Chronic mania in childhood: case report of a possible association with a radiological picture of cerebellar disease

Aberrant cerebellar connectivity in bipolar disorder with psychosis

BACKGROUND

The cerebellum, which modulates affect and cognition in addition to motor functions, may contribute substantially to the pathophysiology of mood and psychotic disorders, such as bipolar disorder. A growing literature points to cerebellar abnormalities in bipolar disorder. However, no studies have investigated the topographic representations of resting state cerebellar networks in bipolar disorder, specifically their functional connectivity to cerebral cortical networks.

METHODS

Using a well-defined cerebral cortical parcellation scheme as functional connectivity seeds, we compared ten cerebellar resting state networks in 49 patients with bipolar disorder and a lifetime history of psychotic features and 55 healthy control participants matched for age, sex, and image signal-to-noise ratio.

RESULTS

Patients with psychotic bipolar disorder showed reduced cerebro-cerebellar functional connectivity in somatomotor A, ventral attention, salience, and frontoparietal control A and B networks relative to healthy control participants. These findings were not significantly correlated with current symptoms.

CONCLUSIONS

Patients with psychotic bipolar disorder showed evidence of cerebro-cerebellar dysconnectivity in selective networks. These disease-related changes were substantial and not explained by medication exposure or substance use. Therefore, they may be mechanistically relevant to the underlying susceptibility to mood dysregulation and psychosis. Cerebellar mechanisms deserve further exploration in psychiatric conditions, and this study's findings may have value in guiding future studies on pathophysiology and treatment of mood and psychotic disorders, in particular.

Dysmetria of thought: clinical consequences of cerebellar dysfunction on cognition and affect

Cognitive and emotional changes might be prominent or even principal manifestations of cerebellar lesions. This realization supports evidence suggesting that the cerebellum is an important part of a set of distributed neural circuits that subserve higher-order processing. Early anecdotal clinical accounts described aberrant mental or intellectual functions in the setting of cerebellar atrophy. Later systematic analyses showed that the cerebellum is able to influence autonomic, vasomotor, and emotional behaviors, and further studies revealed neuropsychological deficits in patients with degenerative diseases. Current descriptions of behavioral changes in adults and children with acquired cerebellar lesions bring the debate about the cerebellar role in neural function within the realm of clinically relevant cognitive neuroscience. The activation of focal cerebellar regions by cognitive tasks on functional neuroimaging studies, and morphologic abnormalities of cerebellum in psychiatric diseases such as autism and schizophrenia further support this view. Anatomical substrates have been elucidated that could support a cerebellar role in cognition and emotion. Our concept of `dysmetria of thought' draws an analogy with the motor system to describe and explain the impairments of higher-order behavior that result when the distributed neural circuits subserving cognitive operations are deprived of cerebellar modulation.

Postural control in bipolar disorder: increased sway area and decreased dynamical complexity

Structural, neurochemical, and functional abnormalities have been identified in the brains of individuals with bipolar disorder, including in key brain structures implicated in postural control, i.e. the cerebellum, brainstem, and basal ganglia. Given these findings, we tested the hypothesis that postural control deficits are present in individuals with bipolar disorder. Sixteen participants with bipolar disorder (BD) and 16 age-matched non-psychiatric healthy controls were asked to stand as still as possible on a force platform for 2 minutes under 4 conditions: (1) eyes open-open base; (2) eyes closed-open base; (3) eyes open-closed base; and (4) eyes closed-closed base. Postural sway data were submitted to conventional quantitative analyses of the magnitude of sway area using the center of pressure measurement. In addition, data were submitted to detrended fluctuation analysis, a nonlinear dynamical systems analytic technique that measures complexity of a time-series, on both the anterior-posterior and medio-lateral directions. The bipolar disorder group had increased sway area, indicative of reduced postural control. Decreased complexity in the medio-lateral direction was also observed for the bipolar disorder group, suggesting both a reduction in dynamic range available to them for postural control, and that their postural corrections were primarily dominated by longer time-scales. On both of these measures, significant interactions between diagnostic group and visual condition were also observed, suggesting that the BD participants were impaired in their ability to make corrections to their sway pattern when no visual information was available. Greater sway magnitude and reduced complexity suggest that individuals with bipolar disorder have deficits in sensorimotor integration and a reduced range of timescales available on which to make postural corrections.

Paced finger-tapping abnormalities in bipolar disorder indicate timing dysfunction

OBJECTIVES

Theoretical and empirical evidence suggests that impaired time perception and the neural circuitry contributing to internal timing mechanisms may contribute to severe psychiatric disorders, including mood disorders. The structures that are involved in subsecond timing, i.e., cerebellum and basal ganglia, have also been implicated in the pathophysiology of bipolar disorder. However, the timing of subsecond intervals has infrequently been studied in this population.

