Atrophy of the cerebellar vermis: relevance to the symptoms of schizophrenia

The Neurobiology of Formal Thought Disorder

The concept of Formal Thought Disorder (FTD) is an ambiguous and disputed one, even though it has endured as a core psychopathological construct in clinical Psychiatry. FTD can be summarized as a multidimensional construct, reflecting difficulties or idiosyncrasies in thinking, language, and communication in general and is usually subdivided into positive versus negative. In this article, we aim to explore the putative neurobiology of FTD, ranging from changes in neurotransmitter systems to alterations in the functional anatomy of the brain. We also discuss recent critiques of the operationalist view of FTD and how they might fit in its biological underpinnings. We conclude that FTD might be the observable phenotype of many distinct underlying alterations in different proportions.

The Cerebellum and Implicit Sequencing: Evidence from Cerebellar Ataxia

The cerebellum recognizes sequences from prior experiences and uses this information to generate internal models that predict future outcomes in a feedforward manner [Front Hum Neurosci 8: 475, 2014; Cortex 47: 137-44, 2011; Cerebellum 7: 611-5, 2008; J Neurosci 26: 9107-16, 2006]. This process has been well documented in the motor domain, but the cerebellum's role in cognitive sequencing, within the context of implicit versus explicit processes, is not well characterized. In this study, we tested individuals with cerebellar ataxia and healthy controls to clarify the role of the cerebellum sequencing using variations on implicit versus explicit and motor versus cognitive demands across five experiments. Converging results across these studies suggest that cerebellar feedforward mechanisms may be necessary for sequencing in the implicit domain only. In the ataxia group, rhythmic tapping, rate of motor learning, and implicit sequence learning were impaired. However, for cognitive sequencing that could be accomplished using explicit strategies, the cerebellar group performed normally, as though they shifted to extra-cerebellar mechanisms to compensate. For example, when cognitive and motor functions relied on cerebellar function simultaneously, the ataxia group's motor function was unaffected, in contrast to that of controls whose motor performance declined as a function of cognitive load. These findings indicated that the cerebellum is not critical for all forms of sequencing per se. Instead, it plays a fundamental role for sequencing within the implicit domain, whether functions are motor or cognitive. Moreover, individuals with cerebellar ataxia are generally able to compensate for cognitive sequencing when explicit strategies are available in order to preserve resources for motor function.

A systematic review of task-based functional neuroimaging studies investigating language, semantic and executive processes in thought disorder

The aim of the current systematic review was to synthesise the research that has investigated thought disorder (TD) using task-based functional neuroimaging techniques to target executive, language, or semantic functions. Thirty-five pertinent studies were identified from January 1990 to August 2016. Functional correlates of TD included the superior and middle temporal, fusiform, and inferior frontal gyri bilaterally, as well as the left and right cingulate cortex, the right caudate nucleus, and the cerebellum. TD-related increases and decreases in activation were both evident in most of these regions. However, the specificity of these correlates from general clinical and cognitive influences is unknown. The cortical regions implicated overlap with those thought to contribute to language and semantic systems. Cortico-striatal circuitry may also play a role in some aspects of TD through aberrant salience representation and inappropriate attentional prioritisation. To advance the field further, greater integration across structural, functional, and behavioural measures is required, in addition to non-unitary considerations of TD.

Imaging and Genetic Biomarkers Predicting Transition to Psychosis

The search for diagnostic and prognostic biomarkers in schizophrenia care and treatment is the focus of many within the research community. Longitudinal cohorts of patients presenting at elevated genetic and clinical risk have provided a wealth of data that has informed our understanding of the development of schizophrenia and related psychotic disorders.Imaging follow-up of high-risk cohorts has demonstrated changes in cerebral grey matter of those that eventually transition to schizophrenia that predate the onset of symptoms and evolve over the course of illness. Longitudinal follow-up studies demonstrate that observed grey matter changes can be employed to differentiate those who will transition to schizophrenia from those who will not prior to the onset of the disorder.In recent years our understanding of the genetic makeup of schizophrenia has advanced significantly. The development of modern analysis techniques offers researchers the ability to objectively quantify genetic risk; these have been successfully applied within a high-risk paradigm to assist in differentiating between high-risk individuals who will subsequently become unwell and those who will not.This chapter will discuss the application of imaging and genetic biomarkers within high-risk groups to predict future transition to schizophrenia and related psychotic disorders. We aim to provide an overview of current approaches focussing on grey matter changes that are predictive of future transition to illness, the developing field of genetic risk scores and other methods being developed to aid clinicians in diagnosis and prognosis.

