of the limbic-thalamic-cortical network, participates in regulation... more The prefrontal cortex, a part of the limbic-thalamic-cortical network, participates in regulation of mood, cognition and behavior and has been implicated in the pathophysiology of major depressive disorder (MDD). Many neuropsychological studies demonstrate impairment of working memory in patients with MDD. However, there are few functional neuroimaging studies of MDD patients during working memory processing, and most of the available ones included medicated patients or patients with both MDD and bipolar disorder. We used functional magnetic resonance imaging (fMRI) to measure prefrontal cortex function during working memory processing in untreated depressed patients with MDD. Fifteen untreated individuals with Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition recurrent MDD (mean age7s.d. = 34.3711.5 years) and 15 healthy comparison subjects (37.7712.1 years) matched for age, sex and race were studied using a GE/Elscint 2T MR system. An echo-planar MRI sequence was used to acquire 24 axial slices. The n-back task (0-back, 1-back and 2-back) was used to elicit frontal cortex activation. Data were analyzed with a multiple regression analysis using the FSL-FEAT software. MDD patients showed significantly greater left dorsolateral cortex activation during the n-back task compared to the healthy controls (P < 0.01), although task performance was similar in the two groups. Furthermore, the patients showed significant anterior cingulate cortex activation during the task, but the comparison subjects did not (P < 0.01). This study provides in vivo imaging evidence of abnormal frontolimbic circuit function during working memory processing in individuals with MDD.

Research paper thumbnail of Trait impulsivity in patients with mood disorders

Journal of Affective Disorders, 2007

Background: Impulsivity is a key component of the manic behavior of bipolar disorder and is repor... more Background: Impulsivity is a key component of the manic behavior of bipolar disorder and is reported to occur in bipolar patients as a stable characteristic, i.e. a trait. Nevertheless, impulsivity has not been widely studied in depressed bipolar patients. We assessed impulsivity in depressed and euthymic bipolar and unipolar patients and healthy controls. We hypothesized that bipolar subjects would have higher levels of trait impulsivity than the comparison groups. Methods: Twenty-four depressed bipolar, 24 depressed unipolar, 12 euthymic bipolar, and 10 euthymic unipolar patients, as well as 51 healthy subjects were evaluated with the Barratt Impulsiveness Scale (BIS). Analysis of covariance with age and sex as covariates was used to compare mean group differences. Results: Depressed bipolar, euthymic bipolar, and depressed unipolar patients did not differ, and showed greater impulsivity than healthy controls on all of the BIS scales. Euthymic unipolar patients scored higher than healthy controls only on motor impulsivity. Limitations: Higher number of past substance abusers in the bipolar groups, and no control for anxiety and personality disorders, as well as small sample sizes, limit the reach of this study. Conclusions: This study replicates prior findings of stable trait impulsivity in bipolar disorder patients, and extends them, confirming that this trait can be demonstrated in depressed patients, as well as manic and euthymic ones. Trait impulsivity may be the result of repeated mood episodes or be present prior to their onset, either way it would influence the clinical presentation of bipolar disorder.

Research paper thumbnail of Oral Platform PresentationsAtypical functional cerebral asymmetries in men with schizotypy

International Clinical Psychopharmacology, 2011

Research paper thumbnail of Abnormal Cortical Morphology in Offenders with Psychopathy

Research paper thumbnail of Cortex and amygdala morphology in psychopathy

Psychiatry Research: Neuroimaging, 2011

Psychopathy is characterized by abnormal emotional processes, but only recent neuroimaging studie... more Psychopathy is characterized by abnormal emotional processes, but only recent neuroimaging studies have investigated its cerebral correlates. The study aim was to map local differences of cortical and amygdalar morphology. Cortical pattern matching and radial distance mapping techniques were used to analyze the magnetic resonance images of 26 violent male offenders (age: 32±8) with psychopathy diagnosed using the Psychopathy Checklist-Revised (PCL-R) and no schizophrenia spectrum disorders, and in matched controls (age: 35± sp=&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;0.12&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;/&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;11). The cortex displayed up to 20% reduction in the orbitofrontal and midline structures (corrected p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001 bilaterally). Up to 30% tissue reduction in the basolateral nucleus, and 10-30% enlargement effects in the central and lateral nuclei indicated abnormal structure of the amygdala (corrected p=0.05 on the right; and symmetrical pattern on the left). Psychopathy features specific morphology of the main cerebral structures involved in cognitive and emotional processing, consistent with clinical and functional data, and with a hypothesis of an alternative evolutionary brain development.

