Age-related changes in the corpus callosum in early-onset bipolar disorder assessed using volumetric and cross-sectional measurements

Transient splenial lesion syndrome in bipolar-II disorder: a case report highlighting reversible brain changes during hypomanic episodes

Background

Reversible splenial lesion syndrome (RESLES) is a rare neurological condition characterized by temporary abnormalities in the splenium of the corpus callosum, which has been reported in mental disorders. Previous studies on bipolar disorder (BD) primarily focused on aspects such as brain structure and function, neurochemical changes, and genetics. However, there have been no studies reporting the occurrence of this syndrome during hypomanic episodes and its disappearance during the remission phase in bipolar disorder type 2 (BD-II).

Case presentation

We present a case report of a 30 years-old female patient with BD-II who exhibited symptoms of RESLES during a hypomanic episode. The patient, with a 12 years psychiatric history, has experienced recurrent depressive episodes initially, with the first hypomanic episode occurring 8 years ago. During this period, this patient made several visits to the outpatient clinic to have her medications adjusted due to repeated suicide attempts. This time, she was admitted to our hospital with a second hypomanic episode due to drug withdrawal during pregnancy. The RESLES was observed on her brain magnetic resonance image, and it was alleviated after treatment with lithium carbonate and quetiapine until achieving remission.

Conclusion

We present the first report of identifying RESLES in BD-II with hypomanic episodes, which subsequently disappears during the remission phase. Our case report highlights a potential association between BD and RESLES, emphasizing the need for future studies to explore the underlying mechanisms connecting these two conditions in greater depth.

Brain ageing and neurodegeneration in bipolar disorder

BACKGROUND

Bipolar disorder (BD) is a psychiatric condition characterized by alternating episodes of mania and depression frequently associated with cognitive impairments. BD is associated with brain alterations in fronto-temporal and limbic networks. Recent conceptualizations view BD as a neurodegenerative disorder characterized by progressive deterioration of grey and white matter (GM, WM) volumes and accelerated brain ageing. Therefore, we conducted a review gathering neuroimaging evidence about neurodegenerative processes in BD.

METHODS

A literature search was conducted on the PubMed, Scopus and Web of Science databases in September 2021. After title and abstract screening of the retrieved records, 19 studies that met our inclusion criteria were included in the review.

RESULTS

The available evidence suggests the presence of a progressive reduction of GM volumes at the whole-brain level and in the amygdala, prefrontal regions and the anterior cingulate cortex. Conversely, WM lesions and alterations seem to emerge only in the early phases of the condition masking the effects of normal ageing. Lastly, machine learning models indicate that the gap between predicted and chronological brain age differs considerably between healthy controls and BD patients, as the latter are characterized by larger gaps.

LIMITATIONS

The included studies had cross-sectional study design, small sample sizes and heterogeneous methodology, and lack of control for pharmacological treatment.

CONCLUSIONS

BD seems to be associated with generalized age-related structural GM volumes reductions and functional brain alterations thus suggesting the presence of neurodegenerative processes. Future systematic reviews and meta-analyses should be conducted to quantify the magnitude of brain ageing-related effects in BD.

Defining neuroplasticity

Neuroplasticity, i.e., the modifiability of the brain, is different in development and adulthood. The first includes changes in: (i) neurogenesis and control of neuron number; (ii) neuronal migration; (iii) differentiation of the somato-dendritic and axonal phenotypes; (iv) formation of connections; (v) cytoarchitectonic differentiation. These changes are often interrelated and can lead to: (vi) system-wide modifications of brain structure as well as to (vii) acquisition of specific functions such as ocular dominance or language. Myelination appears to be plastic both in development and adulthood, at least, in rodents. Adult neuroplasticity is limited, and is mainly expressed as changes in the strength of excitatory and inhibitory synapses while the attempts to regenerate connections have met with limited success. The outcomes of neuroplasticity are not necessarily adaptive, but can also be the cause of neurological and psychiatric pathologies.

Relationships between corpus callosum and language lateralization in patients with schizophrenia and bipolar disorders

OBJECTIVES

The question of whether there is a continuum or a dichotomy among patients with schizophrenia (SZ) and bipolar disorders (BD) has not been clearly resolved and remains a challenge. Thus, the identification of specific biomarkers of these disorders might be helpful. The present study investigated the volume of the corpus callosum (CC) and functional lateralization for language as potential biomarkers and their relationships in SZ and BD.

