Occupancy of dopamine D2 receptors by antipsychotic drugs is related to nicotine addiction in young patients with schizophrenia

Associations between antipsychotic use, substance use and relapse risk in patients with schizophrenia: real-world evidence from two national cohorts

BACKGROUND

Research on the effectiveness of pharmacotherapies for schizophrenia and comorbid substance use disorder (SUD) is very sparse, and non-existent on the prevention of the development of SUDs in patients with schizophrenia.

AIMS

To compare the real-world effectiveness of antipsychotics in schizophrenia in decreasing risk of developing an initial SUD, and psychiatric hospital admission and SUD-related hospital admission among patients with an SUD.

METHOD

Two independent national cohorts including all persons diagnosed with schizophrenia (N = 45 476) were followed up for 22 (Finland: 1996-2017) and 11 (Sweden: 2006-2016) years. Risk of developing an SUD was calculated with between-individual models, and risks of psychiatric and SUD-related hospital admission were calculated with within-individual models, using Cox regression and adjusted hazard ratios (aHRs) for using versus not using certain antipsychotics.

RESULTS

For patients with schizophrenia without an SUD, clozapine use (Finland: aHR 0.20, 95% CI 0.16-0.24, P < 0.001; Sweden: aHR 0.35, 95% CI 0.24-0.50, P < 0.001) was associated with lowest risk of developing an initial SUD in both countries. Antipsychotic polytherapy was associated with second lowest risk (aHR 0.54, 95% CI 0.44-0.66) in Sweden, and third lowest risk (aHR 0.47, 95% CI 0.42-0.53) in Finland. Risk of relapse (psychiatric hospital admission and SUD-related hospital admission) were lowest for clozapine, antipsychotic polytherapy and long-acting injectables in both countries. Results were consistent across both countries.

CONCLUSIONS

Clozapine and antipsychotic polytherapy are most strongly associated with reduced risk of developing SUDs among patients with schizophrenia, and with lower relapse rates among patients with both diagnoses.

Potent Dopamine D2 Antagonists Block the Reward-Enhancing Effects of Nicotine in Smokers With Schizophrenia

Antipsychotics that are potent dopamine (DA) D2 receptor antagonists have been linked to elevated levels of nicotine dependence in smokers with schizophrenia. Because activation of D2 receptors mediates motivation for nicotine, we examined whether potent D2 antagonists would diminish nicotine's ability to stimulate reward processing-a mechanism that may drive compensatory increases in smoking. Smokers with schizophrenia (n = 184) were recruited and stratified into medication groups based on D2 receptor antagonist potency. The effects of smoking on reward function were assessed using a probabilistic reward task (PRT), administered pre- and post-smoking. The PRT used an asymmetrical reinforcement schedule to produce a behavioral response bias, previously found to increase under conditions (including smoking) that enhance mesolimbic DA signaling. Among the 98 participants with valid PRT data and pharmacotherapy that could be stratified into D2 receptor antagonism potency, a medication × smoking × block interaction emerged (P = .005). Post-hoc tests revealed a smoking × block interaction only for those not taking potent D2 antagonists (P = .007). This group exhibited smoking-related increases in response bias (P < .001) that were absent in those taking potent D2 antagonists (P > .05). Our findings suggest that potent D2 antagonists diminish the reward-enhancing effects of nicotine in smokers with schizophrenia. This may be a mechanism implicated in the increased rate of smoking often observed in patients prescribed these medications. These findings have important clinical implications for the treatment of nicotine dependence in schizophrenia.

Psychopathology and extrapyramidal side effects in smoking and non-smoking patients with schizophrenia: Systematic review and meta-analysis of comparative studies

The association between smoking and psychopathology and extrapyramidal side effects (EPSE) in schizophrenia has been controversial. This systematic review and meta-analysis compared psychopathology and EPSE between smoking and non-smoking schizophrenia patients. The PubMed, EMBASE, PsycINFO, Cochrane Library, and Web of Science databases were independently and systematically searched by two researchers to identify relevant articles. Standardized mean differences (SMDs) and their 95% confidence intervals (CI) were calculated with random effect models. Subgroup and meta-regression analyses were performed to explore sources of heterogeneity. The systematic review and meta-analysis included 29 studies that compared psychotic, depressive and anxiety symptoms and EPSE between smoking (n = 3591) and non-smoking schizophrenia patients (n = 2980). Smoking patients had significantly more severe positive symptoms (24 studies; SMD = 0.33, 95% CI: 0.16 to 0.50, P < 0.001), but less severe EPSE (7 studies; SMD = -0.20, 95% CI: -0.38 to -0.02, P = 0. 03). No significant group differences in negative, depressive and anxiety symptoms were found. In conclusion, this systematic review and meta-analysis found that smoking schizophrenia patients had more severe positive symptoms but less severe EPSE than non-smoking patients.

