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Query: UMLS:C0036341 (schizophrenia)
 60,220 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although life prevalence of substance use disorders among patients with schizophrenia is close to 50%, few studies have been carried out to date to identify an integrated pharmacological treatment for this comorbidity. So far, the most promising results, that we report here, have been obtained with clozapine. To a lesser extent, quetiapine and olanzapine, both clozapine analogues, have also shown promising results. Further to these observations, the present paper critically reviews the advantages associated with clozapine, quetiapine and olanzapine, and their relevance to the treatment of addiction among schizophrenic patients. Six characteristics seem to distinguish clozapine, quetiapine and olanzapine from the first-generation antipsychotics: (1) acting preferentially on the reward system, these second-generation antipsychotics (mainly clozapine and quetiapine) induce almost no extrapyramidal symptoms; (2) quickly dissociating from D(2), theses drugs (mainly clozapine and quetiapine) seem not to induce dysphoria, unlike conventional antipsychotics like haloperidol;(3) these drugs (mainly clozapine) seem more effective in the treatment of negative symptoms than conventional antipsychotics; (4) because of a diversified activity on several serotoninergic and noradrenergic receptors, these drugs positively alter mood, which does not seem to be the case with conventional antipsychotics, except for flupenthixol; (5) these drugs have a positive impact on cognition, which is not the case with the first-generation antipsychotics; (6) unlike conventional antipsychotics, these drugs seem to have a moderate affinity for 5-HT(3), the receptor on which ondansetron, an anti-craving medication, acts.
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PMID:Clozapine, quetiapine and olanzapine among addicted schizophrenic patients: towards testable hypotheses. 1270 90

The basal ganglia are implicated in a number of disorders including neurodegenerative motor diseases such as Huntington's and Parkinson's disease, as well as psychiatric disorders such as schizophrenia and obsessive compulsive disorder. In recent years, a great deal of effort has been focused on determining the basal ganglia circuitry that underlies normal behavior, as well as many of these syndromes. This has led to a detailed understanding of both the normal and pathophysiological flow of information through the basal ganglia, and has provided the opportunity to begin developing novel pharmacological methods of intervention by targeting neuromodulatory receptors with in the basal ganglia circuit. One group of receptors that holds much promise for several basal ganglia disorders is the metabotropic glutamate receptors. Data from behavioral, neurochemical, neuroanatomical and electrophysiological studies has begun to reveal the functional roles that the metabotropic glutamate receptors play in modulating the basal ganglia circuit, and suggests that compounds selectively targeting these receptors may provide novel therapies for a variety of disorders including Parkinson's disease, addiction, and epilepsy.
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PMID:Modulation of the basal ganglia by metabotropic glutamate receptors: potential for novel therapeutics. 1276 17

