Functional MRI signal fluctuations highlight altered resting brain activity in Huntington's disease.

The fractional Amplitude of Low Frequency Fluctuations (fALFF) and the degree of local synchronization (Regional Homogeneity - ReHo) of resting-state BOLD signal have been suggested to map spontaneous neuronal activity and local functional connectivity, respectively. We compared voxelwise, independent of atrophy, the fALFF and ReHo patterns of 11 presymptomatic (ps-HD) and 28 symptomatic (sHD) Huntington's disease mutation carriers, with those of 40 normal volunteers, and tested their possible correlations with the motor and cognitive subscores of the Unified Huntington's Disease Rating Scale. In sHD patients, fALFF was mainly reduced bilaterally in parietal lobes (right precuneus being already affected in psHD), and in superior frontal gyri, and increased bilaterally in cerebellar lobules VI, VIII and IX, as well as in the right inferior temporal gyrus. In sHD, and to a lesser extent in psHD, ReHo was bilaterally reduced in putamina, cerebellar lobules III to VI, and superior medial frontal gyri, and increased in both psHD and sHD in fronto-basal cortices, and in the right temporal lobe. fALFF correlated inversely with cognitive scores in lobule IX of the cerebellum (mainly with total Stroop score, p < 0.0001), and in the medial portions of both thalami. These results are consistent with a reduced neuronal activity in the cortical components of the executive networks, known to be affected in Huntington's Disease, and with reduced local functional integration in subcortical and cerebellar components of the sensori-motor network. Cerebellar clusters of significant correlation of fALFF with executive function scores may be related to compensatory mechanisms.

Regulation of postsynaptic plasticity genes' expression and topography by sustained dopamine perturbation and modulation by acute memantine: relevance to schizophrenia.

A relevant role for dopamine-glutamate interaction has been reported in the pathophysiology and treatment of psychoses. Dopamine and glutamate may interact at multiple levels, including the glutamatergic postsynaptic density (PSD), an electron-dense thickening that has gained recent attention as a switchboard of dopamine-glutamate interactions and for its role in synaptic plasticity. Recently, glutamate-based strategies, such as memantine add-on to antipsychotics, have been proposed for refractory symptoms of schizophrenia, e.g. cognitive impairment. Both antipsychotics and memantine regulate PSD transcripts but sparse information is available on memantine's effects under dopamine perturbation. We tested gene expression changes of the Homer1 and PSD-95 PSD proteins in models of sustained dopamine perturbation, i.e. subchronic treatment by: a) GBR-12909, a dopamine receptor indirect agonist; b) haloperidol, a D2R antagonist; c) SCH-23390, a dopamine D1 receptor (D1R) antagonist; and d) SCH-23390+haloperidol. On the last day of treatment, rats were acutely treated with vehicle or memantine. The Homer1a immediate-early gene was significantly induced by haloperidol and by haloperidol+SCH-23390. The gene was not induced by SCH-23390 per se or by GBR-12909. Expression of the constitutive genes Homer1b/c and PSD-95 was less affected by these dopaminergic paradigms. Acute memantine administration significantly increased Homer1a expression by the dopaminergic compounds used herein. Both haloperidol and haloperidol+SCH-23390 shifted Homer1a/Homer1b/c ratio of expression toward Homer1a. This pattern was sharpened by acute memantine. Dopaminergic compounds and acute memantine also differentially affected topographic distribution of gene expression and coordinated expression of Homer1a among cortical-subcortical regions. These results indicate that dopaminergic perturbations may affect glutamatergic signaling in different directions. Memantine may help partially revert dopamine-mediated glutamatergic dysfunctions.

Different effects of the NMDA receptor antagonists ketamine, MK-801, and memantine on postsynaptic density transcripts and their topography: role of Homer signaling, and implications for novel antipsychotic and pro-cognitive targets in psychosis.

Administration of NMDA receptor antagonists, such as ketamine and MK-801, may induce psychotic-like behaviors in preclinical models of schizophrenia. Ketamine has also been observed to exacerbate psychotic symptoms in schizophrenia patients. However, memantine, a non-competitive NMDA receptor antagonist approved for Alzheimer's disease and proposed for antipsychotic augmentation, may challenge this view. To date, the molecular mechanisms by which these NMDA receptor antagonists cause different neurochemical, behavioral, and clinical effects are still a matter of debate. Here, we investigated by molecular imaging whether these agents could differently modulate gene expression and topographical distribution of glutamatergic postsynaptic density (PSD) proteins. We focused on Homer1a/Homer1b/PSD-95 signaling network, which may be implicated in glutamate-dependent synaptic plasticity, as well as in psychosis pathophysiology and treatment. Ketamine (25 and 50mg/kg) and MK-801 (0.8mg/kg) significantly induced the transcripts of immediate-early genes (Arc, c-fos, and Homer1a) in cortical regions compared to vehicle, whereas they reduced Homer1b and PSD-95 expression in cortical and striatal regions. Differently, memantine (5mg/kg) did not increase Homer1a signal compared to vehicle, whereas it induced c-fos in the somatosensory and in the medial agranular cortices. Moreover, memantine did not affect Homer1b and PSD-95 expression. When compared to ketamine and MK-801, memantine significantly increased the expression of c-fos, Homer1b and PSD-95. Overall, ketamine and MK-801 prominently increased Homer1a/Homer1b expression ratio, whereas memantine elicited the opposite effect. These data may support the view that ketamine, MK-801 and memantine exert divergent effects on PSD transcripts, which may contribute to their partially different behavioral and clinical effects.

The expression of genes involved in glucose metabolism is affected by N-methyl-D-aspartate receptor antagonism: a putative link between metabolism and an animal model of psychosis.