Tobacco smoking is associated with antipsychotic medication, physical aggressiveness, and alcohol use disorder in schizophrenia: results from the FACE-SZ national cohort

Tobacco smoking is common in schizophrenia and is one of the main causes of premature mortality in this disorder. Little is known about clinical correlates and treatments associated with tobacco smoking in patients with schizophrenia. Still, a better characterization of these patients is necessary, in a personalized care approach. Aggressiveness and childhood trauma have been associated with tobacco smoking in general population, but this association has never been explored in schizophrenia. Our study examines the clinical and therapeutic characteristics of tobacco smoking in schizophrenia. 474 stabilized patients (mean age = 32.2; 75.7% male gender; smokers n = 207, 54.6%) were consecutively included in the network of the FondaMental Expert centers for Schizophrenia and assessed with valid scales. Current tobacco status was self-declared. Aggressiveness was self-reported with Buss-Perry Aggressiveness Questionnaire and Childhood Trauma with Childhood Trauma Questionnaire. Ongoing treatment was reported. In univariate analysis, tobacco smoking was associated with lower education level (p < 0.01), positive syndrome (p < 0.01), higher physical aggressiveness (p < 0.001), alcohol dependence (p < 0.001), and First Generation Antipsychotics (FGAs) use (p = 0.018). In a multivariate model, tobacco smoking remained associated with physical aggressiveness (p < 0.05), current alcohol dependence (p < 0.01) and FGA use (p < 0.05). No association was observed with childhood trauma history, mood disorder, suicidal behavior, psychotic symptom, global functioning or medication adherence. Patients with tobacco use present clinical and therapeutic specificities, questioning the neurobiological links between tobacco and schizophrenia. They could represent a specific phenotype, with specific clinical and therapeutic specificities that may involve interactions between cholinergic-nicotinic system and dopaminergic system. Further longitudinal studies are needed to confirm the potential efficacy of second generation antipsychotics (SGAs) on tobacco use in schizophrenia and to develop effective strategies for tobacco cessation in this population.

What proportion of striatal D2 receptors are occupied by endogenous dopamine at baseline? A meta-analysis with implications for understanding antipsychotic occupancy

Using molecular imaging techniques - positron emission tomography (PET) and single-photon emission computed tomography (SPECT) - in conjunction with an acute dopamine depletion challenge (alpha-methyl-para-tyrosine) it is possible to estimate endogenous dopamine levels occupying striatal dopamine D₂ receptors (D₂R) in humans in vivo. However, it is unclear what proportion of striatal D₂R are occupied by endogenous dopamine under normal conditions. This is important since it has been suggested that in schizophrenia there may be a substantial proportion of striatal D₂R which are occupied by endogenous dopamine and not accessible by therapeutic doses of antipsychotics. In order to clarify these issues, we conducted a meta-analysis of dopamine depletion studies using substituted benzamide radiotracers in healthy persons. This meta-analysis suggests that anywhere from 8 to 21% (weighted average 11%) of striatal D₂R may be occupied by endogenous dopamine at baseline. Using these estimates, we propose an updated occupancy model and tentatively suggest that antipsychotics inhibit a smaller proportion of the total pool of striatal D₂R in vivo than previously acknowledged. This article is part of the issue entitled 'Special Issue on Antipsychotics'.

Comparing the effect of clozapine and risperidone on cue reactivity in male patients with schizophrenia and a cannabis use disorder: A randomized fMRI study

OBJECTIVE

Cannabis use disorders (CUDs) are highly comorbid in patients with schizophrenia and associated with poor outcome. Clozapine has been put forward as the first choice antipsychotic in this patient group. However, little is known about the mechanisms underlying the assumed superiority of clozapine.