The efficacy of cerebellar vermal deep high frequency (theta range) repetitive transcranial magnetic stimulation (rTMS) in schizophrenia: A randomized rater blind-sham controlled study

Repetitive transcranial magnetic stimulation (rTMS) is a promising therapeutic for schizophrenia. Treatment effects of rTMS have been variable across different symptom clusters, with negative symptoms showing better response, followed by auditory hallucinations. Cerebellum, especially vermis and its abnormalities (both structural and functional) have been implicated in cognitive, affective and positive symptoms of schizophrenia. rTMS to this alternate site has been suggested as a novel target for treating patients with this disorder. Hypothesizing cerebellar vermal magnetic stimulation as an adjunct to treat schizophrenia psychopathology, we conducted a double blind randomized sham controlled rTMS study. In this study, forty patients were randomly allocated (using block randomization method) to active high frequency (theta patterned) rTMS (n=20) and sham (n=20) groups. They received 10 sessions over 2 weeks. The Positive and Negative Syndrome Scale (PANSS) and Calgary Depression Scale for Schizophrenia (CDSS) scores were assessed at baseline, after last session and at 4 weeks (2 weeks post-rTMS). We found a significantly greater improvement in the group receiving active rTMS sessions, compared to the sham group on negative symptoms, and depressive symptoms. We conclude that cerebellar stimulation can be used as an effective adjunct to treat negative and affective symptoms.

A magnetic resonance imaging study of adhesio interthalamica in clinical subtypes of schizophrenia

CONTEXT

Previous studies have suggested subtle anatomical brain differences between patients with schizophrenia and healthy control subjects. However, the results are inconsistent and there is no study investigating the various subtypes of this mental disorder separately.

AIM

This study was conducted to compare the rate of absence of adhesio interthalamica (AI), a midline brain structure, between 3 subtypes of schizophrenia (paranoid, undifferentiated, and residual) and healthy control group, using magnetic resonance imaging (MRI).

MATERIALS AND METHODS

A total of 29 schizophrenia patients (21 men, 8 women) of three subtypes (paranoid, undifferentiated, and residual) were compared with 29 age- and gender-matched healthy controls. All subjects underwent 3-D brain MRI of full coronal series, 1.5-mm slices without interslice gaps. If the grey matter band connecting the thalami could not be identified on two or more coronal adjacent slices, the AI was considered as absent. The results were statistically analyzed.

RESULTS

The incidence rate of AI absence in patients with heterogenous subtypes of schizophrenia was was similar to control group, even when patients and controls of each gender were compared separately (P>0.05). In residual subtype, patients showed a significant priority in AI absence in comparison with the control group (P=0.041), which was not seen in paranoid and undifferentiated subtypes (P>0.05).

CONCLUSION

Residual subtype of schizophrenia is associated with higher rate of AI absence in this study. Subsequent studies are required to determine if the absence of AI is a cause of residual schizophrenia or an effect.

Absence and size of massa intermedia in patients with schizophrenia and bipolar disorder

OBJECTIVE

To evaluate the absence and size of massa intermedia (MI), a midline thalamic structure, and its gender-specific alteration in patients with schizophrenia and bipolar disorder.

METHODS

Thirty-five patients with schizophrenia (17 females and 18 males), 21 patients with bipolar disorder (15 females and 6 males) and 89 healthy controls (50 females and 39 males) were evaluated by magnetic resonance imaging. Thin-slice magnetic resonance images of the brain were evaluated. MI was determined in coronal and sagittal images, and area of the MI was measured on the sagittal plane.

