Tardive dyskinesia with inflated neurons of the cerebellar dentate nucleus. Case reports and morphometric study

Copy number variant syndromes are frequent in schizophrenia: Progressing towards a CNV-schizophrenia model

The genetic underpinnings of schizophrenia (SCZ) remain unclear. SCZ genetic studies thus far have only identified numerous single nucleotide polymorphisms with small effect sizes and a handful of copy number variants (CNVs). This study investigates the prevalence of well-characterized CNV syndromes and candidate CNVs within a cohort of 348 SCZ patients, and explores correlations to their phenotypic findings. There was an enrichment of syndromic CNVs in the cohort, as well as brain-related and immune pathway genes within the detected CNVs. SCZ patients with brain-related CNVs had increased CNV burden, neurodevelopmental features, and types of hallucinations. Based on these results, we propose a CNV-SCZ model wherein specific phenotypic profiles should be prioritized for CNV screening within the SCZ patient population.

Focus on lower risk of tardive dyskinesia with atypical antipsychotics

BACKGROUND

Tardive dyskinesia (TD) is one of the most serious iatrogenic neurological complications of the first-generation antipsychotics. Identifying the risk factors for TD is important to minimize the risk of this potentially irreversible movement disorder in susceptible populations.

METHODS

A Medline search was conducted for the literature on risk factors for TD with the first-generation antipsychotics, as well as the emerging literature of the lower risk of TD with the second-generation antipsychotics.

RESULTS

Several demographic, phenomenological, comorbidities and treatment variables have been reported to be associated with higher risk of TD. On the other hand, significantly lower rates of TD have been reported with the second-generation atypical antipsychotics, even in high risk groups such as the elderly.

CONCLUSIONS

The use of the second-generation antipsychotics as first-line treatment of psychosis appears to have lowered the overall prevalence of acute movement disorders as well as TD, and have led them to become the standard of care in part because of their safer extrapyramidal profiles.

Sigma receptors: recent advances and new clinical potentials

Several recent advances are leading to a better understanding of sigma receptors. Here we focus on our recent findings regarding cellular functions of sigma-2 receptors and discuss their possible clinical implications. Agonists at sigma-2 receptors induced changes in cell morphology and apoptosis in various cell types. Sigma-2 receptor activation produced both transient and sustained increases in [Ca++]i, derived from different intracellular stores. These changes in [Ca++]i and cytotoxic effects are mediated by intracellular sigma-2 receptors. Sigma-2 agonists induced apoptosis in drug-resistant cancer cells, enhanced the potency of DNA damaging agents, and down-regulated expression of p-glycoprotein mRNA. Thus, sigma-2 receptor agonists may be useful in treatment of drug-resistant cancers. Sigma radioligands have been used in tumor imaging. We also discuss how sigma-2 antagonists might prevent the irreversible motor side effects of typical neuroleptics. Sigma-2 receptors may subserve a novel signalling pathway to apoptosis, involved in regulation of cell proliferation and/or viability.

Tardive dyskinesia in a chronically institutionalized population of elderly schizophrenic patients: prevalence and association with cognitive impairment

BACKGROUND

Chronically hospitalized geriatric inpatients with schizophrenia are at particular risk for both tardive dyskinesia (TD) and cognitive impairment but have been insufficiently studied in this regard. Similarly, the relationship between TD and cognitive impairment has not be adequately addressed in this population.

OBJECTIVES

(1) To determine the prevalence of TD in a cohort of chronically institutionalized schizophrenic geriatric inpatients. (2) To examine the relationship between the manifestations of TD in various body regions and several potentially related variables including current pharmacological regimen, age, age at first hospitalization and cognitive status.

METHOD

TD was assessed by the Modified Simpson Dyskinesia Scale and cognitive status by the Mini-Mental State Examination (MMSE). The relationship between manifestations of TD and other variables was examined by t-tests, ANOVA, MANOVA and correlational analysis.

RESULTS

The prevalence of TD was 60%. Prevalence increased with age but was not related to current antipsychotic or anticholinergic regimen. Mean MMSE score did not differ between groups of patients with and without TD as defined by the criteria of Schooler and Kane (1982); however, the mean MMSE score was significantly (p < 0.0004) lower in subjects with orofacial TD as defined by Waddington and Youssef (1996), and the difference was not entirely accounted for by the older age of the latter group.

CONCLUSIONS

TD and cognitive impairment both increase with age. However, TD alone does not account for the severity of cognitive impairment in this population. The present study provides further support for the hypothesis that the correlation between TD and cognitive impairment holds primarily for the orofacial manifestations of TD.

Effects of haloperidol and reduced haloperidol on binding to sigma sites

The s.c. administration of a single dose of 0.1 mg/kg of reduced haloperidol to guinea pigs produced a marked inhibition of the binding of [3H]dextromethorphan and [3H]3-(3-hydroxyphenyl)-N-(n-propyl)piperidine ([3H](+)-3-PPP) to brain. The inhibition was still evident 10 days later, and it was accompanied by residual brain levels of reduced haloperidol, and much lower levels of haloperidol. Scatchard and computer-assisted analysis demonstrated that the inhibition was due to a reduction in the number of binding sites without changes in the affinity. In the rat, haloperidol and reduced haloperidol also produced a rapid inhibition of binding to sigma sites. Interestingly, the brain of the reduced haloperidol-treated rats contained both haloperidol and reduced haloperidol, but the levels of reduced haloperidol in the haloperidol-treated rats were undetectable. However, the inhibition observed was of comparable magnitude, indicating that the haloperidol remaining in the brain is also inhibitory. In vitro experiments showed that the inhibition produced by haloperidol and reduced haloperidol was apparently competitive, but when brain membranes were preincubated with either drug, the inhibition was noncompetitive. By contrast, the inhibition produced by dextromethorphan was always competitive. Moreover, the inhibition produced by haloperidol and reduced haloperidol could not be reversed by washing. This investigation strongly suggests that the inhibition observed after the administration of haloperidol or reduced haloperidol is not a classic agonist-induced receptor down-regulation. The results indicated that the inhibition produced is a complex phenomenon, and suggest the formation of a slowly reversible or irreversible complex with reduced haloperidol or haloperidol.

