Is cerebellar volume related to bipolar disorder?

The cerebellum and psychiatric disorders

The cerebellum has been considered for a long time to play a role solely in motor coordination. However, studies over the past two decades have shown that the cerebellum also plays a key role in many motor, cognitive, and emotional processes. In addition, studies have also shown that the cerebellum is implicated in many psychiatric disorders including attention deficit hyperactivity disorder, autism spectrum disorders, schizophrenia, bipolar disorder, major depressive disorder, and anxiety disorders. In this review, we discuss existing studies reporting cerebellar dysfunction in various psychiatric disorders. We will also discuss future directions for studies linking the cerebellum to psychiatric disorders.

Dysregulation of miR-34a links neuronal development to genetic risk factors for bipolar disorder

Bipolar disorder (BD) is a heritable neuropsychiatric disorder with largely unknown pathogenesis. Given their prominent role in brain function and disease, we hypothesized that microRNAs (miRNAs) might be of importance for BD. Here we show that levels of miR-34a, which is predicted to target multiple genes implicated as genetic risk factors for BD, are increased in postmortem cerebellar tissue from BD patients, as well as in BD patient-derived neuronal cultures generated by reprogramming of human fibroblasts into induced neurons or into induced pluripotent stem cells (iPSCs) subsequently differentiated into neurons. Of the predicted miR-34a targets, we validated the BD risk genes ankyrin-3 (ANK3) and voltage-dependent L-type calcium channel subunit beta-3 (CACNB3) as direct miR-34a targets. Using human iPSC-derived neuronal progenitor cells, we further show that enhancement of miR-34a expression impairs neuronal differentiation, expression of synaptic proteins and neuronal morphology, whereas reducing endogenous miR-34a expression enhances dendritic elaboration. Taken together, we propose that miR-34a serves as a critical link between multiple etiological factors for BD and its pathogenesis through the regulation of a molecular network essential for neuronal development and synaptogenesis.

Implicit motor learning in bipolar disorder

OBJECTIVES

A growing number of publications describe cerebellar abnormalities in patients with bipolar disorder (BD). The aim of the following paper was to examine the functional aspects of that issue by focusing on implicit learning - a cognitive function with significant cerebellar underpinnings.

METHODS

27 patients with BD and 26 healthy controls (HC), matched for age and sex took part in the study. Implicit motor learning was assessed by the serial reaction time task (SRTT), in which participants were unconsciously learning a sequence of motor reactions. The indicators of procedural learning were the decrease of reaction time (RT) across the repetition of the sequence and the rebound of RT when the sequence changed into a random set of stimuli.

RESULTS

BD patients did not present any indicators of the implicit learning, their RT increased across repetitions of the sequence and it decreased when the sequence changed to random. Contrary, in the control group RT decreased across the sequence repetitions and increased when the stimuli begun to appear randomly.

LIMITATIONS

A low subject count and a non-drug naïve patients group, medicated with atypical antipsychotic and mood stabilizers, are the most significant limitations of this study.

CONCLUSIONS

BD patients did not acquire procedural knowledge while performing the task, whereas HC did. To our knowledge this is the first study that shows the impairment of implicit motor learning in patients with BD. This indicates the possible cerebellar dysfunction in this disease and may provide a new neuropsychiatric approach to bipolar disorder.

Abnormal development of monoaminergic neurons is implicated in mood fluctuations and bipolar disorder