Research paper thumbnail of Impulsivity and bipolar disorder.

Research paper thumbnail of Co-occurring mental and substance abuse disorders: a review on the potential predictors and clinical outcomes.

Research paper thumbnail of Abnormal resting state corticolimbic blood flow in depressed unmedicated patients with major depression: a (15)O-H(2)O PET study.

Research paper thumbnail of Cortex and amygdala morphology in psychopathy.

Research paper thumbnail of Models of hemispheric specialization in facial emotion perception-a reevaluation.

Research paper thumbnail of Atypical lateralisation in emotional prosody in men with schizotypy.

Research paper thumbnail of Amygdala Hyperactivation In Untreated Depressed Individuals

Psychiatry Research: …, Jan 1, 2009

Research paper thumbnail of Association of Psychosis With Suicidality In Pediatric Bipolar I, II and Bipolar NOS Patients

Journal of affective …, Jan 1, 2006

Research paper thumbnail of Temperament and Character Traits In Major Depressive Disorder: Influence of Mood State and Recurrence of Episodes

Depression and …, Jan 1, 2009

The objective of this study was to compare personality traits between major depressive disorder (... more The objective of this study was to compare personality traits between major depressive disorder (MDD) patients and healthy comparison subjects (HC) and examine if personality traits in patients are associated with specific clinical characteristics of the disorder. Sixty MDD patients (45 depressed, 15 remitted) were compared to 60 HC using the Temperament and Character Inventory. Analysis of covariance, with age and gender as covariates, was used to compare the mean Temperament and Character Inventory scores among the subject groups. Depressed MDD patients scored significantly higher than HC on novelty seeking, harm avoidance, and self-transcendence and lower on reward dependence, self-directedness, and cooperativeness. Remitted MDD patients scored significantly lower than HC only on self-directedness. Comorbidity with anxiety disorder had a main effect only on harm avoidance. Harm avoidance was positively correlated with depression intensity and with number of episodes. Self-directedness had an inverse correlation with depression intensity. MDD patients present a different personality profile from HC, and these differences are influenced by mood state and comorbid anxiety disorders. When considering patients who have been in remission for some time, the differences pertain to few personality dimensions. Cumulated number of depressive episodes may result in increased harm avoidance.

Research paper thumbnail of Anatomical measurements of the orbitofrontal cortex in child and adolescent patients with bipolar disorder

Imaging studies indicate smaller orbitofrontal cortex (OFC) volume in mood disorder patients comp... more Imaging studies indicate smaller orbitofrontal cortex (OFC) volume in mood disorder patients compared with healthy subjects. We sought to determine whether child and adolescent patients with bipolar disorder have smaller OFC volumes than healthy controls. Fourteen children and adolescents meeting DSM-IV criteria for bipolar disorder (six males and eight females with a mean age ± S.D. = 15.5 ± 3.2 years) and 20 healthy controls (11 males and nine females with mean age ± S.D. = 16.9 ± 3.8 years) were studied. Orbitofrontal cortex volume was measured using magnetic resonance imaging. Male bipolar patients had smaller gray matter volumes in medial (p = 0.044), right medial (0.037) and right (p = 0.032) lateral OFC subdivisions compared to male controls. In contrast, female patients had larger gray matter volumes in left (p = 0.03), lateral (p = 0.012), left lateral (p = 0.007), and trends for larger volumes in right lateral and left medial OFC subdivisions compared with female controls. Male patients exhibit smaller gray matter volumes, while female patients exhibit larger volumes in some OFC sub-regions. Gender differences in OFC abnormalities may be involved in illness pathophysiology among young bipolar patients.