Despite the fact that most researchers acknowledge the high prevalence of comorbid substance abuse among schizophrenic patients, there is no common agreement regarding the etiology of this serious public health problem. At the center of this debate though, Khantzian's self-medication hypothesis has captured most of the attention. In the present literature review, the authors evaluate this hypothesis in the light of our current knowledge. Formulated in a clinical context, in reaction to the psychoanalytic interpretation of addiction as a pleasure seeking pathology, Khantzian's hypothesis holds that schizophrenic patients use psychoactive substances to relieve their symptoms. Properly understood, this conjecture presupposes that, with the relief of certain target symptoms, substance use would no more be a necessity. But in reality, the use of psychoactive substances usually leads to a general deterioration of the patients' condition. Pharmacodependent schizophrenic patients relapse more often, they are more frequently hospitalized, they show more violent behaviors, and they are more frequently homeless. In particular, the positive symptoms of these patients are generally exacerbated by the psychoactive drugs--with the possible exception of opiates. This observation is in lign with the fact that psychostimulants (cocaine, amphetamines), anesthesic dissociatives (PCP, ketamine) as well as hallucinogens (cannabis, LSD) are all known to exert psychotomimetic effects. As for negative symptoms, the reality is more complex. Preliminary results certainly suggest that stimulants (minor or major) relieve these symptoms, but in the case of the other psychoactive substances, empirical evidence remains fragmentary. Still, the properties of psychoactive substances invite to pay close attention, among the negative symptoms, to the cognitive deficits, the social inaptitudes and the hedonic deficits of these patients. Unsatisfied with the self-medication hypothesis, an increasing number of researchers hypothesize that schizophrenic patients abuse drugs in hope to relieve the negative affects (stress, depression) that commonly accompany their symptomatology. Interestingly, increasing data link these negative manifestations and substance abuse among schizophrenic patients. But these same data do not elucidate whether these manifestations are primary or secondary to drug abuse. For the moment, these findings must be replicated. Furthermore, it remains to be clarified what negative affect is involved here. Is it stress, anxiety or, as commonly thought, depression? Other paths aim in the direction of personality traits and dissociation. The first path is suggested by recent studies demonstrating that pharmacodependent schizophrenic patients differ from non-abusing schizophrenics in that their personality is characterized by traits such as sensation seeking and impulsivity. As for the second path, it is suggested by a recurrent observation in addictive medicine practice, that is: alcohol, cannabis, ketamine, LSD, opiates, PCP, all these substances can induce dissociative states (depersonalization, derealization, etc.). Surprisingly, most of the hypotheses advanced so far have been formulated without reference to neuroscience. However, from a biological perspective, substance abuse among schizophrenic patients appears paradoxical: while the positive symptoms of schizophrenia might involve an hyperactivity of the reward system, the drugs of abuse all seem to increase dopamine release in that same system. That very paradox further casts some doubt on the self-medication hypothesis. And it opens an alternative: schizophrenic patients might be biologically vulnerable to the rewarding effects of drugs abuse. On the therapeutic level finally, the authors argue that polypharmacy medications such as clozapine and quetiapine, known to act on the reward system preferentially to the extrapyramidal system and known to dissociate fastly from the dopamine-D2 receptor, could simplify clinical intervention.
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PMID:[Schizophrenia and addiction: An evaluation of the self-medication hypothesis]. 1287 43

Schizophrenic patients suffer from positive (delusions, hallucinations) and negative signs (social withdrawal) as well as emotional disturbance that included quantitative (blunted affect) and qualitative impairments (discordance of emotional level). Ketamine, a phencyclidine derivative, is a non competitive N-methyl-D-aspartate (NMDA) glutamate receptor antagonist. In healthy subjects its administration induces some positive symptoms (perceptual distortions.), negative symptoms (emotional deficit, apathy, social withdrawal) and cognitive changes (memory impairments and perseverations) that resemble some aspects of the symptoms of schizophrenia. A double blind cross over, placebo controlled was performed in 12 normal subjects with 2 sessions separated by one week of wash-out to determine ketamine-induced effects on behavioral and emotional responses. During each session, subjects received either ketamine or placebo (saline) infusion. A subanesthetic dose of ketamine (0,5 mg/kg) was administered by constant perfusion over 60 min. Behavioral and cognitive responses were assessed using positive and negative symptoms scales (BPRS, items from SAPS and SANS), vigilance and mood visual analog scale, subjective feelings using the Addiction Research Center Inventory (ARCI) and the Profile of Mood States (POMS). Using Philippot's method, emotions were elicited by films segments which induce a diversity of predictable emotions (fear, anger, sadness, joy, disgust and neutral state) and emotional responses were assessed by the Differential Emotions Scale (DES Izard). Low dose of ketamine induced significant effects on 7-items BPRS score (positive and negative items) and significant effects on positive and negative symptoms from SANS and SAPS. This was associated with emotional blunting of visually-induced responses that resemble aspects of schizophrenic emotional impairments. Ketamine impaired ARCI subscales (benzedrine subscale, pentobarbital-chlorpromazine subscale and LSD subscale). The recent findings of ketamine's pharmacology and imaging studies allow to draw several hypothesis related to neurotransmitter systems (glutamate, dopamine, serotonin interactions) and cerebral areas (particularly prefrontal cortex, anterior cingulate cortex, hippocampus) underlying some of these ketamine-induced effects.
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PMID:[Effects of a subanaesthetic dose of ketamine on emotional and behavioral state in healthy subjects]. 1290 92