Subtle mood fluctuations are normal emotional experiences, whereas drastic mood swings can be a manifestation of bipolar disorder (BPD). Despite their importance for normal and pathological behavior, the mechanisms underlying endogenous mood instability are largely unknown. During embryogenesis, the transcription factor Otx2 orchestrates the genetic networks directing the specification of dopaminergic (DA) and serotonergic (5-HT) neurons. Here we behaviorally phenotyped mouse mutants overexpressing Otx2 in the hindbrain, resulting in an increased number of DA neurons and a decreased number of 5-HT neurons in both developing and mature animals. Over the course of 1 month, control animals exhibited stable locomotor activity in their home cages, whereas mutants showed extended periods of elevated or decreased activity relative to their individual average. Additional behavioral paradigms, testing for manic- and depressive-like behavior, demonstrated that mutants showed an increase in intra-individual fluctuations in locomotor activity, habituation, risk-taking behavioral parameters, social interaction, and hedonic-like behavior. Olanzapine, lithium, and carbamazepine ameliorated the behavioral alterations of the mutants, as did the mixed serotonin receptor agonist quipazine and the specific 5-HT2C receptor agonist CP-809101. Testing the relevance of the genetic networks specifying monoaminergic neurons for BPD in humans, we applied an interval-based enrichment analysis tool for genome-wide association studies. We observed that the genes specifying DA and 5-HT neurons exhibit a significant level of aggregated association with BPD but not with schizophrenia or major depressive disorder. The results of our translational study suggest that aberrant development of monoaminergic neurons leads to mood fluctuations and may be associated with BPD.

Cerebellar volume in schizophrenia and bipolar I disorder with and without psychotic features

OBJECTIVE

There is growing evidence that cerebellum plays a crucial role in cognition and emotional regulation. Cerebellum is likely to be involved in the physiopathology of both bipolar disorder and schizophrenia. The objective of our study was to compare cerebellar size between patients with bipolar disorder, patients with schizophrenia, and healthy controls in a multicenter sample. In addition, we studied the influence of psychotic features on cerebellar size in patients with bipolar disorder.

METHOD

One hundred and fifteen patients with bipolar I disorder, 32 patients with schizophrenia, and 52 healthy controls underwent 3 Tesla MRI. Automated segmentation of cerebellum was performed using FreeSurfer software. Volumes of cerebellar cortex and white matter were extracted. Analyses of covariance were conducted, and age, sex, and intracranial volume were considered as covariates.

RESULTS

Bilateral cerebellar cortical volumes were smaller in patients with schizophrenia compared with patients with bipolar I disorder and healthy controls. We found no significant difference of cerebellar volume between bipolar patients with and without psychotic features. No change was evidenced in white matter.

CONCLUSION

Our results suggest that reduction in cerebellar cortical volume is specific to schizophrenia. Cerebellar dysfunction in bipolar disorder, if present, appears to be more subtle than a reduction in cerebellar volume.

Disturbed spontaneous brain-activity pattern in patients with optic neuritis using amplitude of low-frequency fluctuation: a functional magnetic resonance imaging study

OBJECTIVE

To use the amplitude of low-frequency fluctuation (ALFF) technique to investigate the local features of spontaneous brain activity in optic neuritis (ON) and their relationship with behavioral performance.

MATERIALS AND METHODS

Twelve patients with ON (four male, eight female) and twelve age-, sex-, and education status-matched healthy controls (HCs) (four male, eight female) underwent resting-state functional magnetic resonance imaging (rs-fMRI) scans. The ALFF technique was used to assess local features of spontaneous brain activity. Correlation analysis was used to explore the relationship between the observed mean ALFF values of the different areas and visual evoked potentials (VEPs) in patients with ON.

RESULTS

Compared with HCs, patients with ON had significantly decreased ALFF values in the posterior and anterior lobes of the right cerebellum, right putamen, right inferior frontal gyrus, right insula, right supramarginal gyrus, right inferior parietal lobule, left medial frontal gyrus, left superior temporal gyrus, bilateral anterior cingulate/medial frontal gyrus, and bilateral precuneus, and significantly increased ALFF values in the posterior lobes of the left and right cerebellum, right inferior temporal gyrus, right inferior temporal/fusiform gyrus, left parahippocampal gyrus, left fusiform gyrus, left calcarine fissure, left inferior parietal lobule, and left cuneus. We found negative correlations between the mean ALFF signal value of the left parahippocampal gyrus and the VEP amplitude of the right eye in ON (r=-0.584, P=0.046), and a positive correlation between the mean ALFF signal value of the bilateral precuneus and the best-corrected visual acuity of the left eye (r=0.579, P=0.048) in patients with ON.