Research paper thumbnail of Anterior Cortical Development During Adolescence in Bipolar Disorder

Biological Psychiatry, 2015

Increasing evidence supports a neurodevelopmental model for bipolar disorder (BD), with adolescen... more Increasing evidence supports a neurodevelopmental model for bipolar disorder (BD), with adolescence as a critical period in its development. Developmental abnormalities of anterior paralimbic and heteromodal frontal cortices, key structures in emotional regulation processes and central in BD, are implicated. However, few longitudinal studies have been conducted, limiting understanding of trajectory alterations in BD. In this study, we performed longitudinal neuroimaging of adolescents with and without BD and assessed volume changes over time, including changes in tissue overall and within gray and white matter. Larger decreases over time in anterior cortical volumes in the adolescents with BD were hypothesized. Gray matter decreases and white matter increases are typically observed during adolescence in anterior cortices. It was hypothesized that volume decreases over time in BD would reflect alterations in those processes, showing larger gray matter contraction and decreased white matter expansion. Two high-resolution magnetic resonance imaging scans were obtained approximately 2 years apart for 35 adolescents with bipolar I disorder (BDI) and 37 healthy adolescents. Differences over time between groups were investigated for volume overall and specifically for gray and white matter. Relative to healthy adolescents, adolescents with BDI showed greater volume contraction over time in a region including insula and orbitofrontal, rostral, and dorsolateral prefrontal cortices (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .05, corrected), including greater gray matter contraction and decreased white matter expansion over time, in the BD compared with the healthy group. The findings support neurodevelopmental abnormalities during adolescence in BDI in anterior cortices, including altered developmental trajectories of anterior gray and white matter.

Research paper thumbnail of Atypical right hemispheric functioning in the euthymic state of bipolar affective disorder

Psychiatry research, Jan 15, 2014

Bipolar disorder (BD) has been associated with right hemisphere dysfunction. These findings usual... more Bipolar disorder (BD) has been associated with right hemisphere dysfunction. These findings usually come from studies that have not distinguished between symptomatic and euthymic states of BD. The present study aims to investigate atypical right (and left) hemispheric functioning in euthymic BD patients. We evaluated 40 participants (18 healthy controls and 22 euthymic BD patients) using an emotional prosody dichotic listening task and a linguistic dichotic listening task which have been shown to produce a strong left ear advantage (LEA) and right ear advantage (REA), indicating a right and left hemisphere superiority, respectively. The results replicate the well-known LEA in emotional prosody for healthy controls. In contrast, no ear advantage was found for emotional prosody in euthymic BD patients. Both groups revealed the well-established REA in the linguistic dichotic listening task. The patient group was heterogeneous with regard to medication, as it consisted of patients with ...

Research paper thumbnail of Right fronto-parietal dysfunction underlying spatial attention in bipolar disorder

Psychiatry Research, 2013

Although the neural underpinning of bipolar disorder (BD) is still unknown, recent research sugge... more Although the neural underpinning of bipolar disorder (BD) is still unknown, recent research suggests that the right fronto-parietal cortex is particularly affected in BD patients. If this were true, we would expect atypical functional cerebral asymmetries in allocation of visuospatial attention. To test this hypothesis, euthymic BD patients and age- and gender-matched healthy controls were compared on the visual line-bisection task, a reliable measure of visuospatial attention, associated with right parietal function. Line bisection performance (i.e. absolute and directional bias) was compared between groups as a function of response hand and line position. The results showed a typical hand-use effect in healthy controls involving a larger leftward bias (i.e. pseudoneglect) with the left hand than with the right hand. Although euthymic BD patients did not differ from healthy controls in the overall accuracy (i.e. absolute bias), they differed significantly in the directional line bisection bias. In contrast to healthy controls, BD patients did not significantly deviate from the veridical center, regardless of which hand was used to bisect horizontal lines. This finding indicates an atypical functional cerebral asymmetry in visuospatial attention in euthymic BD patients, supporting the idea of a dysfunction especially in the right fronto-parietal cortex.