Molecular epidemiologic studies suggest genetic factors in the etiology of smoking behavior. Dopamine receptor genes, transporter genes (serotonin and dopamine), and other genes related to metabolism of nicotine are plausible functional candidate genes. Research examining the role of allelic variation in those genes is being actively pursued with respect to nicotine dependence as well as personality characteristics and mental disorders. Some of these genes were reported to be connected with schizophrenia. Although nicotine dependence itself is one of the mental disorders according to the fourth edition of Diagnostic and Statistical Manual of Mental Disorders and the World Health Organization's International Statistical Classification of Diseases and Related Health Problems-10 nomenclature, the high comorbidity between nicotine dependence and other mental disorders such as schizophrenia or affective disorders has been noted. Therefore, the relationship between those mental disorders and tobacco addiction should be cleared up considering the interactive effect of genetic and environmental factors.
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PMID:Genetic influences on smoking behavior and nicotine dependence: a review. 1293 61

Striatal cholinergic interneurons located in the dorsal striatum and nucleus accumbens are amenable to influences of the dopaminergic mesolimbic pathway, which is a pathway involved in reward and reinforcement and targeted by several drugs of abuse. Dopamine and acetylcholine neurotransmission and their interactions are essential to striatal function, and disruptions to these systems lead to a variety of clinical disorders. Dopamine regulates acetylcholine release through dopamine receptors that are localized directly on striatal cholinergic interneurons. The dopamine D2 receptor, which attenuates acetylcholine release, has been implicated in drug relapse and is targeted by therapeutic drugs that are used to treat a variety of neurological disorders including Tourette Syndrome, Parkinson's disease and schizophrenia. The present study provides the first direct evidence for the localization of dopamine D2 receptors on striatal cholinergic interneurons of the rat brain using dual labeling immunocytochemistry procedures. Using light microscopy, dopamine D2 receptors were localized on the cell somata and dendritic and axonal processes of striatal cholinergic interneurons in the dorsal striatum and nucleus accumbens of the rat brain. These findings provide a foundation for understanding the specific roles that cholinergic neuronal network systems and interacting dopaminergic signaling pathways play in striatal function and in a variety of clinical disorders including drug abuse and addiction.
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PMID:Localization of dopamine D2 receptors on cholinergic interneurons of the dorsal striatum and nucleus accumbens of the rat. 1296 26

Two case reports of ecstasy abuse and its serious neuropsychiatric complications are presented. The first patient developed a florid paranoid psychosis resembling schizophrenia after repeated long-term recreational ecstasy abuse, and significant alterations with intermittent paroxysmal discharges were found in his electroencephalogram. The second patient showed an atypical paranoid psychosis with Fregoli syndrome and a series of complex-partial epileptic seizures with secondary generalization after a first single ecstasy dose. Both subjects presented considerable vulnerability; the first a minimal brain dysfunction after perinatal asphyxia and a persisting attention deficit/hyperactivity disorder, the second a long-lasting opioid addiction. In vulnerable individuals, dose-independent ecstasy abuse can lead to unpredictable and potentially dangerous neuropsychiatric sequelae which require proper initial assessment and adequate treatment.
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PMID:Neuropsychiatric consequences (atypical psychosis and complex-partial seizures) of ecstasy use: possible evidence for toxicity-vulnerability predictors and implications for preventative and clinical care. 1451 28