CONCLUSION

ON mainly seems to involve dysfunction in the default-mode network, cerebellum, and limbic system, which may reflect the underlying pathologic mechanism of ON.

Altered intrinsic regional spontaneous brain activity in patients with optic neuritis: a resting-state functional magnetic resonance imaging study

OBJECTIVE

To investigate the underlying regional homogeneity (ReHo) in brain-activity deficit in patients with optic neuritis (ON) and its relationship with behavioral performance.

MATERIALS AND METHODS

In total, twelve patients with ON (four males and eight females) and twelve (four males and eight females) age-, sex-, and education-matched healthy controls underwent resting-state functional magnetic resonance imaging scans. The ReHo method was used to assess the local features of spontaneous brain activity. Correlation analysis was used to explore the relationship between the observed mean ReHo values of the different brain areas and the visual evoked potential (VEP) in patients with ON.

RESULTS

Compared with the healthy controls, patients with ON showed lower ReHo in the left cerebellum, posterior lobe, left middle temporal gyrus, right insula, right superior temporal gyrus, left middle frontal gyrus, bilateral anterior cingulate cortex, left superior frontal gyrus, right superior frontal gyrus, and right precentral gyrus, and higher ReHo in the cluster of the left fusiform gyrus and right inferior parietal lobule. Meanwhile, we found that the VEP amplitude of the right eye in patients with ON showed a positive correlation with the ReHo signal value of the left cerebellum posterior lobe (r=0.701, P=0.011), the right superior frontal gyrus (r=0.731, P=0.007), and the left fusiform gyrus (r=0.644, P=0.024). We also found that the VEP latency of the right eye in ON showed a positive correlation with the ReHo signal value of the right insula (r=0.595, P=0.041).

CONCLUSION

ON may involve dysfunction in the default-mode network, which may reflect the underlying pathologic mechanism.

Individual differences in response to positive and negative stimuli: endocannabinoid-based insight on approach and avoidance behaviors

Approach and avoidance behaviors-the primary responses to the environmental stimuli of danger, novelty and reward-are associated with the brain structures that mediate cognitive functionality, reward sensitivity and emotional expression. Individual differences in approach and avoidance behaviors are modulated by the functioning of amygdaloid-hypothalamic-striatal and striatal-cerebellar networks implicated in action and reaction to salient stimuli. The nodes of these networks are strongly interconnected and by acting on them the endocannabinoid and dopaminergic systems increase the intensity of appetitive or defensive motivation. This review analyzes the approach and avoidance behaviors in humans and rodents, addresses neurobiological and neurochemical aspects of these behaviors, and proposes a possible synaptic plasticity mechanism, related to endocannabinoid-dependent long-term potentiation (LTP) and depression that allows responding to salient positive and negative stimuli.

The correlation between emotional intelligence and gray matter volume in university students

A number of recent studies have investigated the neurological substrates of emotional intelligence (EI), but none of them have considered the neural correlates of EI that are measured using the Schutte Self-Report Emotional Intelligence Scale (SSREIS). This scale was developed based on the EI model of Salovey and Mayer (1990). In the present study, SSREIS was adopted to estimate EI. Meanwhile, magnetic resonance imaging (MRI) and voxel-based morphometry (VBM) were used to evaluate the gray matter volume (GMV) of 328 university students. Results found positive correlations between Monitor of Emotions and VBM measurements in the insula and orbitofrontal cortex. In addition, Utilization of Emotions was positively correlated with the GMV in the parahippocampal gyrus, but was negatively correlated with the VBM measurements in the fusiform gyrus and middle temporal gyrus. Furthermore, Social Ability had volume correlates in the vermis. These findings indicate that the neural correlates of the EI model, which primarily focuses on the abilities of individuals to appraise and express emotions, can also regulate and utilize emotions to solve problems.

Neurobiological risk factors for suicide: insights from brain imaging

CONTEXT

This article reviews neuroimaging studies on neural circuitry associated with suicide-related thoughts and behaviors to identify areas of convergence in findings. Gaps in the literature for which additional research is needed are identified.