METHODS

A total of 38 patients with DSM-IV schizophrenia (30 with and 8 without a DSM-IV CUD) and 20 healthy comparison subjects were included between April 2009 and June 2012. Patients were randomized to antipsychotic treatment with clozapine or risperidone. At baseline and after 4weeks of medication, brain response to cannabis-related, positive and neutral images was measured using functional MRI. Neural correlates of cue reactivity were assessed in the following regions of interest: amygdala, ventral striatum, insula, thalamus, orbitofrontal cortex and anterior cingulate cortex. Subjective craving was assessed using self-report questionnaires (OCDUS and MCQ).

RESULTS

At baseline, patients with a comorbid CUD showed higher subjective craving and greater activation in response to cannabis-related images compared to patients without a CUD and healthy controls in most regions of interest. Clozapine treated patients reported a greater reduction in craving (F(1,28)=6.0, p=0.04) and showed a larger decrease in amygdala activation during cannabis-related images compared to risperidone treated patients (T=3.94, pFWE=0.006). In addition, significant correlations were found between subjective craving and thalamus and insula activation during cannabis-related images.

CONCLUSION

These findings provide evidence that clozapine is superior to risperidone in decreasing subjective craving and cue reactivity for cannabis-related images probably due to a differential effect on dopaminergic neurotransmission.

TRIAL REGISTRATION

'Nederlands trial register' (http://www.trialregister.nl), nr NTR1761, http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=1761.

Cigarette smoking and schizophrenia: a specific clinical and therapeutic profile? Results from the FACE-Schizophrenia cohort

BACKGROUND

Tobacco use is common in patients with schizophrenia (SZ) but little is known on the role of tobacco in the physiopathology or on the course of the disease. Only few studies embrace an extensive examination of clinical and therapeutic characteristics in stabilized patients. The objective of the present study was to determine the prevalence of tobacco smoking in stabilized SZ outpatients and the clinical and treatment characteristics associated with daily tobacco use in a large community-dwelling sample of patients.

METHODS

Three-hundred-and-sixty-one patients were included in the network of the FondaMental Expert Centers for Schizophrenia. Current tobacco status was self-declared.

RESULTS

53.7% were smokers. Mean age at tobacco onset was 17.2years old. In multivariate analyses, after adjustment for confounding factors, positive symptoms and mean daily antipsychotic dose were associated with a higher frequency of tobacco use (OR=1.06 95%IC[1.02-1.12], for positive symptoms, OR=1.1, 95%IC[1.02-1.18] for daily antipsychotic dose). Education level, negative symptoms, anticholinergic agents, clozapine or aripiprazole administration were independently associated with a lower frequency of tobacco use (respectively OR=0.87, 95%IC [0.79, 0.95], OR=0.95, 95%IC[0.91-0.98], OR=0.41, 95%IC[0.22-0.76], OR=0.56, 95%IC=[0.32, 0.99] and OR=0.49, 95%IC [0.26-0.91]).

CONCLUSION

The prevalence of current tobacco smoking in a French community-dwelling SZ patients is higher that observed in the general population. Patients with tobacco use present clinical and therapeutic specificities that may involve interaction between cholinergic-nicotinic and dopaminergic systems. The present study suggests that some therapeutics may improve daily smoking behavior in smokers. These results should be confirmed in longitudinal studies.

An association between the PPARα-L162V polymorphism and nicotine dependency among patients with schizophrenia

OBJECTIVE

Patients with schizophrenia are more likely to be smokers than the general population, which makes them an interesting group with which to study the etiology of nicotine dependency. We studied the prevalence of a gene variant of peroxisome proliferator-activated receptor alpha (PPARα) in schizophrenia, together with nicotine dependency, to investigate whether the PPARα-L162V polymorphism (rs1800206) influences nicotine dependency in schizophrenia. Given evidence suggesting that smoking influences the severity of schizophrenia, together with our recent data linking the PPARα-L162V polymorphism to clinical manifestations of schizophrenia (in the Croatian population), we hypothesized that interactions between the two (smoking and the PPARα-L162V polymorphism) might contribute to disease onset and scores for the Positive and Negative Syndrome Scale. To the best of our knowledge, this is the first study to investigate the possible associations between the PPARα gene and nicotine dependency.

PATIENTS AND METHODS

Genotyping was performed for 267 chronically ill schizophrenia patients (males/females: 140/127) by polymerase chain reaction.