RESULTS

Females had a significantly lower incidence of absent MI compared with males in the healthy control group. The absence of MI in schizophrenia and bipolar patients was not higher than the incidence in healthy controls. The size of MI showed a gender difference. The mean MI area size was smaller in female schizophrenia patients than in female controls, while no significant difference was observed between male schizophrenia patients and their controls.

CONCLUSIONS

The size of MI, a gender difference midline structure, is smaller in females with schizophrenia, and the results of this study support other studies of structural aberration of the thalamus and other midline structures in the brains of patients with schizophrenia.

The role of the cerebellum in the pathophysiology and treatment of neuropsychiatric disorders: a review

The cerebellum has traditionally been looked upon as a brain area primarily involved in motor behaviour. The last decade has however heralded the cerebellum as a brain region of renewed interest for neuropsychiatric disorders. This renewed interest is fuelled by new insights obtained from neuroanatomical research, modern functional neuroimaging and transcranial magnetic stimulation studies. In this review, evidence in support of cerebellar involvement in neuropsychiatric disorders will be presented. In addition, transcranial magnetic stimulation will be introduced as a novel way to study cerebellar contributions to the pathophysiology of psychiatric disorders. In conclusion, a new functional concept of the cerebellum as more than simply a brain area regulating motor control appears mandatory and the involvement of the cerebellum should be considered when studying the neurological basis of neuropsychiatric disorders.

Reversal of the expression pattern of Aldolase C mRNA in Purkinje cells and Ube 1x mRNA in Golgi cells by a dopamine D1 receptor agonist injections in the methamphetamine sensitized-rat cerebellum

The cerebellum has a parasagittal modular structure, in which Zebrin (Aldolase) positive and negative bands expressed in Purkinje cell layers alternate, and is involved in amphetamine psychosis. Administration of SKF38393, a D1 receptor agonist, reversed the behavioral sensitization of methamphetamine. In the vermis, there were the binding sites of SKF38393. In methamphetamine-sensitized rats the expression of the Aldolase mRNA positive bands move laterally in the rat vermis. We provide here the evidence that the D1 agonist injections also reversed the expression pattern of both the Aldolase mRNA in Purkinje cells and Ube (ubiquitin activating enzyme) 1x mRNA in Golgi interneurons of the sensitized rats. Thus the reverse changes in gene expression pattern in the vermis may be involved in the mechanisms of the behavioral plasticity and suggests the new treatment of drug abuse.

Reduced cerebellar volume and neurological soft signs in first-episode schizophrenia

Recent studies indicate that morphological and functional abnormalities of the cerebellum are associated with schizophrenia. Since the cerebellum is crucial for motor coordination, one may ask whether the respective changes are associated with motor dysfunction in the disease. To test these hypotheses in a clinical study, we investigated cerebellar volumes derived from volumetric magnetic resonance imaging of 37 first-episode patients with schizophrenia, schizophreniform or schizoaffective disorder and 18 healthy controls matched for age, gender and handedness. To control for potential interindividual differences in head size, intracranial volume was entered as a covariate. Neurological soft signs (NSS) were examined after remission of acute symptoms. Compared with the controls, patients had significantly smaller cerebellar volumes for both hemispheres. Furthermore, NSS in patients were inversely correlated with tissue volume of the right cerebellar hemisphere partialling for intracranial volume. No associations were detected between cerebellar volumes and psychopathological measures obtained at hospital admission when patients were in the acute psychotic state or after remission, treatment duration until remission, treatment response or prognostic factors, respectively. These findings support the hypothesis of cerebellar involvement in schizophrenia and indicate that the respective changes are associated with NSS.

MRI volumetry of the vermis and the cerebellar hemispheres in men with schizophrenia