EVIDENCE ACQUISITION

A PubMed search was conducted and articles published before March 2014 were reviewed that compared individuals who made suicide attempts to those with similar diagnoses who had not made attempts or to healthy comparison subjects. Articles on adults with suicidal ideation and adolescents who had made attempts, or with suicidal ideation, were also included. Reviewed imaging modalities included structural magnetic resonance imaging, diffusion tensor imaging, single photon emission computed tomography, positron emission tomography, and functional magnetic resonance imaging.

EVIDENCE SYNTHESIS

Although many studies include small samples, and subject characteristics and imaging methods vary across studies, there were convergent findings involving the structure and function of frontal neural systems and the serotonergic system.

CONCLUSIONS

These initial neuroimaging studies of suicide behavior have provided promising results. Future neuroimaging efforts could be strengthened by more strategic use of common data elements and a focus on suicide risk trajectories. At-risk subgroups defined by biopsychosocial risk factors and multidimensional assessment of suicidal thoughts and behaviors may provide a clearer picture of the neural circuitry associated with risk status-both current and lifetime. Also needed are studies investigating neural changes associated with interventions that are effective in risk reduction.

Brain regions associated with risk and resistance for bipolar I disorder: a voxel-based MRI study of patients with bipolar disorder and their healthy siblings

OBJECTIVE

Bipolar I disorder is a highly heritable disorder but not all siblings manifest with the illness, even though they may share similar genetic and environmental risk factors. Thus, sibling studies may help to identify brain structural endophenotypes associated with risk and resistance for the disorder.

METHODS

Structural magnetic resonance imaging (MRI) scans were acquired for 28 euthymic patients with bipolar disorder, their healthy siblings, and 30 unrelated healthy controls. Statistical Parametric Mapping 8 (SPM8) was used to identify group differences in regional gray matter volume by voxel-based morphometry (VBM).

RESULTS

Using analysis of covariance, gray matter analysis of the groups revealed a group effect indicating that the left orbitofrontal cortex [Brodmann area (BA) 11] was smaller in patients with bipolar disorder than in unrelated healthy controls [F = 14.83, p < 0.05 (family-wise error); 7 mm(3) ]. Paired t-tests indicated that the orbitofrontal cortex of patients with bipolar disorder [t = 5.19, p < 0.05 (family-wise error); 37 mm(3) ] and their healthy siblings [t = 3.89, p < 0.001 (uncorrected); 63 mm(3) ] was smaller than in unrelated healthy controls, and that the left dorsolateral prefrontal cortex was larger in healthy siblings than in patients with bipolar disorder [t = 4.28, p < 0.001 (uncorrected); 323 mm(3) ] and unrelated healthy controls [t = 4.36, p < 0.001 (uncorrected); 245 mm(3) ]. Additional region-of-interest analyses also found volume deficits in the right cerebellum of patients with bipolar disorder [t = 3.92, p < 0.001 (uncorrected); 178 mm(3) ] and their healthy siblings [t = 4.23, p < 0.001 (uncorrected); 489 mm(3) ], and in the left precentral gyrus of patients with bipolar disorder [t = 3.61, p < 0.001 (uncorrected); 115 mm(3) ] compared to unrelated healthy controls.

CONCLUSIONS

The results of this study suggest that a reduction in the volume of the orbitofrontal cortex, which plays a role in the automatic regulation of emotions and is a part of the medial prefrontal network, is associated with the heritability of bipolar disorder. Conversely, increased dorsolateral prefrontal cortex volume may be a neural marker of a resistance factor as it is part of a network of voluntary emotion regulation and balances the effects of the disrupted automatic emotion regulation system.

