Warum rauchen Schizophreniepatienten?

Discovery and Development of Non-Dopaminergic Agents for the Treatment of Schizophrenia: Overview of the Preclinical and Early Clinical Studies

Schizophrenia is a chronic psychiatric disorder that affects about 1 in 100 people around the world and results in persistent emotional and cognitive impairments. Untreated schizophrenia leads to deterioration in quality of life and premature death. Although the clinical efficacy of dopamine D2 receptor antagonists against positive symptoms of schizophrenia supports the dopamine hypothesis of the disease, the resistance of negative and cognitive symptoms to these drugs implicates other systems in its pathophysiology. Many studies suggest that abnormalities in glutamate homeostasis may contribute to all three groups of schizophrenia symptoms. Scientific considerations also include disorders of gamma-aminobutyric acid-ergic and serotonergic neurotransmissions as well as the role of the immune system. The purpose of this review is to update the most recent reports on the discovery and development of non-dopaminergic agents that may reduce positive, negative, and cognitive symptoms of schizophrenia, and may be alternative to currently used antipsychotics. This review collects the chemical structures of representative compounds targeting metabotropic glutamate receptor, gamma-aminobutyric acid type A receptor, alpha 7 nicotinic acetylcholine receptor, glycine transporter type 1 and glycogen synthase kinase 3 as well as results of in vitro and in vivo studies indicating their efficacy in schizophrenia. Results of clinical trials assessing the safety and efficacy of the tested compounds have also been presented. Finally, attention has been paid to multifunctional ligands with serotonin receptor affinity or phosphodiesterase inhibitory activity as novel strategies in the search for dedicated medicines for patients with schizophrenia.

Association of social support and quality of life among people with schizophrenia receiving community psychiatric service: A cross-sectional study

OBJECTIVE

To understand the needs of patients with schizophrenia for recovery, this study examined the type and level of social support and its association with quality of life (QOL) among this group of patients in the city of Kuala Lumpur.

METHOD

A cross-sectional study was conducted on 160 individuals with schizophrenia receiving community psychiatric services in Hospital Kuala Lumpur (HKL). The WHOQOL-BREF, Brief Psychiatric Rating Scale (BPRS) and Multidimensional Scale of Perceived Social Support (MSPSS) were used to assess QOL, severity of symptoms and social support, respectively. The study respondents were predominantly Malay, aged less than 40, males, single, unmarried, had lower education levels and unemployed.

RESULTS

About 72% of the respondents had poor perceived social support, with support from significant others being the lowest, followed by friends and family. From multiple regression analysis, social support (total, friend and family) significantly predicted better QOL in all domains; [B=0.315 (p<0.001), B=0.670 (p<0.001), B=0.257 (p<0.031)] respectively in Physical Domain; [B=0.491 (p<0.001), B=0.735 (p<0.001), B=0.631 (p<0.001)] in Psychological Domain; [B=1.065 (p<0.001), B=0.670 (p<0.017), B=2.076 (p<0.001)] in Social Domain and; [B=0.652 (p<0.001), B=1.199 (p<0.001), B=0.678 (p<0.001)] in Environmental Domain. Being married and having shorter duration of illness, lower BPRS (total) scores, female gender and smoking, were also found to significantly predict higher QOL.

CONCLUSION

Social support is an important missing component among people with schizophrenia who are already receiving formal psychiatric services in Malaysia.

[Substance use associated disorders: frequency in patients with schizophrenic and affective psychoses]

BACKGROUND

Alcohol and substance use disorders (ASUD) are considered to be among the most frequent comorbidities in schizophrenic and affective psychoses and have a significant negative influence on their course and prognosis. In the present study patients with diagnosis from the ICD-10 category F2 or F3 were examined regarding a substance use disorder in a multicentre cross-section evaluation at nine psychiatric hospitals in Baden-Württemberg. The aim of this study is to discuss the current research on substance use disorders and psychosis comorbidity regarding the theoretical models by means of collected data.

METHODS

The examination of 50 consecutive admissions per centre is based on a shortened version of the European Severity Index (Europ ASI). An initial urine drug screening was carried out with all patients after admission. Statistical assessment was based on percentage distributions, mean values, standard deviations and suitable correlation analysis.