METHODS

The study included 20 patients with SZ, 20 patients with BD and 40 healthy controls (HC). A functional lateralization index (FLI) was computed for each participant within the language comprehension network. For each participant, the volume of the total CC and those of three subregions were extracted. These variables and their anatomo-functional relationships were investigated.

RESULTS

In comparison to HC, SZ patients presented a decreased leftward lateralization for language, whereas this was not found in BD patients. However, as compared to SZ patients and HC, BD patients showed a reduction in CC volume associated with a lower leftward lateralization for language.

CONCLUSIONS

Our study revealed that SZ patients displayed a reduction of the leftward functional lateralization for language; however, no reduction of CC volume was observed, whereas BD patients presented a decreased volume of the CC associated with a lower leftward asymmetry for language. The results of our study detected distinct anomalies in both SZ and BD that may be considered as specific biomarkers of these disorders related to neurodevelopmental models.

Corpus callosum volumes in bipolar disorders and suicidal vulnerability

Reduced size of the corpus callosum (CC) has been associated with bipolar disorders and suicidality. Here, we aimed at investigating the relative independence of these associations in a large sample of patients. Two samples of males and females totaling 209 euthymic participants were recruited, including 72 patients with a major depressive disorder, 64 with bipolar disorders and 73 healthy controls. Among patients, 61 had a lifetime history of suicide attempt and 75 had none. Structural scans were acquired with 1.5T magnetic resonance imaging. Surface-based morphometry (Freesurfer) analysis was used to compute the volumes of the CC. In the whole sample, there was a significant reduction in the volume of mid-anterior, central, and mid-posterior (all p<0.008) CC in bipolar patients independently from suicidality, with medium effect sizes between unipolar and bipolar patients (Cohen's d between 0.46 and 0.62). In contrast, suicide attempters did not differ from non-attempters. This significant association between CC volumes and bipolar disorders was mainly found in the male sample, while a trend was found in the female sample. Within each patient group, medication had no major effect. Our study adds to the growing body of evidence linking corpus callosum alterations and bipolar disorders.

Gray and white matter trajectories in patients with bipolar disorder

OBJECTIVES

Findings on brain structural abnormalities in patients with bipolar disorder (BP) are inconsistent and little is known about age-related evolution of these changes. We employed a cross-sectional, case-control study to compare structural age-related brain trajectories in patients with BP and healthy control subjects (HC) over a period of approximately 50 years. The primary aim was to understand whether white (WM) and gray matter (GM) abnormalities are present from the beginning of the illness and how they change over time.

METHODS

Seventy-eight patients with BP and 78 HC matched for age, gender, and educational level underwent a high-resolution structural magnetic resonance imaging protocol. A voxel-based morphometry (VBM) analysis was used to capture GM and WM differences between subjects with BP and HC. Factorial analysis of covariance was used to compare brain volume alterations at different ages between the groups.

RESULTS

We found an age-related atrophy in GM and WM volumes both in patients with BP and HC. A main effect of diagnosis emerged in the posterior cingulate cortex bilaterally, in the right thalamus, in the cerebellum bilaterally, and in the left posterior limb of the internal capsule. No interaction between diagnosis and age emerged, indicating that the volumes of these areas were permanently reduced in subjects with BP throughout the entire age range under investigation.

CONCLUSIONS

Brain alterations in patients with BP are present from the beginning of the illness and remain stable over time. All the affected areas are involved in mood and psychomotor control process. This suggests a possible neurodevelopmental involvement in the mechanism of BP.

Corpus callosum area in patients with bipolar disorder with and without psychotic features: an international multicentre study

BACKGROUND

Previous studies have reported MRI abnormalities of the corpus callosum (CC) in patients with bipolar disorder (BD), although only a few studies have directly compared callosal areas in psychotic versus nonpsychotic patients with this disorder. We sought to compare regional callosal areas in a large international multicentre sample of patients with BD and healthy controls.

METHODS

We analyzed anatomic T1 MRI data of patients with BD-I and healthy controls recruited from 4 sites (France, Germany, Ireland and the United States). We obtained the mid-sagittal areas of 7 CC subregions using an automatic CC delineation. Differences in regional callosal areas between patients and controls were compared using linear mixed models (adjusting for age, sex, handedness, brain volume, history of alcohol abuse/dependence, lithium or antipsychotic medication status, symptomatic status and site) and multiple comparisons correction. We also compared regional areas of the CC between patients with BD with and without a history of psychotic features.