General and specific effects of early-life psychosocial adversities on adolescent grey matter volume

Exposure to childhood adversities (CA) is associated with subsequent alterations in regional brain grey matter volume (GMV). Prior studies have focused mainly on severe neglect and maltreatment. The aim of this study was to determine in currently healthy adolescents if exposure to more common forms of CA results in reduced GMV. Effects on brain structure were investigated using voxel-based morphometry in a cross-sectional study of youth recruited from a population-based longitudinal cohort. 58 participants (mean age = 18.4) with (n = 27) or without (n = 31) CA exposure measured retrospectively from maternal interview were included in the study. Measures of recent negative life events (RNLE) recorded at 14 and 17 years, current depressive symptoms, gender, participant/parental psychiatric history, current family functioning perception and 5-HTTLPR genotype were covariates in analyses. A multivariate analysis of adversities demonstrated a general association with a widespread distributed neural network consisting of cortical midline, lateral frontal, temporal, limbic, and cerebellar regions. Univariate analyses showed more specific associations between adversity measures and regional GMV: CA specifically demonstrated reduced vermis GMV and past psychiatric history with reduced medial temporal lobe volume. In contrast RNLE aged 14 was associated with increased lateral cerebellar and anterior cingulate GMV. We conclude that exposure to moderate levels of childhood adversities occurring during childhood and early adolescence exerts effects on the developing adolescent brain. Reducing exposure to adverse social environments during early life may optimize typical brain development and reduce subsequent mental health risks in adult life.

The Cerebellum and Premenstrual Dysphoric Disorder

The cerebellum constitutes ten percent of brain volume and contains the majority of brain neurons. Although it was historically viewed primarily as processing motoric computations, current evidence supports a more comprehensive role, where cerebro-cerebellar feedback loops also modulate various forms of cognitive and affective processing. Here we present evidence for a role of the cerebellum in premenstrual dysphoric disorder (PMDD), which is characterized by severe negative mood symptoms during the luteal phase of the menstrual cycle. Although a link between menstruation and cyclical dysphoria has long been recognized, neuroscientific investigations of this common disorder have only recently been explored. This article reviews functional and structural brain imaging studies of PMDD and the similar but less well defined condition of premenstrual syndrome (PMS). The most consistent findings are that women with premenstrual dysphoria exhibit greater relative activity than other women in the dorsolateral prefrontal cortex and posterior lobules VI and VII of the neocerebellum. Since both brain areas have been implicated in emotional processing and mood disorders, working memory and executive functions, this greater activity probably represents coactivation within a cerebro-cerebellar feedback loop regulating emotional and cognitive processing. Some of the evidence suggests that increased activity within this circuit may preserve cerebellar structure during aging, and possible mechanisms and implications of this finding are discussed.

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.

Vestibular insights into cognition and psychiatry

The vestibular system has traditionally been thought of as a balance apparatus; however, accumulating research suggests an association between vestibular function and psychiatric and cognitive symptoms, even when balance is measurably unaffected. There are several brain regions that are implicated in both vestibular pathways and psychiatric disorders. The present review examines the anatomical associations between the vestibular system and various psychiatric disorders. Despite the lack of direct evidence for vestibular pathology in the key psychiatric disorders selected for this review, there is a substantial body of literature implicating the vestibular system in each of the selected psychiatric disorders. The second part of this review provides complimentary evidence showing the link between vestibular dysfunction and vestibular stimulation upon cognitive and psychiatric symptoms. In summary, emerging research suggests the vestibular system can be considered a potential window for exploring brain function beyond that of maintenance of balance, and into areas of cognitive, affective and psychiatric symptomology. Given the paucity of biological and diagnostic markers in psychiatry, novel avenues to explore brain function in psychiatric disorders are of particular interest and warrant further exploration.

Posterior cerebellar vermal deficits in bipolar disorder

BACKGROUND

Based on growing evidence of the crucial role of the cerebellum in emotional regulation, we sought to identify cerebellar structural deficits in a large sample of patients with bipolar disorder (BD).

METHODS

Cerebellar gray matter density was examined in 49 BD patients (24 medication-naive and 25 medication-treated) and 50 carefully matched healthy individuals, using voxel-based morphometry with a high-resolution spatially unbiased atlas template of the human cerebellum. This recently developed methodology is specifically optimized for the assessment of cerebellar structures. We further explored whether antimanic treatment could attenuate cerebellar structural deficits.