METHODS

Paced finger-tapping tasks have been used to characterize internal timing processes in neuropsychiatric disorders. A total of 42 bipolar disorder patients (25 euthymic, 17 manic) and 42 age-matched healthy controls completed a finger-tapping task in which they tapped in time with a paced (500-ms intertap interval) auditory stimulus (synchronization), then continued tapping without auditory input while attempting to maintain the same pace (continuation). This procedure was followed using the dominant index finger, then with alternating thumbs.

RESULTS

Bipolar disorder participants showed greater timing variability relative to controls regardless of pacing stimulus (synchronization versus continuation) or condition (dominant index finger versus alternating thumbs). Decomposition of timing variance into internal clock versus motor implementation components using the Wing-Kristofferson model showed higher clock variability in the bipolar disorder groups compared to controls, with no differences between groups on motor implementation variability.

CONCLUSIONS

These findings suggest that internal timing mechanisms are disrupted in bipolar disorder patients, independent of symptom status. Increased clock variability in bipolar disorder may be related to abnormalities in cerebellar function.

Eyeblink conditioning anomalies in bipolar disorder suggest cerebellar dysfunction

OBJECTIVES

Accumulating research implicates the cerebellum in non-motor psychological processes and psychiatric diseases, including bipolar disorder (BD). Despite recent evidence that cerebellar lesions have been documented to trigger bipolar-like symptoms, few studies have directly examined the functional integrity of the cerebellum in those afflicted with BD.

METHODS

Using a single-cue delay eyeblink conditioning procedure, the functional integrity of the cerebellum was examined in 28 individuals with BD (9 manic, 8 mixed, and 11 euthymic) and 28 age-matched healthy controls.

RESULTS

Analysis of the bipolar group as a whole indicated a conditioned response acquisition and timing deficit compared to controls. However, when the bipolar group was categorized according to mood state (mixed, manic, euthymic), individuals tested during mixed episodes were strikingly impaired, performing significantly worse than all other groups on both the acquisition and timing of conditioned responses.

CONCLUSIONS

These findings extend prior research implicating cerebellar functional abnormalities in BD and suggest that cerebellar dysfunction may be associated with mood state and course of illness.

Rational approaches to the neurobiologic study of youth at risk for bipolar disorder and suicide

OBJECTIVES

The aims of this paper are to provide an overview of neuroimaging findings specific to bipolar disorder and suicide, and to consider rational approaches to the design of future in vivo studies in youth at risk.

METHODS

Neuroimaging and related neurobiological literature pertaining to bipolar disorder and suicide in adult and pediatric samples was reviewed in a non-quantitative manner.

RESULTS

Specific structural and functional brain findings in bipolar disorder are described, where possible in the context of relevant current neurobiological theories of etiology. Diagnostic and prognostic implications are discussed.

CONCLUSIONS

The simultaneous use of complementary neurobiological approaches may be a powerful way of identifying and validating factors reliably associated with bipolar disorder and suicide. A profile of neurobiological markers with which to screen for bipolar disorder and suicide risk may provide for earlier and more accurate diagnosis, perhaps even in the pre- or subsyndromal stages in high-risk youth.

Effects of mood and subtype on cerebral glucose metabolism in treatment-resistant bipolar disorder

BACKGROUND

Functional brain imaging studies in unipolar and secondary depression have generally found decreased prefrontal cortical activity, but in bipolar disorders findings have been more variable.

METHODS

Forty-three medication-free, treatment-resistant, predominantly rapid-cycling bipolar disorder patients and 43 age- and gender-matched healthy control subjects had cerebral glucose metabolism assessed using positron emission tomography and fluorine-18-deoxyglucose.

RESULTS

Depressed bipolar disorder patients compared to control subjects had decreased global, absolute prefrontal and anterior paralimbic cortical, and increased normalized subcortical (ventral striatum, thalamus, right amygdala) metabolism. Degree of depression correlated negatively with absolute prefrontal and paralimbic cortical, and positively with normalized anterior paralimbic subcortical metabolism. Increased normalized cerebello-posterior cortical metabolism was seen in all patient subgroups compared to control subjects, independent of mood state, disorder subtype, or cycle frequency.

CONCLUSIONS

In bipolar depression, we observed a pattern of prefrontal hypometabolism, consistent with observations in primary unipolar and secondary depression, suggesting this is part of a common neural substrate for depression independent of etiology. In contrast, the cerebello-posterior cortical normalized hypermetabolism seen in all bipolar subgroups (including euthymic) suggests a possible congenital or acquired trait abnormality. The degree to which these findings in treatment-resistant, predominantly rapid-cycling patients pertain to community samples remains to be established.