Research paper thumbnail of Anatomical measurements of the orbitofrontal cortex in child and adolescent patients with bipolar disorder

Neuroscience Letters, 2007

Research paper thumbnail of Attention deficits in bipolar disorder: a comparison based on the Continuous Performance Test

Neuroscience Letters, 2005

Although attentional deficits measured by Continuous Performance Tests (CPTs) have been observed ... more Although attentional deficits measured by Continuous Performance Tests (CPTs) have been observed in patients with bipolar disorder, their relationship with clinical state is not well understood. The identical pairs Continuous Performance Test (CPT-IP) shows particular promise as a measure sensitive to trait abnormalities in attentional function. In this study, the CPT-IP was administered to 27 patients with bipolar disorder (22 type I, 5 type II) and 25 demographically matched healthy comparison subjects, in order to assess the presence and nature of attentional deficits as a function of mood symptoms. Results showed significantly impaired CPT performance in bipolar patients compared with healthy subjects. Patients made fewer hits (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.01), were slower to respond (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.007), and had poorer discrimination (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05) and bias (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.006) than comparison subjects. Severity of mania and depression was not correlated with any of the CPT measures. Our findings suggest that attentional dysfunction may be a trait deficit associated with bipolar illness. However, within-subjects longitudinal studies examining fluctuations in performance over time are needed.

Research paper thumbnail of Prefrontal hyperactivation during working memory task in untreated individuals with major depressive disorder

Molecular Psychiatry, 2007

The prefrontal cortex, a part of the limbic-thalamic-cortical network, participates in regulation... more The prefrontal cortex, a part of the limbic-thalamic-cortical network, participates in regulation of mood, cognition and behavior and has been implicated in the pathophysiology of major depressive disorder (MDD). Many neuropsychological studies demonstrate impairment of working memory in patients with MDD. However, there are few functional neuroimaging studies of MDD patients during working memory processing, and most of the available ones included medicated patients or patients with both MDD and bipolar disorder. We used functional magnetic resonance imaging (fMRI) to measure prefrontal cortex function during working memory processing in untreated depressed patients with MDD. Fifteen untreated individuals with Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition recurrent MDD (mean age7s.d. = 34.3711.5 years) and 15 healthy comparison subjects (37.7712.1 years) matched for age, sex and race were studied using a GE/Elscint 2T MR system. An echo-planar MRI sequence was used to acquire 24 axial slices. The n-back task (0-back, 1-back and 2-back) was used to elicit frontal cortex activation. Data were analyzed with a multiple regression analysis using the FSL-FEAT software. MDD patients showed significantly greater left dorsolateral cortex activation during the n-back task compared to the healthy controls (P < 0.01), although task performance was similar in the two groups. Furthermore, the patients showed significant anterior cingulate cortex activation during the task, but the comparison subjects did not (P < 0.01). This study provides in vivo imaging evidence of abnormal frontolimbic circuit function during working memory processing in individuals with MDD.

Research paper thumbnail of Trait impulsivity in patients with mood disorders

Journal of Affective Disorders, 2007

Background: Impulsivity is a key component of the manic behavior of bipolar disorder and is repor... more Background: Impulsivity is a key component of the manic behavior of bipolar disorder and is reported to occur in bipolar patients as a stable characteristic, i.e. a trait. Nevertheless, impulsivity has not been widely studied in depressed bipolar patients. We assessed impulsivity in depressed and euthymic bipolar and unipolar patients and healthy controls. We hypothesized that bipolar subjects would have higher levels of trait impulsivity than the comparison groups. Methods: Twenty-four depressed bipolar, 24 depressed unipolar, 12 euthymic bipolar, and 10 euthymic unipolar patients, as well as 51 healthy subjects were evaluated with the Barratt Impulsiveness Scale (BIS). Analysis of covariance with age and sex as covariates was used to compare mean group differences. Results: Depressed bipolar, euthymic bipolar, and depressed unipolar patients did not differ, and showed greater impulsivity than healthy controls on all of the BIS scales. Euthymic unipolar patients scored higher than healthy controls only on motor impulsivity. Limitations: Higher number of past substance abusers in the bipolar groups, and no control for anxiety and personality disorders, as well as small sample sizes, limit the reach of this study. Conclusions: This study replicates prior findings of stable trait impulsivity in bipolar disorder patients, and extends them, confirming that this trait can be demonstrated in depressed patients, as well as manic and euthymic ones. Trait impulsivity may be the result of repeated mood episodes or be present prior to their onset, either way it would influence the clinical presentation of bipolar disorder.