Brain iron homeostasis

The anatomical and cellular distribution of non-haem iron, ferritin, transferrin, and the transferrin receptor have been studied in postmortem human brain and these studies, together with data on the uptake and transport of labeled iron, by the rat brain, have been used to elucidate the role of iron and other metal ions in certain neurological disorders. High levels of non-haem iron, mainly in the form of ferritin, are found in the extrapyramidal system, associated predominantly with glial cells. In contrast to non-haem iron, the density of transferrin receptors is highest in cortical and brainstem structures and appears to relate to the iron requirement of neurones for mitochondrial respiratory activity. Transferrin is synthesized within the brain by oligodendrocytes and the choroid plexus, and is present in neurones, consistent with receptor mediated uptake. The uptake of iron into the brain appears to be by a two-stage process involving initial deposition of iron in the brain capillary endothelium by serum transferrin, and subsequent transfer of iron to brain-derived transferrin and transport within the brain to sites with a high transferrin receptor density. A second, as yet unidentified mechanism, may be involved in the transfer of iron from neurones possessing transferrin receptors to sites of storage in glial cells in the extrapyramidal system. The distribution of iron and the transferrin receptor may be of relevance to iron-induced free radical formation and selective neuronal vulnerability in neurodegenerative disorders.

Tardive dyskinesia in Alzheimer's disease: clinical features and neuropathologic correlates

Medical record review was conducted on 14 patients with neuropathologically confirmed Alzheimer's disease, all of whom had been treated with antipsychotic medications, to determine the relationship between neuropathology and the development of tardive dyskinesia. Four cases were found to have chart descriptions of hyperkinetic movement disorders consistent with tardive dyskinesia. When the group with tardive dyskinesia was compared to the group without tardive dyskinesia, there were no statistically significant differences regarding gender, age of onset of dementia, duration of dementia, age at death, or duration of antipsychotic treatment. Neuropathologic comparisons revealed greater degenerative changes in the substantia nigra in those patients with tardive dyskinesia. These preliminary observations suggest that patients with Alzheimer's disease and significant coexisting substantia nigra pathologic changes may be at higher risk for developing tardive dyskinesia when treated with antipsychotic medication.

Neuropathology in movement disorders

This review concentrates on the definition and classification of degenerative movement disorders in which Parkinsonian symptoms are often prominent. The pathological spectrum and clinical manifestations of Lewy body disease are described, and associations with Alzheimer's disease and motor neuron disease are explored. A classification of pallidonigral degenerations is based on clinical features, distribution of pathology, and morphological abnormalities; some of these patients have mild nigral degeneration and no Parkinsonian features. Many other juvenile and familial Parkinsonian cases are not included among the pallidonigral degenerations. Most of these latter syndromes have been organised into preliminary groups, in particular, autosomal dominant dystonia-Parkinson syndrome, juvenile Parkinsonian disorder and autosomal dominant Lewy body disease.

"Grumose degeneration" of the dentate nucleus. A light and electron microscopic study in progressive supranuclear palsy and dentatorubropallidoluysial atrophy

So-called "grumose degeneration" (GD) of the dentate nucleus (DN) which is a unique alteration in progressive supranuclear palsy and dentatorubropallidoluysial atrophy was studied by light and electron microscope. Light microscopically, the presence of a large amount of eosinophilic granular and/or amorphous material around the neurons is the most conspicuous feature of GD. In addition, the number of neurons is decreased and some of them are swollen as with central chromatolysis. Electron microscopically, the granular and/or amorphous material mainly consists of the altered axon terminals of the Purkinje cells (Pax), which are relatively electron-dense and characteristically contain varying numbers of deformed lamellar bodies, highly electron-dense mitochondria and many vacuoles which are adherent to the astrocytic processes. GD is a unique histological change of both the chromatolytic DN neurons and the grumose appearance of the altered Pax. Possible mechanisms are discussed.

Three categories of the degenerative appearance of the human cerebellar dentate nucleus. A morphometric and morphological study

This morphometric and morphological study demonstrates 3 categories (types A, B and C) of degenerative feature in the cerebellar dentate nucleus. Type A is characterized by neuronal loss, astrocytosis and granular and/or amorphous argyrophilic change around the neurons and neuronal processes, and this type was thought to be synonymous with the so-called grumose degeneration of the DN. Type B is characterized by extensive neuronal loss and astrocytosis without argyrophilic change, and it was considered that many diverse factors were responsible for type B. Type C features marked swelling of the neurons without neuronal loss, astrocytosis or argyrophilic change. The Purkinje cells were not involved in type A and C, but severely damaged in type B. Clinically, type A was observed in progressive supranuclear palsy and dentatorubropallidoluysian atrophy, type B extensively in many diseases including anoxic, toxic and infectious disorders, and type C in tardive dyskinesia manifesting with oral hyperkinesia. Types A and C may be more or less specific signs of degeneration of the dentate nucleus, whereas type B appears to be non-specific.