Convergent roles of alpha-synuclein, DA metabolism, and the ubiquitin-proteasome system in nigrostriatal toxicity.

Recent studies disclosed the relevance of specific molecules for the onset of Parkinson's disease (PD) and for the composition of neuronal inclusions. The scenario which is now emerging leads to identify a potential common pathway named the ubiquitin-proteasome (UP) system. In line with this, striatal or systemic inhibiton of the UP system causes experimental Parkinsonism characterized by the formation of neuronal inclusions. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), which is also a complex I inhibitor, has been used for decades to produce experimental Parkinsonism with no evidence for neuronal inclusions in rodents. This leaves open the question whether neuronal inclusions need an alternative mechanism or the inhibition of complex I needs to be carried out continuously to build up inclusions. In the present article, we administered continuously MPTP. In these experimental conditions we compared the neurological consequence of intermittent versus continuous MPTP. In both cases we observed a severe dopamine (DA) denervation and cell loss. However, when MPTP was delivered continuously, spared DA nigral neurons develop ubiquitin, parkin, and alpha-synuclein positive inclusions, which are not detectable after intermittent dosing. The onset of Parkinsonism is associated with inhibition of the UP system. We compared these results with those obtained with amphetamine derivative in vivo and in vitro in which occurrence of neuronal inclusions was associated with inhibition of the UP system and we evaluated the role of DA metabolism in inducing these effects.

Comparison between heroin and heroin-cocaine polyabusers: a psychopathological study.

The concomitant use of cocaine by heroin-dependent subjects, or by patients on methadone maintenance treatment, is a relevant phenomenon that determines the negative consequences on health, social adjustment, and outcome of opioid addiction treatment. Little is known about the patterns of co-use of these two substances and the pathophysiological alterations following this condition. Only a few studies have evaluated the neurochemical effects in subjects carrying this specific pattern of abuse. Similarly, the impact of cocaine abuse on psychiatric and social function in subjects already affected by opioid addiction is still poorly understood and further studies are necessary to investigate this specific area that could profoundly affect methadone maintenance treatment. The aim of this article is to investigate the psychopathological symptoms of heroin-cocaine abuse in a group of heroin addicts applying for treatment. Results show a direct relationship between cocaine abuse and a higher rate of psychiatric disorders, but a negative correlation with the severity of self-rated psychopathology.

Clozapine in treatment-resistant patients with schizophrenia, schizoaffective disorder, or psychotic bipolar disorder: a naturalistic 48-month follow-up study.

BACKGROUND: The aim of this study was to evaluate the long-term efficacy and safety of clozapine in patients with treatment-resistant schizophrenia, schizoaffective disorder, or bipolar disorder with psychotic features. METHOD: 101 patients with a DSM-III-R diagnosis of schizophrenia (N = 34); schizoaffective disorder, bipolar type (N = 30); or bipolar disorder with psychotic features (N = 37) were naturalistically treated with clozapine at flexible doses over a 48-month period. Data were collected from 1994 to 2000. The Brief Psychiatric Rating Scale (BPRS) and Clinical Global Impressions-Severity of Illness scale total predicted scores over time were estimated with random-effects regression models. Time to response to clozapine, defined as 50% reduction of BPRS score, was analyzed in the 3 diagnostic groups using the Kaplan-Meier method. Survival curves were compared using the log-rank test. RESULTS: The BPRS total predicted score halved its baseline value in 3 months for bipolar disorder patients, in 6 months for schizoaffective disorder patients, and in 24 months for schizophrenia patients. The proportion of subjects who satisfied the criterion for response to clozapine after 48 months of follow-up was significantly (p <.01) higher in the schizoaffective and bipolar disorder groups (90.0% and 83.8%, respectively) than in the schizophrenia group (64.7%). Baseline scores on the Global Assessment of Functioning (GAF) showed low levels of psychosocial and occupational functioning in all 3 groups. After 48 months of treatment, GAF scores showed a functional improvement in all 3 groups, with significantly (p <.01) greater improvement in the bipolar disorder group compared with the other groups. CONCLUSION: The findings of this study confirm the efficacy and safety of clozapine for treatment-resistant patients with a diagnosis of schizophrenia, schizoaffective disorder, or bipolar disorder with psychotic features. Patients with schizoaffective disorder and those with bipolar disorder show greater clinical improvement than those with schizophrenia. Patients with bipolar disorder have the shortest time to response and the highest psychosocial and occupational functioning levels. Patients with schizoaffective disorder have the lowest treatment discontinuation rate.