RESULTS

We included 172 patients and 146 controls in our study. Patients with BD had smaller adjusted mid-sagittal CC areas than controls along the posterior body, the isthmus and the splenium of the CC. Patients with a positive history of psychotic features had greater adjusted area of the rostral CC region than those without a history of psychotic features.

LIMITATIONS

We found small to medium effect sizes, and there was no calibration technique among the sites.

CONCLUSION

Our results suggest that BD with psychosis is associated with a different pattern of interhemispheric connectivity than BD without psychosis and could be considered a relevant neuroimaging subtype of BD.

Resilience and corpus callosum microstructure in adolescence

BACKGROUND

Resilience is the capacity of individuals to resist mental disorders despite exposure to stress. Little is known about its neural underpinnings. The putative variation of white-matter microstructure with resilience in adolescence, a critical period for brain maturation and onset of high-prevalence mental disorders, has not been assessed by diffusion tensor imaging (DTI). Lower fractional anisotropy (FA) though, has been reported in the corpus callosum (CC), the brain's largest white-matter structure, in psychiatric and stress-related conditions. We hypothesized that higher FA in the CC would characterize stress-resilient adolescents.

METHOD

Three groups of adolescents recruited from the community were compared: resilient with low risk of mental disorder despite high exposure to lifetime stress (n = 55), at-risk of mental disorder exposed to the same level of stress (n = 68), and controls (n = 123). Personality was assessed by the NEO-Five Factor Inventory (NEO-FFI). Voxelwise statistics of DTI values in CC were obtained using tract-based spatial statistics. Regional projections were identified by probabilistic tractography.

RESULTS

Higher FA values were detected in the anterior CC of resilient compared to both non-resilient and control adolescents. FA values varied according to resilience capacity. Seed regional changes in anterior CC projected onto anterior cingulate and frontal cortex. Neuroticism and three other NEO-FFI factor scores differentiated non-resilient participants from the other two groups.

CONCLUSION

High FA was detected in resilient adolescents in an anterior CC region projecting to frontal areas subserving cognitive resources. Psychiatric risk was associated with personality characteristics. Resilience in adolescence may be related to white-matter microstructure.

Corpus callosal morphology in youth with bipolar depression

OBJECTIVES

Recent evidence has demonstrated that corpus callosum maturation follows a similar developmental timeline to cognitive processes. Bipolar disorder (BD) has been associated with disruptions in error processing, response inhibition, and motor functioning, which are mediated by underlying white matter structures, including the corpus callosum. Disruptions in white matter integrity have been demonstrated in BD. However, it is unknown whether alterations in the developmental trajectory of the corpus callosum may contribute to cognitive impairments in the disorder.

METHODS

We assessed the area of the corpus callosum and its subregions (the genu, rostral body, anterior and posterior bodies, isthmus, and splenium) in 14 treatment-naïve adolescents with BD (<21 years of age and in the depressed phase) and 18 healthy adolescent controls.

RESULTS

In comparison with healthy controls, participants with BD demonstrated a significantly reduced overall corpus callosum area. We also noted smaller areas in the anterior and posterior mid-body of the corpus callosum in adolescents with BD.

CONCLUSIONS

Our results suggest that commissural fibers of the corpus callosum are disrupted in early-onset BD. Specific decreases in the anterior and posterior mid-body callosal aspects may contribute to motor organization and inhibition deficits seen in BD. These findings are consistent with the involvement of inter-hemispheric tracts in early-onset BD, which may reflect an early deviation in white matter development.

Corpus callosum size is highly heritable in humans, and may reflect distinct genetic influences on ventral and rostral regions

Anatomical differences in the corpus callosum have been found in various psychiatric disorders, but data on the genetic contributions to these differences have been limited. The current study used morphometric MRI data to assess the heritability of corpus callosum size and the genetic correlations among anatomical sub-regions of the corpus callosum among individuals with and without mood disorders. The corpus callosum (CC) was manually segmented at the mid-sagittal plane in 42 women (healthy, n = 14; major depressive disorder, n = 15; bipolar disorder, n = 13) and their 86 child or adolescent offspring. Four anatomical sub-regions (CC-genu, CC2, CC3 and CC-splenium) and total CC were measured and analyzed. Heritability and genetic correlations were estimated using a variance components method, with adjustment for age, sex, diagnosis, and diagnosis x age, where appropriate. Significant heritability was found for several CC sub-regions (P<0.01), with estimated values ranging from 48% (splenium) to 67% (total CC). There were strong and significant genetic correlations among most sub regions. Correlations between the genu and mid-body, between the genu and total corpus callosum, and between anterior and mid body were all >90%, but no significant genetic correlations were detected between ventral and rostral regions in this sample. Genetic factors play an important role in corpus callosum size among individuals. Distinct genetic factors seem to be involved in caudal and rostral regions, consistent with the divergent functional specialization of these brain areas.