Tobacco addiction among persons with serious mental illness (SMI) has been largely ignored. About 75 to 85% of persons with schizophrenia, bipolar disorder, and other SMI use tobacco; most will either die and/or have reduced quality of life because of tobacco-caused medical diseases. Tobacco addiction is the most common co-occurring disorder for the SMI population. A dramatic reduction in tobacco use in the general population has occurred during the past 40 years; however, there has been almost no reduction for smokers with SMI. The University of Medicine and Dentistry of New Jersey program targets smokers with SMI and provides outreach services, clinical treatment and research, and consultation to other community-based mental health treatment agencies in New Jersey. Clinical and research evidence supports motivation-based treatment, blending mental health and addiction treatment approaches, and integrating tobacco dependence treatment within mental health settings. The unique barriers and clinical issues for this population are described.
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PMID:Serious mental illness and tobacco addiction: a model program to address this common but neglected issue. 1455 39

Brickman et al.'s (Brickman, P., Rabinowitz, V. C., Coates, D., Cohn, E., Kidder, L. (1982). Models of helping and coping. American Psychologist 37:364-384.) models of helping and coping provided a framework by which to compare clinicians' attributions of blame and control among several hypothetical patients. Sixty-one mental health clinicians (MHCs) and addiction clinicians (ACs)--mostly master's level clinicians and registered nurses--rated attributions toward vignettes that depicted individuals with schizophrenia, alcoholism, and mentally ill, chemically addicted (MICA) classifications in 1995. Results indicate that MHCs attributed more blame to MICA patients than did ACs, but did not differ on their attributions of control. MHCs' and ACs' attributions of blame and control were generally low, consistent with a medical model. However, the endorsement of a disease model of alcoholism did not significantly predict the amount of blame attributed by the clinicians. Implications for treatment planning for MICA patients are discussed.
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PMID:Clinician attributions and disease model perspectives of mentally ill, chemically addicted patients: a preliminary investigation. 1467 83

Nicotine addiction is the single largest preventable cause of morbidity and mortality in the Western World. Smoking is not any more just a bad habit, but a substance addiction problem. The pharmacological aspects of nicotine show that this substance has a broad distribution in the different body compartnents, due mainly to its lipophilic characteristic. There are nicotinic receptors as members of cholinergic receptors' family. They are located in neuromuscular junction and in the central nervous system (CNS). Although they are similar, pentameric structure with an ionic channel to sodium, there are some differences in the protein chains characteristics. Repeated administration of nicotine in rats, results in the sensitization phenomenon, which produces increase in the behavioral locomotor activity response. It has been found that most psychostimulants-induced behavioral sensitization through a nicotine receptor activation. Nicotine receptors in CNS are located mainly in presynaptic membrane and in that way they regulated the release of several neurotransmitters, among them acetylcholine, dopamine, serotonin, and norepinephrine. In some activities like sleep-wake cycle, nicotine receptors have a functional significance. Nicotine receptor stimulation promotes wake time, reduces both, total sleep time and rapid eye movement sleep (REMS). About nicotine dependence, this substance full fills all the criteria for dependence and withdrawal syndrome. There are some people that have more vulnerability for to become nicotine dependent, those are psychiatric patients. Among them schizophrenia, major depression, anxiety disorders and attention deficit disorder, represent the best example in this area. Nicotine may have some beneficial effects, among them are some neuroprotective effects in disorders like Parkinson's disease, and Gilles de la Tourette' syndrome. Also there are several evidences that support the role of nicotine in cognitive improvement functions like attention, concentration, and memory. Finally there are several strategies to deal with nicotine dependence, Nicotine Replacement Therapy (NRT), which are nicotine chewing-gum, transdermal nicotine patches, and nicotine inhalators device. Also some antidepressants like bupropion has shown to be effective in smoking cessation treatment. To know more about nicotine phenomenon would be important, because that will allow a more mature perspective about the damage and beneficial effects of that substance.
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PMID:Nicotine dependence and psychiatric disorders. 1501 38


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