RESULTS

BD patients showed a greater reduction in gray matter density of the posterior cerebellar regions, including the bilateral vermi and the right crus relative to healthy individuals (corrected p<.05). A stepwise linear reduction in gray matter density was observed in bilateral vermal regions between healthy individuals, medication-treated, and medication-naive BD patients. Furthermore, positive correlations of longer duration of illness with bilateral vermal gray matter deficits were observed only in medication-naive BD patients, but not in patients with medication history.

LIMITATIONS

This study adopted a cross-sectional design. The automatic intensity-normalization method for the measurement of cerebellar gray matter density may have a limitation in providing detailed anatomical information at a cerebellar folia level.

CONCLUSIONS

The current findings suggest that BD-related deficits in the posterior cerebellar regions, which appear to progress over the course of illness, could potentially be ameliorated by proper treatment with mood stabilizers.

Cis-acting regulation of brain-specific ANK3 gene expression by a genetic variant associated with bipolar disorder

Several genome-wide association studies for bipolar disorder (BD) have found a strong association of the Ankyrin 3 (ANK3) gene. This association spans numerous linked single-nucleotide polymorphisms (SNPs) in an ~250-kb genomic region overlapping ANK3. The associated region encompasses predicted regulatory elements as well as two of the six validated alternative first exons, which encode distinct protein domains at the N-terminus of the protein also known as Ankyrin-G. Using RNA ligase-mediated rapid amplification of cDNA ends to identify novel transcripts in conjunction with a highly sensitive, exon-specific multiplexed mRNA expression assay, we detected differential regulation of distinct ANK3 transcription start sites and coupling of specific 5' ends with 3' mRNA splicing events in postmortem human brain and human stem cell-derived neural progenitors and neurons. Furthermore, allelic variation at the BD-associated SNP rs1938526 correlated with a significant difference in cerebellar expression of a brain-specific ANK3 transcript. These findings suggest a brain-specific cis-regulatory transcriptional effect of ANK3 that may be relevant to BD pathophysiology.

White matter differences in euthymic bipolar I disorder: a combined magnetic resonance imaging and diffusion tensor imaging voxel-based study

OBJECTIVES

A broad range of subtle and markedly heterogenous neuroanatomical abnormalities of grey matter and white matter have been reported in bipolar disorder. Euthymic bipolar disorder patients represent a clinically homogenous group in which to identify trait-based biomarkers of bipolar disorder. In this study, we sought to clarify the nature and extent of neuroanatomical differences in a large, clinically homogeneous group of euthymic bipolar disorder patients.

METHODS

Structural magnetic resonance imaging (sMRI) was obtained for 60 patients with prospectively confirmed euthymic bipolar I disorder and 60 individually age- and gender-matched healthy volunteers. High angular resolution diffusion tensor imaging (DTI) scans were obtained for a subset of this sample comprising 35 patients and 43 controls. Voxel-based analysis of both sMRI and DTI data sets was performed.

RESULTS

Bipolar disorder patients displayed global reductions in white matter volume and fractional anisotropy reductions in the corpus callosum, posterior cingulum, and prefrontal white matter compared with controls. There were corresponding increases in radial diffusivity in the callosal splenium in patients compared with controls. No significant group differences were detected in grey matter. In patients, lithium was associated with a bilateral increase in grey matter volume in the temporal lobes, but not with any DTI parameter.

CONCLUSIONS

Euthymic bipolar I disorder is characterized by both diffuse global white matter deficits and potential regional disorganization in interhemispheric and longitudinal tracts, while grey matter appears to be preserved.

Cerebellar granule cells are generated postnatally in humans

How many cerebellar granule cells are generated pre- or postnatally in human is unknown. Using a rigorous design-based stereologic approach we investigated postmortem cerebella from 14 children who died between the first postnatal day (P1) and 11 months of age (M11). We found a statistically significant (p < 0.05) age-related increase in the total number of granule cells from 5.9 × 10(9) at M1 to 37.6 × 10(9) at M10/11 per cerebellar half but not in the total number of Purkinje cells (12.1 × 10(6) at M1 vs. 13.9 × 10(6) at M10/11 per cerebellar half). Accordingly, approximately 85 % of the cerebellar granule cells are generated postnatally in human, and the number of granule cells per Purkinje cell in the human cerebellum increases from 485 at M1 to 2,700 at M10/11, approximately. These data indicate that the human cerebellum has a much higher functional plasticity during the first year of life than previously thought, and may respond very sensitively to internal and external influences during this time. This has important implications for several neuropsychiatric conditions in which cerebellar involvement has been demonstrated.