White-matter microstructure and gray-matter volumes in adolescents with subthreshold bipolar symptoms

Abnormalities in white-matter (WM) microstructure, as lower fractional anisotropy (FA), have been reported in adolescent-onset bipolar disorder and in youth at familial risk for bipolarity. We sought to determine whether healthy adolescents with subthreshold bipolar symptoms (SBP) would have early WM microstructural alterations and whether those alterations would be associated with differences in gray-matter (GM) volumes. Forty-two adolescents with three core manic symptoms and no psychiatric diagnosis, and 126 adolescents matched by age and sex, with no psychiatric diagnosis or symptoms, were identified after screening the IMAGEN database of 2223 young adolescents recruited from the general population. After image quality control, voxel-wise statistics were performed on the diffusion parameters using tract-based spatial statistics in 25 SBP adolescents and 77 controls, and on GM and WM images using voxel-based morphometry in 30 SBP adolescents and 106 controls. As compared with healthy controls, adolescents with SBP displayed lower FA values in a number of WM tracts, particularly in the corpus callosum, cingulum, bilateral superior and inferior longitudinal fasciculi, uncinate fasciculi and corticospinal tracts. Radial diffusivity was mainly higher in posterior parts of bilateral superior and inferior longitudinal fasciculi, inferior fronto-occipital fasciculi and right cingulum. As compared with controls, SBP adolescents had lower GM volume in the left anterior cingulate region. This is the first study to investigate WM microstructure and GM morphometric variations in adolescents with SBP. The widespread FA alterations in association and projection tracts, associated with GM changes in regions involved in mood disorders, suggest altered structural connectivity in those adolescents.

Corpus callosum changes in euthymic bipolar affective disorder

BACKGROUND

Changes in corpus callosum area and thickness have been reported in bipolar disorder. Imaging and limited neuropathological data suggest possible abnormalities in myelination and/or glial function.

AIMS

To compare corpus callosum area, thickness and magnetic resonance imaging (MRI) T1 signal intensity in patients with bipolar disorder and healthy controls.

METHOD

A total of 48 patients with euthymic bipolar disorder and 46 healthy controls underwent MRI analysis of callosal midsagittal area, callosal thickness and T1 signal intensity.

RESULTS

The bipolar group had smaller overall and subregional callosal areas and correspondingly reduced callosal width than the control group. Age correlated negatively with callosal area in the control group but not in the bipolar group. Signal intensity was higher in women than in men in both groups. Signal intensity was reduced in women, but not in men, in the bipolar group.

CONCLUSIONS

Observed differences probably relate to diagnosis rather than mood state and bipolar disorder appears to result in morphometric change that overrides changes seen in normal ageing. Intensity changes are consistent with possible altered myelination or glial function. A gender-dependent factor appears to operate and to interact with diagnosis.

A comparative diffusion tensor imaging study of corpus callosum subregion integrity in bipolar disorder and schizophrenia

Structural magnetic resonance imaging (MRI) studies have provided evidence for corpus callosum (CC) white matter abnormalities in bipolar disorder (BD) and schizophrenia (SZ). These findings include alterations in shape, volume, white matter intensity and structural integrity compared to healthy control populations. Although CC alterations are implicated in both SZ and BD, no study of which we are aware has investigated callosal subregion differences between these two patient populations. We used diffusion tensor imaging (DTI) to assess CC integrity in patients with BD (n=16), SZ (n=19) and healthy controls (HC) (n=24). Fractional anisotropy (FA) of CC subregions was measured using region of interest (ROI) analysis and compared in the three groups. Significant group differences of FA values were revealed in five CC subregions, including the anterior genu, middle genu, posterior genu, posterior body and anterior splenium. FA values of the same subregions were significantly reduced in patients with SZ compared with HC. FA values were also significantly reduced in patients with BD compared to the HC group in the same subregions, excepting the middle genu. No significant difference was found between patient groups in any region. Most of the alterations in CC subregions were present in both the BD and SZ groups. These results imply an overlap in potential pathology, possibly relating to risk factors common to both disorders. The one region that differed between patient groups, the middle genu area, may serve as an illness marker and is perhaps involved in the different cognitive impairments observed in BD and SZ.