RESULTS

The representative sample included 448 patients. A proportion of 169 patients (37.7%) had a dual diagnosis F2 and F1 and a proportion of 144 patients (32.1%) had a dual diagnosis F3 and F1; 64 patients (14.3%) had an F2 diagnosis and 71 patients (15.8%) had an F3 diagnosis without ASUD. Apart from lifetime use of alcohol (n = 268) and tobacco (n = 325) hypnotics/tranquilizers (n = 214), cannabis (n = 156), opioids (n = 71), stimulants (n = 96) and hallucinogens (n = 36) were consumed. The most frequent combination and long-term intake consisted of tobacco, alcohol, hypnotics/tranquilizer, cannabis and psychostimulants especially in men with schizophrenic disorders. Regarding motivation before first substance use general psychological adjustment disorders (51%), peer impact (42%) and unspecific affective symptoms were predominant.

CONCLUSIONS

Altogether the present study clearly demonstrates that patients suffering from schizophrenia, affective disorders and ASUD have significantly higher rates of more severe substance use disorders in their psychosocial environment and more suicidal behaviour than patients without substance misuse. The high rate in the cross-sectional prevalence of tobacco, alcohol, cannabis and psychostimulant use calls for more effective drug prevention.

Decreased psychological well-being in late 'chronotypes' is mediated by smoking and alcohol consumption

Individuals are different 'chronotypes' with early 'larks' and late 'owls' forming the limits of a normal distribution in the population. We recently described that late chronotypes who suffer from a conflict between internal and external time ('social jetlag') suffer from more mental distress and are more likely to smoke than early chronotypes (Wittmann, Dinich, Merrow, and Roenneberg, 2006 . Social jetlag: mis-alignment of biological and social time. Chronobiology International, 23:497-509.). We performed a detailed analysis of the same database collected in 2002 comprising 134 daily smokers and 366 nonsmokers, scrutinizing the relationships between chronotype, smoking, and alcohol consumption as well as psychological well-being using a multiple mediation analysis. On average, smokers tend to be later chronotypes, report more sleep-associated psychosomatic symptoms, are more depressed, less balanced, and less vigilant. The mediation analysis suggests that only those late chronotypes who smoke and those who drink more suffer from increased psychological distress. We suggest that 'chronotype' is introduced as an additional factor in substance use, that is, when considering motives for smoking and drinking.

Chronic nicotine and dizocilpine effects on nicotinic and NMDA glutamatergic receptor regulation: interactions with clozapine actions and attentional performance in rats

Blockade of NMDA glutamate receptors with dizocilpine (MK-801) has been shown to cause substantial cognitive deficits and has been used to model symptoms of schizophrenia. Nicotine or nicotinic agonists, in contrast, may enhance cognitive or attentional functions and be of therapeutic potential in schizophrenia. Nicotinic-glutamatergic interactions, therefore, may have important implications in cognitive functions and antipsychotic treatments. Clozapine, a widely used antipsychotic drug, has been shown in some studies to be effective in ameliorating the cognitive deficits associated with schizophrenia. However, there is some evidence to suggest that clozapine similar to haloperidol may impair sustained attention in rats. In this study, we sought to determine whether chronic nicotine or dizocilpine may modify the effects of acute clozapine on attentional parameters and whether the behavioral effects would correlate with nicotinic or NMDA receptor densities in discrete brain regions. Adult female rats trained on an operant visual signal detection task were given 4 weeks of nicotine (5 mg/kg/day), dizocilpine (0.15 mg/kg/day), the same doses of both nicotine and dizocilpine as a mixture, or saline by osmotic minipump. While on chronic treatment, rats received acute injections of various doses of clozapine (0, 0.625, 1.25, 2.5 mg/kg, sc) 10 min prior to tests on attentional tasks. The pumps were removed on day 28 and 24 h later the animals were sacrificed for measurements of receptor densities in specific brain regions. The percent correct hit as a measure of sustained attention was significantly impaired by clozapine in a dose-related manner. Neither chronic nicotine nor dizocilpine affected this measure on their own or modified the effects of clozapine. Both nicotine and dizocilpine affected the receptor bindings in a region specific manner and their combination further modified the effects of each other in selective regions. Attentional performance was inversely correlated with alpha-bungarotoxin binding in the frontal cortex only. In conclusion, the data suggest attentional impairments with clozapine alone and no modification of this effect with nicotine or dizocilpine. Moreover, cortical low affinity nicotinic receptors may have a role in attentional functions.