An association between cerebellar abnormalities and different manifestations of schizophrenia is increasingly hypothesized, either at the motor (anterior vermis), affective/psychotic (posterior vermis), or cognitive (cerebellar hemispheres) level. However, morphometric and volumetric cerebellar measurements have yielded highly divergent results. The main goal of this study was to use magnetic resonance imaging (MRI) to separately estimate the volumes of the entire vermis, the cerebellar hemispheres and three midsaggital vermian areas among 38 men with schizophrenia and 26 healthy men. Compared with the control group, persons with schizophrenia had significantly smaller volumes of the whole vermis, but not of the cerebellar hemispheres, a difference that approached significance when only the patients without a comorbid diagnosis of alcohol abuse/dependence were considered. Significant anomalies of the posterior vermian areas (lobules VI and VII) were detected in both subgroups of patients, while abnormalities of the anterior vermis (lobules I-V) were observed only among patients with a dual diagnosis of alcoholism. No difference emerged between the groups at the inferior vermian level (lobules VIII-X). Overall, these findings corroborate the hypothesized association between schizophrenia and specific posterior vermian anomalies, which might not necessarily be the consequence of alcohol abuse. However, the suggestion that schizophrenia is related to abnormal volumes of the lateral cerebellum is not supported.

Selective changes in the shapes of parasagittal bands of Aldoc (Zebrin) mRNA in the rat vermis of the cerebellum after repeated methamphetamine injections

In the cerebellum the mossy and climbing projections, which excite Purkinje cells, display a parasagittal and striped organization. These projections also excite Zebrin (aldolase C: Aldoc) parasagittally. To evaluate the possibility that external stimuli can change the organization of the bands of Aldoc mRNA, we compared the effects of repeated methamphetamine administration on the Aldoc mRNA stripes in the four transverse (anterior, central, posterior and nodular) regions of the vermis with the effects on the glutamate transporter EAAT4 (SCL1A 6) mRNA stripes. In the posterior region the injections four times daily increased the fragmentation of the Aldoc mRNA stripes. The presence of a large amount of fragmentation (forty/cerebellum slice), was accompanied with large lateral dislocations of the Aldoc mRNA stripes. In the central and nodular regions, where the size of the stripe areas decreased significantly the stripes were dislocated laterally. The dislocations of the Aldoc mRNA bands did not occur after a single methamphetamine injection and thus repeated injections were necessary to change the distributions of the lateral bands. In contrast, the distributions of the SCL1A 6 mRNA stripes did not change, even though there was mild fragmentation (six/slice) of the SLC1A 6 mRNA stripes in the anterior region and decreases in the numbers (twelve/slice) in the nodular region. We concluded that excess dopamine selectively changes the location of the Aldoc mRNA compartments in the vermis while the SLC1A 6 mRNA stripes could be changed by other inputs and thus the specific transmitter system might change the specific compartment of the cerebellum.

Sex differences in the absence of massa intermedia in patients with schizophrenia versus healthy controls

OBJECTIVE

To evaluate sexual dimorphism and incidence of absent massa intermedia (MI), a midline thalamic structure, in patients with schizophrenia and healthy controls.

METHODS

Thin slice magnetic resonance images of the brain were obtained. The presence of MI was determined by viewing sagittal, coronal, and axial planes.

RESULTS

In healthy controls, females had a significantly lower incidence of absent MI (13.56%) compared with males (32.08%). In patients with schizophrenia, there was a sex by diagnosis interaction. Female patients had significantly higher incidence of absent MI (32.76%) compared with their healthy controls (13.56%), whereas the male patients showed no difference in incidence of absent MI compared with their controls.

CONCLUSION

The MI, a sexually dimorphic midline structure, is more commonly absent in female patients with schizophrenia. These results support the growing literature reporting structural aberration of the thalamus, as well as other midline structures in the brains of patients with schizophrenia.

An MRI study of midbrain morphology in patients with schizophrenia: relationship to psychosis, neuroleptics, and cerebellar neural circuitry

BACKGROUND

The midbrain contains the perikarya of all the dopamine neurons in the human brain. Although other neurochemicals may well be involved, dopamine dysregulation is central in the pathophysiology of psychosis. Despite this, few imaging studies have evaluated the morphology of the midbrain.

METHODS

Using high-resolution magnetic resonance imaging, morphology of three posterior fossa and brain stem structures were measured: midbrain, pons, and medulla. The patient sample consisted of 50 men with schizophrenia, matched by gender and age to 50 healthy control subjects.