Childhood maltreatment and corpus callosum volume in recently diagnosed patients with bipolar I disorder: data from the Systematic Treatment Optimization Program for Early Mania (STOP-EM)

Childhood trauma (CT) has been associated with abnormalities in the corpus callosum (CC). Decreased CC volumes have been reported in children and adolescents with trauma as well as adults with CT compared to healthy controls. CC morphology is potentially susceptible to the effects of Bipolar Disorder (BD) itself. Therefore, we evaluated the relationship between CT and CC morphology in BD. We using magnetic resonance imaging in 53 adults with BD recently recovered from their first manic episode, with (n = 23) and without (n = 30) CT, defined using the Childhood Trauma Questionnaire (CTQ) and 16 healthy controls without trauma. ANCOVA was performed with age, gender and intracranial volume as covariates in order to evaluate group differences in CC volume. The total CC volume was found to be smaller in BD patients with trauma compared to BD patients without trauma (p < .05). The differences were more pronounced in the anterior region of the CC. There was a significant negative correlation between CTQ scores and total CC volume in BD patients with trauma (p = .01). We did not find significant differences in the CC volume of patients with/without trauma compared to the healthy subjects. Our sample consists of patients recovered from a first episode of mania and are early in the course of illness and reductions in CC volume may occur late in the course of BD. It might mean there may be two sources of CC volume reduction in these patients: the reduction due to trauma, and the further reduction due to the illness.

White matter metabolism differentiates schizophrenia and bipolar disorder: a preliminary PET study

Fluorodeoxyglucose-F18 positron emission tomography studies (FDG-PET) have shown similar corticolimbic metabolic dysregulation in bipolar disorder and schizophrenia, with hypoactive prefrontal cortex coupled with hyperactive anterior limbic areas. However, it is not clear whether white matter metabolism connecting these regions is differently affected in the two disorders. Twenty-six patients with schizophrenia (mean age ± S.D.=30.23 ± 9.7 year-old; 19 males; mean weight ± S.D.=71 ± 3 kg) and 26 patients with bipolar disorder (mean age ± S.D.=48.73 ± 13 year-old; 18 males; mean weight ± S.D.=75 ± 15 kg) underwent an FDG-PET scan. Normalized datasets the two groups of patients were compared on a voxel-by-voxel basis using a two-sample t statistic test as implemented in SPM8, and adding age as covariate. Group differences were assessed applying a threshold of p<0.0005. White matter metabolic rates significantly differed between schizophrenia and bipolar disorder, whereas no differences were shown for cortical activity. This is the first FDG-PET, to our best knowledge, directly comparing subjects with schizophrenia to those with bipolar disorder. It reports decreased activity in the center of large fronto-temporal and cerebellar white matter tracts in patients with schizophrenia in respect to those with bipolar disorder. This feature may characterize and differentiate the regional brain metabolism of the two illnesses.

Can long-term outcomes be improved by shortening the duration of untreated illness in psychiatric disorders? A conceptual framework

The duration of untreated illness (DUI), meaning the latency to the pharmacological treatment, has been increasingly investigated in the last decade as a predictor of outcome across different psychiatric conditions, particularly in psychotic disorders. DUI is essentially computed by subtracting the age of onset of a specific disorder from the age at which the first adequate pharmacological treatment is administered. Assessment of the latency to treatment represents one of the first steps in planning early interventions. This review examines the role of the DUI in psychotic and affective disorders, focusing on neuropathological, epidemiologic, clinical and prognostic factors related to a longer latency to treatment. Through a Medline and Cochrane Library search, relevant studies up to June 2011 and other pertinent articles including meta-analyses, randomized controlled trials, naturalistic studies and clinical reviews were identified. Converging evidence indicates that a prolonged DUI negatively influences the outcome of first-episode psychosis and schizophrenia in different ways, and increasing data point toward a similar conclusion in affective disorders. Even though methodological limitations related to investigation of the DUI need to be considered, research and interventions aimed to reduce latency to treatments are object of increasing implementation worldwide. The assessment of the DUI represents one of the most important parameters to consider in this perspective, in order to quantify different latency to treatment in specific disorders and to plan related, targeted interventions.