Rediscovery of an early concept

The study of the cerebellum has been dominated by interest in its role in movement and motor control. From the earliest days of the neuroscientific era, however, clinical reports and physiological and behavioral investigations have suggested that overt motor dysfunction is but one manifestation of cerebellar disease. The nature of cerebellar involvement in autonomic, sensory, and cognitive functions has been investigated for many years, and possible mechanisms that could subserve this relationship have been specifically addressed. This work has not been incorporated into the mainstream of neuroscience or clinical neurological thinking. This chapter traces the history of these early investigations that demonstrated the need to revise the notion that cerebellar function is confined to the motor realm. The collaboration across disciplines and the advances in the methods and concepts of contemporary neuroscience have facilitated the maturation of this field of inquiry. The "new" story of the cerebellum and cognition, in fact, represents the evolution of a century-old revolutionary concept.

Neuropsychological abnormalities in cerebellar syndromes--fact or fiction?

In recent years, theoretical considerations and a large number of empirical investigations have been published in support of a cerebellar involvement in cognitive processing. This chapter aims at a critical evaluation of the neuropsychological findings from clinical studies of patients with cerebellar syndromes. The discussion will mainly consider data from patients with selective cerebellar dysfunction, as data from patients with combined cerebellar and extracerebellar damage are of limited value for the issue of a cerebellar involvement in cognition. Early clinical observations indicated that degenerative diseases or selective cerebellar lesions did not necessarily give rise to general intellectual impairment such as dementia. Recent neuropsychological evidence based on standardized testing does not yet provide a clear picture. Deficits in motor learning or temporal processing are consistently observed in patients with cerebellar syndromes, while the cerebellum does not appear to be critically involved in general intellectual capacities or memory. Deficits in frontal lobe function, visuospatial processing or nonmotor skill learning have been reported in several studies, but have not been replicated in others. Such discrepancies may relate to a number of methodological problems. Future neuropsychological studies should take such methodological issues into account by using patients with selective cerebellar dysfunction, adequately matched clinical and non-clinical comparison groups, and theory-driven iesl batteries comprising a wide range of tests.

Bipolar disorders, dystonia, and compulsion after dysfunction of the cerebellum, dentatorubrothalamic tract, and substantia nigra

Bipolar disorders occurred in 3 of 15 (20%) subjects after focal cerebellar circuit lesions. Two presented with rapid cycling bipolar disorder and dystonia, including one with a checking compulsion. Lesions included right cerebellar hypoplasia (bipolar disorder), bilateral cerebellar atrophy (rapid cycling unipolar mania and dystonia), and left midbrain pathology (mixed bipolar disorder, dystonia, and compulsion). Bipolar disorders were associated with cerebellar circuit pathology (p = 0.032) and were more prevalent than in population controls (p = 0.004). Diminished cerebellar output (to cortical, thalamic, basal ganglia, limbic, or other circuits) or nigral pars reticulata dysfunction may result in abnormal neuronal oscillation in bipolar disorders, especially rapid-cycling types, or in dystonia. Review of the literature supports the concept of nigral and cerebellar direct and indirect connections with thalamofrontotemporal and basal ganglia circuits in bipolar disorders, dystonia, and compulsions, as well as possible clinical relationships between these disorders.

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.

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

Degeneration of the cerebellar vermis is a common pathological and neuroradiological feature of chronic schizophrenia, but its relationship to symptoms of the disease are poorly understood. We investigated the relationship of vermal cerebellar atrophy on CT scan to features of positive (productive) and negative (defect) dimensions of schizophrenia as well as to symptoms of general psychopathology in a sample of 23 chronic schizophrenic patients. For comparison, we also studied the relationship of third ventricular width (TVW), which reflects periventricular and diencephalic atrophy, to these features of schizophrenic symptomatology. Vermal cerebellar atrophy was found in 43.5% of patients and correlated significantly with general psychopathology and, more specifically, with feelings of guilt and disturbance of volition. It was unrelated to global positive or negative features of schizophrenia. By contrast, TVW was uniquely associated with global negative syndrome. These observations indicate that degeneration of the cerebellar vermis and enlargement of the third ventricle are integral aspects of schizophrenia, and that each contributes independently to specific clinical aspects of the disease.

Childhood and adolescent depression. II: Research in clinical populations

The tremendous increase in interest in childhood and adolescent depression that has occurred since the early 1970s has resulted in a large and contradictory literature. Development of the concept of childhood depression, and the many clinical studies of depression and its concomitants, both psychosocial and biological, are critically reviewed. A number of methodological and theoretical problems are discussed.

Cerebellar pathology in schizophrenia--cause or consequence?

Atrophy of the cerebellar vermal cortex has been reported to occur in 10% or more of patients with schizophrenia. Data from studies on experimental animals indicate that a functional relationship between the cerebellum and parts of the forebrain involved in emotion exists, and that the cerebellum may influence some types of behavior. Cerebellar abnormality in schizophrenic patients, although of uncertain cause, could contribute to the symptomatology of the disease.