RESULTS

Patients had significantly smaller midbrain measures compared with control subjects. There were no differences between groups in measures of pons or medulla. Furthermore, midbrain size was significantly and inversely correlated with positive symptoms and cumulative neuroleptic exposure, but not with negative or disorganized symptoms. After controlling for the effect of cumulative neuroleptic exposure, the relationship between midbrain morphology and positive symptoms remained significant.

CONCLUSIONS

Midbrain morphology of patients with schizophrenia is abnormal, being smaller in patients compared with control subjects. Although this appears to be specifically related to psychotic symptoms, there is also a robust medication effect, with greater exposure to neuroleptics being associated with greater morphologic abnormality. We discuss the role of dopaminergic dysregulation and possible neural circuit involvement.

Reduced volume of the cerebellar vermis in neuroleptic-naive schizophrenia

BACKGROUND

Neuroimaging studies have suggested the possible role of the cerebellum in the pathophysiology of schizophrenia. However, no study has investigated the detailed structures of the cerebellum in patients without a history of neuroleptic medication. The objective of this study is to examine the volume of detailed structures of the cerebellum in neuroleptic-naive schizophrenic patients and to examine the relationship between cerebellar morphology and clinical symptoms.

METHODS

Magnetic resonance imaging scans were acquired from 20 male neuroleptic-naive schizophrenic patients and 20 healthy control subjects. We measured the volumes of the cerebrum, cerebellar hemisphere, cerebellar gray and white matter, and vermis. Symptoms were assessed with the Brief Psychiatric Rating Scale. Total Brief Psychiatric Rating Scale scores and subscale scores were used for analysis.

RESULTS

The volume of the vermis was significantly reduced in the schizophrenic group relative to the control group, whereas no significant differences were found in the volumes of other cerebellar structures and the cerebrum. Reduction in the vermal volume correlated with the total Brief Psychiatric Rating Scale Depression subscore and Paranoia subscore.

CONCLUSIONS

This study indicates that the volume of the vermis is reduced in patients with schizophrenia, and reduction in vermal volume is suggested to be related to the pathophysiology of the disease.

Cerebellar vermis area in schizophrenic patients - a post-mortem study

Neuroimaging studies of cerebellar atrophy in schizophrenia have yielded contradictory results. In computer-tomography (CT) studies, cerebellar atrophy was found in up to 40% of schizophrenic patients. However, several recent magnetic resonance imaging (MRI) studies could not replicate these early findings; in addition, contradictory observations of enlargement of vermal structures were reported. In contrast to the number of CT and MRI studies, there are only a few neuropathological reports on this subject. In a post-mortem study we analyzed the midsagittal vermal area of formaldehyde-fixed cerebella of 12 deceased schizophrenic patients and 12 age- and gender-matched control subjects by using morphometrical methods. Statistical analysis using ANOVA revealed no significant group effects, but there were interactions with gender and cerebellar brain weight. In view of the present results, the common concept of cerebellar atrophy in schizophrenic patients appears premature. Gender effects and secondary processes (e.g., relevant alcohol or drug abuse) cannot be excluded as possible factors causing decrease of vermal areas in schizophrenic patients.

An MRI study of cerebellar vermis morphology in patients with schizophrenia: evidence in support of the cognitive dysmetria concept

BACKGROUND

Cumulative evidence suggests the cerebellum is involved in cognition and may be important in the pathoetiology of schizophrenia. Functional imaging studies have identified a possible neural circuit that includes the cerebellum and may be abnormal in patients with schizophrenia, manifesting as a fundamental cognitive deficit conceptualized as cognitive dysmetria. To explore the role of the cerebellum in cognitive dysfunction and schizophrenia, this study was designed to evaluate the morphology of the cerebellar vermis, its relationship to other cortical areas, and to cognitive function in patients with schizophrenia.

METHODS

Male patients with schizophrenia (n = 65) were matched by age and gender to 65 healthy male controls. Volume measures of the 4 cerebral lobes and total cerebellum were obtained using automated methods. The area of the cerebellar vermis (divided into three lobes) was traced on a midsaggital MRI slice.

RESULTS

Patients had smaller frontal and temporal lobes. There were no group differences in total cerebellar volume. Patients had a smaller vermis area, accounted for by a smaller anterior lobe. The anterior vermis area was positively correlated with total cerebellar volume, temporal lobe volume, and FSIQ in patients, but not controls.