Research paper thumbnail of Oral Platform PresentationsAtypical functional cerebral asymmetries in men with schizotypy

International Clinical Psychopharmacology, 2011

Research paper thumbnail of Abnormal Cortical Morphology in Offenders with Psychopathy

Research paper thumbnail of Cortex and amygdala morphology in psychopathy

Psychiatry Research: Neuroimaging, 2011

Psychopathy is characterized by abnormal emotional processes, but only recent neuroimaging studie... more Psychopathy is characterized by abnormal emotional processes, but only recent neuroimaging studies have investigated its cerebral correlates. The study aim was to map local differences of cortical and amygdalar morphology. Cortical pattern matching and radial distance mapping techniques were used to analyze the magnetic resonance images of 26 violent male offenders (age: 32±8) with psychopathy diagnosed using the Psychopathy Checklist-Revised (PCL-R) and no schizophrenia spectrum disorders, and in matched controls (age: 35± sp=&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;0.12&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;/&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;11). The cortex displayed up to 20% reduction in the orbitofrontal and midline structures (corrected p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001 bilaterally). Up to 30% tissue reduction in the basolateral nucleus, and 10-30% enlargement effects in the central and lateral nuclei indicated abnormal structure of the amygdala (corrected p=0.05 on the right; and symmetrical pattern on the left). Psychopathy features specific morphology of the main cerebral structures involved in cognitive and emotional processing, consistent with clinical and functional data, and with a hypothesis of an alternative evolutionary brain development.

Research paper thumbnail of Impulsivity and bipolar disorder.

Research paper thumbnail of Co-occurring mental and substance abuse disorders: a review on the potential predictors and clinical outcomes.

Research paper thumbnail of Abnormal resting state corticolimbic blood flow in depressed unmedicated patients with major depression: a (15)O-H(2)O PET study.

Research paper thumbnail of Cortex and amygdala morphology in psychopathy.

Research paper thumbnail of Models of hemispheric specialization in facial emotion perception-a reevaluation.

Research paper thumbnail of Atypical lateralisation in emotional prosody in men with schizotypy.

Research paper thumbnail of Amygdala Hyperactivation In Untreated Depressed Individuals

Psychiatry Research: …, Jan 1, 2009

Research paper thumbnail of Association of Psychosis With Suicidality In Pediatric Bipolar I, II and Bipolar NOS Patients

Journal of affective …, Jan 1, 2006

Research paper thumbnail of Temperament and Character Traits In Major Depressive Disorder: Influence of Mood State and Recurrence of Episodes

Depression and …, Jan 1, 2009

The objective of this study was to compare personality traits between major depressive disorder (... more The objective of this study was to compare personality traits between major depressive disorder (MDD) patients and healthy comparison subjects (HC) and examine if personality traits in patients are associated with specific clinical characteristics of the disorder. Sixty MDD patients (45 depressed, 15 remitted) were compared to 60 HC using the Temperament and Character Inventory. Analysis of covariance, with age and gender as covariates, was used to compare the mean Temperament and Character Inventory scores among the subject groups. Depressed MDD patients scored significantly higher than HC on novelty seeking, harm avoidance, and self-transcendence and lower on reward dependence, self-directedness, and cooperativeness. Remitted MDD patients scored significantly lower than HC only on self-directedness. Comorbidity with anxiety disorder had a main effect only on harm avoidance. Harm avoidance was positively correlated with depression intensity and with number of episodes. Self-directedness had an inverse correlation with depression intensity. MDD patients present a different personality profile from HC, and these differences are influenced by mood state and comorbid anxiety disorders. When considering patients who have been in remission for some time, the differences pertain to few personality dimensions. Cumulated number of depressive episodes may result in increased harm avoidance.