Morphometric differences in central stress-regulating structures between women with and without borderline personality disorder

BACKGROUND

Experiences of early life stress, increased psychological arousal and the body's physiologic stress response seem to play an important role in the pathogenesis and maintenance of borderline personality disorder (BPD). In the present study, we investigated alterations in grey matter of central stress-regulating structures in female patients with BPD.

METHODS

We examined T1-weighted structural magnetic resonance imaging scans of unmedicated, right-handed female patients with BPD (according to DSM-IV criteria) and healthy controls matched for age, intelligence and education using fully automated DARTEL voxel-based morphometry. Our regions of interest analyses included the hippocampus, amygdala, anterior cingulate cortex (ACC) and hypothalamus.

RESULTS

We enrolled 30 patients and 33 controls in our study. The grey matter of patients with BPD was reduced in the hippocampus, but increased in the hypothalamus compared with healthy participants. Hypothalamic volume correlated positively with the history of traumatization in patients with BPD. No significant alterations were found in the amygdala and ACC.

LIMITATIONS

This study is limited by the lack of measures of corticotropin-releasing hormone, adrenocorticotropic hormone and cortisol levels. Furthermore, moderate sample size and comorbid disorders need to be considered.

CONCLUSION

Our findings provide new evidence for grey matter alterations in the hypothalamus and replicate previously reported decrements in hippocampal volume in patients with BPD. Understanding the role of the hypothalamus and other central stress-regulating structures could help us to further understand the neurobiological underpinnings of this complex disorder.

Reduced posterior corpus callosum area in suicidal and non-suicidal patients with bipolar disorder

BACKGROUND

Impulsivity is a characteristic of bipolar disorder (BD) that can contribute to the risk for suicidal behavior. Evidence suggests that gray and white matter abnormalities are linked with impulsivity, but little is known about the association between corpus callosum (CC) and impulsivity in BD. We examined the CC area and impulsivity in euthymic bipolar I patients, with and without lifetime history of suicide attempts, and in healthy controls.

METHODS

Nineteen bipolar patients with a suicide attempt history (BP-S), 21 bipolar patients without suicide attempt history (BP-NS), and 22 healthy controls (HC) underwent clinical assessment by the Structured Clinical Interview with the DSM-IV axis I (SCID-I), the Barratt Impulsiveness Scale (BIS-11), and MRI scan.

RESULTS

No differences were observed for any CC subregion between BP-S and BP-NS groups. There was a significant reduction in the genu (p=0.04) and isthmus areas (p=0.01), in bipolar patients compared with HC. In the BP-S group, the BIS-11 total (p=0.01), attention (p=0.001) and non-planning (p=0.02) impulsivity scores were significantly higher than in the BP-NS and HC groups.

LIMITATIONS

These results cannot establish causality because of the cross-sectional nature of the study.

CONCLUSION

This report potentially provides evidence that a reduction in the CC area is present even in non-symptomatic bipolar patients, which may be evidence of a biological trait marker for BD. Furthermore, the study demonstrated that BP-S group had higher impulsivity even during euthymia, which points to a sustained association between lifetime history of suicide attempts and impulsivity in BD.

Relationship between structural abnormalities in the cerebellum and dementia, posttraumatic stress disorder and bipolar disorder

New evidence suggests that the cerebellum has structural and functional abnormalities in psychiatric disorders.

Objective

In this research, the goal was to measure the volume of the cerebellum and its subregions in individuals with psychiatric disorders and to relate these findings to their symptoms.