CONCLUSIONS

These findings support the theory that regions of the cerebellum may be involved in a neural circuit that is structurally and functionally abnormal in patients with schizophrenia, leading to cognitive dysmetria.

Differences in cerebellar blood volume in schizophrenia and bipolar disorder

Brain morphometry has been studied extensively in schizophrenic patients, and among the cortical differences identified two consistent findings are decreased cerebellar vermal volume and increased volume of the fourth ventricle; although contradictory findings are reported as well. Recent cognitive activation studies utilizing PET, SPECT and fMRI have identified both decreased and increased activation in the cerebellum of schizophrenic patients compared with healthy controls. This study used DSC fMRI to map cerebellar blood volume in patients with schizophrenia or bipolar disorder and healthy controls. For all cerebellar regions analyzed, schizophrenic patients had the highest cerebellar blood volume, while bipolars had the lowest blood volume. Morphometric measurements were completed and indicated that the ratio of vermis to whole CBL tissue volume was 24% less for the schizophrenic population than controls, whereas the subjects with bipolar disorder had a ratio that was non-significantly smaller than controls by 19%. Comparison of morphometric data with blood volume data did not reveal any statistically significant correlations among the study groups.

Recalling word lists reveals "cognitive dysmetria" in schizophrenia: a positron emission tomography study

OBJECTIVE

This study explored the neural circuitry used during recall of unstructured verbal material in schizophrenic patients and healthy volunteer subjects.

METHOD

The subjects were 13 healthy volunteers and 14 schizophrenic patients. All patients were free of medication, and all subjects were right-handed. Two experimental cognitive conditions were used: recall of novel and practiced word lists (two 15-item lists from the Rey Auditory Verbal Learning Test). Both active recall tasks were compared with an eyes-closed resting baseline condition. A nonparametric randomization test was used to determine within- and between-group differences in regional cerebral blood flow.

RESULTS

Performance on both the practiced and novel memory tasks was nonsignificantly different in the patients and control subjects. During the novel memory task, the patients showed decreased flow in the right anterior cingulate, right thalamus, and bilateral cerebellum (left greater than right) relative to the control subjects. When recalling the practiced word lists, the patients showed decreased flow in the left dorsolateral prefrontal cortex, bilateral medial frontal cortex, left supplementary motor area, left thalamus, left cerebellar regions, anterior vermis, and right cuneus.

CONCLUSIONS

Patients with schizophrenia fail to activate cortical-cerebellar-thalamic-cortical circuitry during recall of both well-learned and novel word lists.

Active and remitted schizophrenia: psychopathological and regional cerebral blood flow findings

Single photon emission computed tomography with technetium-99m-d,l-hexamethylpropyleneamine oxime (99mTc-HMPAO) was used to assess regional cerebral blood flow (rCBF) during both florid and remitted stages of schizophrenia. Forty schizophrenic patients in an active phase of illness (diagnosis by DSM-III-R) were examined in two clinical states (ill vs. improved). At study entry, 24 patients were drug-naive, five were currently drug-free, and 11 were being treated with antipsychotic medication. Twenty medical patients who suffered from non-specific headaches but were free of neurological and psychiatric symptoms served as control subjects. At initial examination during the active phase of illness, cerebral perfusion patterns in the schizophrenic patients were characterized by both hypofrontality and hypotemporality. After remission, hypofrontality was no longer apparent in two of four frontal regions, and hypotemporality disappeared completely. As assessed with the Positive and Negative Syndrome Scale (PANSS), formal thought disorders, hallucinations, and ideas of grandiosity correlated with rCBF in the active phase of illness, but not after remission. In the remitted but not in the florid state, blunted affect, difficulties in abstract thinking, lack of spontaneity, and stereotyped thoughts correlated with rCBF. Correlations of five symptoms with rCBF changed significantly from first to second examination. The present study suggests that correlations between single psychotic symptoms and rCBF differ significantly in florid vs. remitted phases of schizophrenia.