Psychosis has been associated with glucose metabolism impairment. Here, we explored the gene expression of hexokinase 1 (Hk1) and glucose transporter 3 (GLUT3) after the administration of a subanesthetic or a subconvulsant dose of ketamine in rats, considered to provide an animal model of psychosis. Indeed, Hk1 and GLUT3 are crucially involved in the glucose utilization in brain tissues and have also been implicated in the pathophysiology of psychosis. Quantitative brain imaging of transcripts was used to evaluate Hk1 and GLUT3 mRNA in rat brain regions related to ketamine-induced behavioral abnormalities. Hk1 transcript was significantly increased by 50 mg/kg ketamine in cortical and subcortical areas, whereas 12 mg/kg ketamine affected Hk1 expression in the auditory cortex only. GLUT3 expression was increased by 12 mg/kg ketamine in the frontal cortex and decreased by 50 mg/kg ketamine in subcortical areas. The results show that Hk1 and GLUT3 are extensively and differentially affected by ketamine dose, supporting the view that glucose metabolism and psychosis may be causally related and suggesting that these molecules may play a role in the pathophysiology of ketamine-induced behavioral abnormalities.

Targeting glutamate system for novel antipsychotic approaches: relevance for residual psychotic symptoms and treatment resistant schizophrenia.

Antipsychotics are the mainstay of schizophrenia treatment. However, approximately one third of schizophrenic patients do not respond or respond poorly to antipsychotics. Therefore, there is a need for new approaches that can improve schizophrenia treatment significantly. Promising strategies arise from the modulation of glutamatergic system, according to its proposed involvement in schizophrenia pathogenesis. In this review, we critically updated preclinical and clinical data on the modulation of glutamate N-methyl-D-aspartate (NMDA) receptor activity by NMDA-Rs co-agonists, glycine transporters inhibitors, AMPAkines, mGluR5 agonists, NMDA-Rs partial agonists. We focused on: 1) preclinical results in animal models mimicking the pathophysiology of psychosis, mainly believed to be responsible of negative and cognitive symptoms, and predicting antipsychotic-like activity of these compounds; and 2) clinical efficacy in open-label and double-blind trials. Albeit promising preclinical findings for virtually all compounds, clinical efficacy has not been confirmed for D-cycloserine. Contrasting evidence has been reported for glycine and D-serine, that may however have a role as add-on agents. More promising results in humans have been found for glycine transporter inhibitors. AMPAkines appear to be beneficial as pro-cognitive agents, while positive allosteric modulators of mGluR5 have not been tested in humans. Memantine has been proposed in early stages of schizophrenia, as it may counteract the effects of glutamate excitotoxicity correlated to high glutamate levels, slowing the progression of negative symptoms associated to more advanced stages of the illness.

[Personality disorder and penal imputability: a case of uxoricide in a expert's report]. / Disturbo di personalità e imputabilità: intervento peritale in un caso di uxoricidio.

The personality disorders are generally described as a persistent pattern of inner experience that deviates strongly from the expectations of the culture of an individual in terms of cognition, affectivity, interpersonal functioning and impulse control. They are a complex area of defining and understanding for the clinical and forensic psychiatrist. A recent ruling by the Court of Cassation stated that personality disorder may be a result of reduction or cancellation of the ability to understand and will, if so serious as to affect the same. In the present work is explored, using a psycho-diagnostic protocol, the psychological profile of a person with a narcissistic personality disorder, charged for uxoricidio.

The clinical spectrum and natural history of gelastic epilepsy-hypothalamic hamartoma syndrome.

PURPOSE: To delineate the clinical spectrum and patterns of evolution of epilepsy with gelastic seizures related to hypothalamic hamartoma (HH). PATIENTS AND METHODS: We evaluated patients with HH, observed between 1986 and 2002 for whom at least one ictal video-EEG or EEG recording of gelastic seizures was available. RESULTS: Six subjects (four male, two female) with sessile HH between 0.8 and 1.7 cm in diameter were identified. The onset of gelastic seizures was between 2 months and 20 years. It evolved to secondary generalized epilepsy in one case, and to drug-resistant partial epilepsy in the other five from 2 to 13 years after onset. No patient showed precocious puberty. Severe cognitive impairment developed in the patient with secondary generalized epilepsy, and a mild cognitive defect in two others. Patients with an HH below 1cm did not show neuropsychological or behavioural disturbances. Drug resistance occurred in all cases. Surgical removal of HH markedly improved the clinical evolution in two patients. CONCLUSIONS: Gelastic epilepsy-HH syndrome can differ in severity and evolution. A catastrophic evolution and drug resistance can be reversed by surgical or by gamma-knife ablation of HH.

Spinal muscular atrophy and progressive myoclonic epilepsy: one case report and characteristics of the epileptic syndrome.

INTRODUCTION: Spinal muscular atrophies (SMAs) are a group of degenerative diseases primarily affecting the anterior horn cells of the spinal cord and motor cells of cranial nerve nuclei. Even if the clinical picture is mainly dominated by the diffuse muscular atrophy, in some cases, patients may show associated, atypical clinical features ("SMA plus"). In particular, the association of SMA and progressive myoclonic epilepsy (PME) has been rarely described. CASE REPORT: We present the clinical and electrophysiological data of a boy with childhood-onset SMA associated with PME and reviewed cases of the literature. CONCLUSION: The association of SMA with PME may constitute a separate and, probably, genetically independent syndrome with unique clinical and electroencephalographic findings or, at least, a variant of a neurodegenerative or metabolic disease, due to yet unknown causes.