[Age at Onset as a Marker of Subtypes of Manic-Depressive Illness]

INTRODUCTION

Age at onset of bipolar disorder has been reported as a variable that may be associated with different clinical subtypes.

OBJECTIVE

To identify patterns in the distributions of age at onset of bipolar disease and to determine whether age at onset is associated with specific clinical characteristics.

METHODS

Admixture analysis was applied to identify bipolar disorder subtypes according to age at onset. The EMUN scale was used to evaluate clinical characteristics and principal components were estimated to evaluate the relationship between subtypes according to age at onset and symptoms in the acute in the acute phase, using multivariable analyses.

RESULTS

According to age at onset, three distributions have been found: early onset: 17.7 years (S.D. 2.4); intermediate-onset: 23.9 years (S.D. 5.6); late onset: 42.8 years (S.D. 12.1). The late-onset group is antisocial, with depressive symptoms, thinking and language disorders, and socially disruptive behaviors.

CONCLUSIONS

In patients having bipolar disorder, age at onset is antisocial with three groups having specific clinical characteristics.

Cortico-cerebellar abnormalities in adolescents with heavy marijuana use

There are currently no studies that have evaluated the motor network, including the cerebellum, in adolescent marijuana (MJ) smokers. The current study aimed to evaluate whether there were activation differences in Brodmann's area 4 (BA4), Brodmann's area 6 (BA6), cingulate (CG) and cerebellum between MJ-using adolescents and healthy controls (HC) on a functional magnetic resonance imaging (fMRI) bilateral finger-tapping task. Twenty-four adolescents (aged 18.2 ± 0.7 years) with heavy MJ use and 24 HC (18.0 ± 1.9) had MRI scans on a 3T Siemens scanner, including a standard bilateral fMRI finger-tapping sequence. Imaging data were analyzed using SPM5 in Matlab. As regions of interest, BA4, BA6, cingulate (CG) and cerebellum were selected, and significant clusters of activity were thresholded at p<0.05, corrected. Healthy controls had significantly greater activation than MJ users for the CG and cerebellum. In addition, activation of the cerebellum and CG correlated with lifetime MJ smokes. This is one of the first studies to evaluate cortico-cerebellar circuits in adolescents with heavy MJ use. The study, which used a bilateral finger-tapping fMRI task, provides evidence for both CG and cerebellar dysfunction in MJ abuse and indicates that lifetime MJ use may impact the developing brain.

Neuroprogression in bipolar disorder

OBJECTIVE

Recent theories regarding the neuropathology of bipolar disorder suggest that both neurodevelopmental and neurodegenerative processes may play a role. While magnetic resonance imaging has provided significant insight into the structural, functional, and connectivity abnormalities associated with bipolar disorder, research assessing longitudinal changes has been more limited. However, such research is essential to elucidate the pathophysiology of the disorder. The aim of our review is to examine the extant literature for developmental and progressive structural and functional changes in individuals with and at risk for bipolar disorder.

METHODS

We conducted a literature review using MEDLINE and the following search terms: bipolar disorder, risk, child, adolescent, bipolar offspring, MRI, fMRI, DTI, PET, SPECT, cross-sectional, longitudinal, progressive, and developmental. Further relevant articles were identified by cross-referencing with identified manuscripts.

CONCLUSIONS

There is some evidence for developmental and progressive neurophysiological alterations in bipolar disorder, but the interpretation of correlations between neuroimaging findings and measures of illness exposure or age in cross-sectional studies must be performed with care. Prospective longitudinal studies placed in the context of normative developmental and atrophic changes in neural structures and pathways thought to be involved in bipolar disorder are needed to improve our understanding of the neurodevelopmental underpinnings and progressive changes associated with bipolar disorder.

Effects of medication on neuroimaging findings in bipolar disorder: an updated review

OBJECTIVE

Neuroimaging is an important tool for better understanding the neurobiological underpinnings of bipolar disorder (BD). However, potential study participants are often receiving psychotropic medications which can possibly confound imaging data. To better interpret the results of neuroimaging studies in BD, it is important to understand the impact of medications on structural magnetic resonance imaging (sMRI), functional MRI (fMRI), and diffusion tensor imaging (DTI).