Differential decreases in c-fos and aldolase C mRNA expression in the rat cerebellum after repeated administration of methamphetamine

The effects of repeated methamphetamine administration on c-fos mRNA and aldolase C (Zebrin) mRNA expression in the rat cerebellum were investigated. A single dose of methamphetamine induced c-fos mRNA expression in granule and Purkinje cells of both anterior and posterior lobes. In the posterior lobe, in particular, c-fos mRNA signals were distributed in a parasagittal organization, like Zebrin bands. Repeated methamphetamine injections reduced methamphetamine-induced c-fos mRNA signals in the anterior hemisphere and in part of the posterior vermis (lobule VII) and posterior hemisphere. Aldolase C mRNA signals in Purkinje cells decreased only in lobules where methamphetamine-induced c-fos signals were not reduced (lobules VI and IX). Therefore, differential decreases in c-fos mRNA and aldolase C mRNA expression after repeated methamphetamine administration depend upon the localization of Purkinje cells in the cerebellum. Since c-fos mRNA and aldolase C mRNA expressions are markers of excitability and the metabolic state of Purkinje cells, respectively, hypofunction of inhibitory Purkinje cells could be induced if methamphetamine is repeatedly injected. Since repeated methamphetamine administration in this experimental paradigm increased horizontal movement and the rearing activity of rats, the hemisphere of the cerebellum may be involved in development of methamphetamine-induced motor behavioral sensitization in addition to the striatum and the nucleus accumbens.

Cerebellar morphology as a predictor of symptom and psychosocial outcome in schizophrenia

BACKGROUND

In this study, we examined whether brain morphology assessed early in the course of schizophrenia predicted psychosocial or symptomatic outcome.

METHODS

We acquired magnetic resonance images on 63 subjects with schizophrenia spectrum disorders and manually traced regions of interest, including the cerebrum, temporal lobes, ventricles, and cerebellum. Subjects were then prospectively assessed every 6 months for an average of 7 years. Outcome symptom measures were longitudinal rather than cross-sectional, and included average number of weeks per year spent in a psychotic negative, or disorganized symptom syndrome, and average number of weeks of inpatient treatment per year. A psychosocial outcome measure summed ratings of impairment in employment, recreation, sexual activity, and interpersonal relationships.

RESULTS

Negative associations were found between cerebellar volume and three outcome measures: negative and psychotic symptom duration, and psychosocial impairment.

CONCLUSIONS

These results underscore the potential role of cerebellar abnormalities in the etiology and pathophysiology of schizophrenia.

Single-voxel proton magnetic resonance spectroscopy of the pons and cerebellum in patients with schizophrenia: a preliminary study

Magnetic resonance spectroscopy (MRS) is a non-invasive functional imaging technique that can measure various brain tissue metabolites such as N-acetylaspartate (NAA), choline (Cho), creatine-phosphocreatine (Cr), myo-inositol (mI) and other metabolites. Morphological studies have indicated the pons and cerebellum as possible sites of abnormal functioning in schizophrenic patients. This study examines schizophrenic patients for the presence of abnormalities in proton MRS (1H-MRS) measured metabolites in two regions of the posterior fossa. Twelve schizophrenic patients and eight non-schizophrenic control subjects were studied by measuring the ratios of NAA/Cr, Cho/Cr and mI/Cr from 1H-spectra obtained from the pons and right or left cerebellum using an integrated MRI/MRS protocol. Spectra were obtained from a voxel in the pons and voxels from the left and/or right lateral cerebellum. Data were analyzed in the absorption mode and fitted to Lorentzian lineshapes using a Marquart algorithm. Significantly lower NAA/Cr ratios were found in the pons of schizophrenic patients than in the control subjects, but not in the cerebellum. This study is the first to measure brain tissue metabolites using 1H-MRS in the pons and cerebellum of schizophrenic patients. Significant alterations of 1H-MRS metabolites may suggest the involvement of the posterior fossa as a part of the pathological substrate underlying schizophrenia.