Methods

Patients with different degrees of cognitive impairment (Epidemiology of the Elderly - UNIFESP) and patients with post-traumatic stress disorder (PTSD) from population studies were analyzed. Also, patients with bipolar disorder from an outpatient clinic (Center for the Study of Mood and Anxiety Disorders, Universidade Federal da Bahia) were recruited for this study. All subjects underwent a 1.5T structural magnetic resonance scan. Volumetric measures and symptom measurements, by psychometric scales, were performed and compared between patients and controls.

Results

The cerebellum volume was reduced in patients with cognitive impairment without dementia and with dementia, in patients with PTSD, and in patients with bipolar disorder compared to controls. In dementia and PTSD, the left cerebellar hemisphere and vermis volume were reduced. In bipolar disorder, volumes of both hemispheres and the vermis were reduced. In the first two studies, these cerebellar volumetric reductions correlated with symptoms of the disease.

Conclusion

The exact nature of cerebellar involvement in mental processes is still not fully understood. However, abnormalities in cerebellar structure and its functions have been reported in some of these diseases. Future studies with larger samples are needed to clarify these findings and investigate whether they are important for treatment and prognosis.

The cerebellum and neuropsychiatric disorders

Relative to non-human primates, in humans the cerebellum, and prefrontal cortex are brain regions which have undergone major evolutionary changes. In recent decades, progress in molecular biology and advances in the development of functional neuroimaging analysis have shown that the evolution of the human cerebellum was accompanied by the acquisition of more functions than were previously deduced from human post-mortem studies and animal experimentation. These new cerebellar functions included the control of attention and other cognitive functions, emotions and mood, and social behavior, which were all thought to represent cortical functions. The importance of this new view of cerebellar physiology has been confirmed by the frequency of neuropsychiatric disorders in individuals with cerebellar abnormalities. The information collected in this review emphasizes the importance of cerebellar studies in establishing the physiological substrate of mental diseases.

Cerebellar vermis volume in major depressive disorder

The vermis is located in the midline of the cerebellum and is involved in the regulation of affect and cognitive processes. Although changes in vermis size have been reported in several psychiatric disorders such as schizophrenia and bipolar disorder, no volumetric studies have been conducted on samples of patients with major depressive disorder (MDD). One-hundred and five adult subjects were recruited: 35 patients who were presenting for first treatment (FT; 22 females), 35 patients with known previous treatment (PT; 22 females), and 35 healthy controls (NC; 22 females), matched for age and gender. We compared the volumes of the total vermis, the anterior lobe (V1), the superior-posterior lobe (V2), and the inferior-posterior lobe (V3), among these study groups. Anterior vermis (V1) was larger in patients with MDD with a long history of antidepressant treatment compared to healthy controls. This finding was evident only in men [F(2, 36) = 9.23, p = .001]. Patients in the FT group did not differ from healthy controls in any vermian region. We found no correlations between vermian subregional volumes and clinical variables such as illness duration or age at onset of illness. We speculate that the larger anterior vermis volumes might arise from abnormalities in connectivity or as compensatory responses to the prefrontal dysfunction noted in patients with MDD but confirmation of this hypothesis awaits further studies.

The cerebellum link to neuroticism: a volumetric MRI association study in healthy volunteers

Prior research suggests an association between reduced cerebellar volumes and symptoms of depression and anxiety in patients with mood disorders. However, whether a smaller volume in itself reflects a neuroanatomical correlate for increased susceptibility to develop mood disorders remains unclear. The aim of the present study was to examine the relationship between cerebellar volume and neurotic personality traits in a non-clinical subject sample. 3T Structural magnetic resonance imaging scans were acquired, and trait depression and anxiety scales of the revised NEO personality inventory were assessed in thirty-eight healthy right-handed volunteers. Results showed that cerebellar volume corrected for total brain volume was inversely associated with depressive and anxiety-related personality traits. Cerebellar gray and white matter contributed equally to the observed associations. Our findings extend earlier clinical observations by showing that cerebellar volume covaries with neurotic personality traits in healthy volunteers. The results may point towards a possible role of the cerebellum in the vulnerability to experience negative affect. In conclusion, cerebellar volumes may constitute a clinico-neuroanatomical correlate for the development of depression- and anxiety-related symptoms.