METHODS

To better understand the impact of medications on imaging data, we conducted a literature review and searched MEDLINE for papers that included the key words bipolar disorder and fMRI, sMRI, or DTI. The search was limited to papers that assessed medication effects and had not been included in a previous review by Phillips et al. (Medication effects in neuroimaging studies of bipolar disorder. Am J Psychiatry 2008; 165: 313-320). This search yielded 74 sMRI studies, 46 fMRI studies, and 15 DTI studies.

RESULTS

Medication appeared to influence many sMRI studies, but had limited impact on fMRI and DTI findings. From the structural studies, the most robust finding (20/45 studies) was that lithium was associated with increased volumes in areas important for mood regulation, while antipsychotic agents and anticonvulsants were generally not. Regarding secondary analysis of the medication effects of fMRI and DTI studies, few showed significant effects of medication, although rigorous analyses were typically not possible when the majority of subjects were medicated. Medication effects were more frequently observed in longitudinal studies designed to assess the impact of particular medications on the blood oxygen level-dependent (BOLD) signal. With a few exceptions, the observed effects were normalizing, meaning that the medicated individuals with BD were more similar than their unmedicated counterparts to healthy subjects.

CONCLUSIONS

The effects of psychotropic medications, when present, are predominantly normalizing and thus do not seem to provide an alternative explanation for differences in volume, white matter tracts, or BOLD signal between BD participants and healthy subjects. However, the normalizing effects of medication could obfuscate differences between BD and healthy subjects, and thus might lead to type II errors.

Suicidal behavior is associated with reduced corpus callosum area

BACKGROUND

Corpus callosum (CC) size has been associated with cognitive and emotional deficits in a range of neuropsychiatric and mood disorders. As such deficits are also found in suicidal behavior, we investigated specifically the association between CC atrophy and suicidal behavior.

METHODS

We studied 435 right-handed individuals without dementia from a cohort of community-dwelling persons aged 65 years and over (the ESPRIT study). They were divided in three groups: suicide attempters (n = 21), affective control subjects (AC) (n = 180) without history of suicide attempt but with a history of depression, and healthy control subjects (HC) (n = 234). T1-weighted magnetic resonance images were traced to measure the midsagittal areas of the anterior, mid, and posterior CC. Multivariate analysis of covariance was used to compare CC areas in the three groups.

RESULTS

Multivariate analyses adjusted for age, gender, childhood trauma, head trauma, and total brain volume showed that the area of the posterior third of CC was significantly smaller in suicide attempters than in AC (p = .020) and HC (p = .010) individuals. No significant differences were found between AC and HC. No differences were found for the anterior and mid thirds of the CC.

CONCLUSIONS

Our findings emphasize a reduced size of the posterior third of the CC in subjects with a history of suicide, suggesting a diminished interhemispheric connectivity and a possible role of CC in the pathophysiology of suicidal behavior. Further studies are needed to strengthen these results and clarify the underlying cellular changes leading to these morphometric differences.

Structural brain and neuropsychometric changes associated with pediatric bipolar disorder with psychosis

OBJECTIVES

To identify neuropsychological and structural brain changes using a combination of high-resolution structural and diffusion tensor imaging in pediatric bipolar disorder (PBD) with psychosis (presence of delusions and or hallucinations).

METHODS

We recruited 15 patients and 20 euthymic age- and gender-matched healthy controls. All subjects underwent high-resolution structural and diffusion tensor imaging. Voxel-based morphometry (VBM), tract-based spatial statistics (TBSS), and probabilistic tractography were used to analyse magnetic resonance imaging data.

RESULTS

The PBD subjects had normal overall intelligence with specific impairments in working memory, executive function, language function, and verbal memory. Reduced gray matter (GM) density was found in the left orbitofrontal cortex, left pars triangularis, right premotor cortex, occipital cortex, right occipital fusiform gyrus, and right crus of the cerebellum. TBSS analysis showed reduced fractional anisotropy (FA) in the anterior corpus callosum. Probabilistic tractography from this cluster showed that this region of the corpus callosum is connected with the prefrontal cortices, including those regions whose density is decreased in PBD. In addition, FA change was correlated with verbal memory and working memory, while more widespread reductions in GM density correlated with working memory, executive function, language function, and verbal memory.

CONCLUSIONS

The findings suggest widespread cortical changes as well as specific involvement of interhemispheric prefrontal tracts in PBD, which may reflect delayed myelination in these tracts.