RESULTS

A significant excess of PPARα-L162V genotypes and PPARα-162V alleles were detected among female smokers in comparison to female nonsmokers (18.2% vs. 2.0%, and 9.1% vs. 1.0%, p<0.01, respectively). We also revealed a significant PPARα genotype-smoking interaction that predicted positive symptom severity among male patients (F=4.43, p<0.05). These data indicated that the PPARα-L162V heterozygous genotype, depending on smoking status, might be of relevance as either protective, or a risk factor, for the severity of positive symptoms. No interaction between the PPARα-L162V polymorphism and smoking for the time of onset of schizophrenia was detected (p>0.05, respectively).

CONCLUSION

We demonstrated two significant yet weak effects. The first showed an effect of the PPARα-L162V polymorphism on the risk of nicotine dependency. The second linked the PPARα genotype-smoking interaction to positive symptoms severity among schizophrenia patients; both effects manifested in a gender-specific fashion.

Attenuated Positive Psychotic Symptoms in Relation to Cigarette Smoking in a Nonclinical Population

INTRODUCTION

This study explored the association between cigarette smoking and attenuated positive psychotic symptoms in a young adult nonclinical sample.

METHODS

Undergraduates (N = 930), aged 18-35 years (26.3% male), completed a battery of self-report measures assessing subthreshold psychotic symptoms, cigarette smoking behavior/dependence, and drug use.

RESULTS

Individuals endorsing a greater number of attenuated positive psychotic symptoms were more likely to be smokers. Exploratory analyses indicated that the odds of being a smoker were two times greater for those at potential higher risk for psychosis compared with individuals at lower risk. Results were consistent after adjusting for sex and other drug use.

CONCLUSIONS

In line with findings from psychotic populations, results suggest that attenuated positive psychotic symptoms, particularly those endorsed as distressing in a nonclinical, undergraduate population, are related to cigarette smoking.

IMPLICATIONS

Even in nonclinical, undergraduate populations, subthreshold psychotic symptoms are related to cigarette smoking, and cigarette smokers are twice as likely to be considered at potentially higher risk for psychosis compared with noncigarette smokers. In summary, there may be a threshold whereby psychotic symptoms confer increased risk for nicotine consumption, with endorsement of a greater number of distressing subthreshold psychotic symptoms increasing the likelihood of cigarette use.

Smoking in schizophrenic patients: A critique of the self-medication hypothesis

A common remark among laypeople, and notably also among mental health workers, is that individuals with mental illnesses use drugs as self-medication to allay clinical symptoms and the side effects of drug treatments. Roots of the self-medication concept in psychiatry date back at least to the 1980s. Observations that rates of smokers in schizophrenic patients are multiple times the rates for regular smoking in the general population, as well as those with other disorders, proved particularly tempting for a self-medication explanation. Additional evidence came from experiments with animal models exposed to nicotine and the identification of neurobiological mechanisms suggesting self-medication with smoking is a plausible idea. More recently, results from studies comparing smoking and non-smoking schizophrenic patients have led to the questioning of the self-medication hypothesis. Closer examination of the literature points to the possibility that smoking is less beneficial on schizophrenic symptomology than generally assumed while clearly increasing the risk of cancer and other smoking-related diseases responsible for early mortality. It is a good time to examine the evidence for the self-medication concept as it relates to smoking. Our approach is to focus on data addressing direct or implied predictions of the hypothesis in schizophrenic smokers.

The effect of clozapine and risperidone on attentional bias in patients with schizophrenia and a cannabis use disorder: An fMRI study

Cannabis use disorders (CUDs) are highly comorbid in patients with schizophrenia and are associated with poor outcome. Clozapine has been put forward as the first choice antipsychotic in this comorbid group. However, little is known about the mechanisms underlying the assumed superiority of clozapine. We compared the effects of clozapine and risperidone on attentional bias, subjective craving and associated regional brain activity in patients with schizophrenia and CUD. Overall, 36 patients with schizophrenia and 19 healthy controls were included. Patients were randomised to antipsychotic treatment with clozapine or risperidone. At baseline and after 4 weeks of medication use, regional brain responses were measured during a classical Stroop and a cannabis word Stroop using functional magnetic resonance imaging. Clozapine-treated CUD patients showed a larger reduction in craving and in activation of the insula during the cannabis word Stroop, while risperidone-treated patients showed a larger decrease in activation of the right anterior cingulate cortex during the classical Stroop. A significant association was found between decreases in subjective craving and decreases in insula activation during the cannabis word Stroop. These findings strongly suggest that clozapine may be a better treatment choice in patients with schizophrenia and CUD than risperidone.