Cerebral perfusion correlates of negative symptomatology and parkinsonism in a sample of treatment-refractory schizophrenics: an exploratory 99mTc-HMPAO SPET study

There is a well recognized clinical overlap between primary and secondary neuroleptic negative symptoms in schizophrenia, but their cerebral substrates are probably different. The study of these substrates could contribute to a better understanding and management of these syndromes. In the present work, the cerebral perfusion correlates, as an indirect measure of the underlying neuronal function, of negative symptoms and parkinsonism were studied with single-photon emission tomography in a group of treatment-refractory paranoid schizophrenic patients. Perfusion ratios with respect to the homolateral cerebellum were compared with a normal database. Correlation coefficients were calculated between perfusion ratios, negative symptoms and parkinsonism scores on exploratory grounds. As a group, the patients showed a bilateral, but predominantly left-sided, hypofrontality and hypotemporality, as well as an increased perfusion in right basal ganglia. Negative symptoms scores negatively correlated with prefrontal perfusion, while parkinsonism positively correlated with the activity of primary motor and sensory cortex. These findings support the existence of different cerebral substrates for primary and secondary negative symptoms in schizophrenia.

Application of [3H]L-N(G)-nitro-arginine labelling to measure cerebellar nitric oxide synthase in patients with schizophrenia

Brains from patients with schizophrenia have been reported to contain deficient and dysplastic forebrain neurons containing nitric oxide synthase (NOS). As part of a study of NOS in schizophrenia, we decided to investigate the cerebellum, which has particularly high levels of NOS. We used an autoradiographic method to measure the density and distribution of NOS. Sections of frozen cerebellum removed at autopsy were labelled with the selective NOS inhibitor [3H]L-NG-nitro-arginine. NOS levels were visualized in sagittal sections of vermis from 16 control subjects and 21 schizophrenia patients, and measurements were taken from the three groups of developmentally-distinct lobules I-V, VI-VII and VIII-X. The highest NOS density was in the Purkinje/molecular layer of cerebellar cortex, although there was some NOS in the granule cell layer. There were no differences in Purkinje/molecular or granule cell layer NOS levels between the two groups of subjects. The mild structural faults in cerebellar vermis observed in some patients with schizophrenia probably do not involve reductions in NOS-containing cells.

Cerebellar blood flow in schizophrenic patients and normal control subjects

We used 133Xe dynamic single-photon emission computed tomography (DSPECT) to measure the resting cerebellar blood flow in 17 neuroleptic-free schizophrenic and schizophreniform patients and 13 normal control subjects. A subset of these subjects (11 patients and 7 control subjects) additionally underwent activation studies during the Wisconsin Card Sorting (WCS) and Number Matching (NM) tests. Baseline relative cerebellar blood flow was significantly lower in older patients than in age-matched control subjects. For absolute cerebellar flow, there was a significant difference between patients and control subjects in the overall activation response (patients: NM 13.4% increase, WCS 15.7% increase; control subjects: NM 3.1% decrease, WCS 0.0% change). This difference was more pronounced in older subjects. Cerebral blood flow significantly increased during NM (patients: 21.3% increase, control subjects: 6.5% increase) and WCS (patients: 16.5% increase, control subjects: 9.7% increase). The difference in the magnitude of cerebral NM activation between schizophrenic patients and control subjects, although not statistically significant, may call into question the appropriateness of using NM as a control task in schizophrenic patients. Finally, we found no differences between the effects of WCS and NM on cerebellar or cerebral blood flow. Because of the small number of subjects in each group, the results of this study should be interpreted cautiously.

Cerebellar contributions to cognition

This review summarises the present evidence for the contribution of the cerebellum to cognition. While a data base from both animal and human clinical research supports the hypothesis of an important cerebellar role in motor adaptation, motor learning and timing, the evidence for the implication of the cerebellum in psychopathology and non-motor cognitive functions is incomplete and does not allow unequivocal conclusions. Methodological shortcomings and the lack of theoretical models on the nature of the cerebellar contribution to cognition limit the interpretation of the empirical studies available so far.

Psychotic behavior associated with cerebellar pathology

This report concerns a 27-year-old man in whom psychotic behavior emerged in association with a cerebellar tumor. This presentation supports previous clinical observations which postulate an intimate relationship between cerebellar pathology and the development of schizophrenia.