Allostatic load as a tool for monitoring physiological dysregulations and comorbidities in patients with severe mental illnesses

Severe mental illnesses like schizophrenia and bipolar disorder are disabling, chronic conditions that are often accompanied by medical comorbidities. In this theoretical article, we review the allostatic load model representing the "wear and tear" that chronic stress exacts on the brain and body. We propose an innovative way of monitoring physical and psychiatric comorbidities by integrating the allostatic load model into clinical practice. By interpreting peripheral biomarkers differently, medical professionals can calculate a simple, count-based, allostatic load index known to predict diverse stress-related pathologies. In addition to screening for comorbidities, allostatic load indices can be used to monitor the effects of pharmacological and psychosocial interventions. This framework can also be used to generate a dialogue between patient and practitioner to promote preventive and proactive approaches to health care.

Is it time to consider comorbid substance abuse as a new indication for antipsychotic drug development?

Comorbid drug abuse in schizophrenia has been consistently reported as high, with estimates ranging between 10-70%. Comorbid addictive states in schizophrenia are possibly multifactorial, yet recent research assigns a significant neurobiological role in its genesis. Abnormalities in hippocampal/cortical function in schizophrenia which mediate reward and reinforcement behavior are identified as central to the development and maintenance of comorbid addictive states. Preliminary data suggest that the vulnerability of patients with schizophrenia to substance use disorders may be a primary disease symptom. The management of comorbid substance abuse in schizophrenia relies on the use of antipsychotic medications. Recent data raise the concern about whether first-generation antipsychotics in long-term use can conversely lead to enhancement of the abused substance's reinforcing properties. Some recent reports have assigned a favorable outcome to clozapine and second-generation antipsychotics, pointing to a possible differential role for various antipsychotics. In view of the high prevalence of comorbid drug abuse in schizophrenia, its impact on outcome of treatment and the recent emerging neurobiological information, it is my contention that comorbid drug abuse constitutes a dimension by itself and deserves to receive an indication in the development of new antipsychotics similar to negative symptoms or cognitive deficits.

Differences in craving for cannabis between schizophrenia patients using risperidone, olanzapine or clozapine

Substance abuse and psychotic disorders have a high rate of comorbidity. Both disorders are associated with changes in the dopaminergic transmission in the mesocorticolimbic pathways of the brain. Since antipsychotic medications interact with the dopamine receptors in these pathways, these medications could affect craving for substances. In the current study, the effect of clozapine (n = 27, mean dosage 350 mg), risperidone (n = 54, mean dosage 3.46 mg) and olanzapine (n = 60, mean dosage 13.78 mg) on subjective craving for cannabis was compared in 123 patients with cannabis dependence and psychotic disorder. Patients treated with risperidone reported significantly more craving compared with patients treated with clozapine (Z = -3.19, p = .001) or olanzapine (Z = -2.24, p = .025). No significant differences in craving between clozapine and olanzapine were found. These results are in concordance with findings in the literature on this subject and could be explained by differences in three dopamine mediated mechanisms of these compounds: 1) occupancy rate of dopamine D(2) receptors, 2) dissociation rate of dopamine D(2) receptors, 3) D(1)/D(2) occupancy ratio. Risperidone and clozapine show a maximal difference in D(2) receptor occupancy rate, dissociation rate and D(1)/D(2) ratio. Olanzapine is intermediate between risperidone and clozapine in these characteristics.

Imaging as tool to investigate psychoses and antipsychotics

The results of imaging studies have played an important role in the formulation of hypotheses regarding the etiology of psychosis and schizophrenia, as well as in our understanding of the mechanisms of action of antipsychotics. Since this volume is primarily directed to molecular aspects of psychosis and antipsychotics, only the results of molecular imaging techniques addressing these topics will be discussed here.One of the most consistent findings of molecular imaging studies in schizophrenia is an increased uptake of DOPA in the striatum, which may be interpreted as an increased synthesis of L-DOPA. Also, several studies reported an increased release of dopamine induced by amphetamine in schizophrenia patients. These findings played an important role in reformulating the dopamine hypothesis of schizophrenia. To study the roles of the neurotransmitters γ-aminobutyric acid (GABA) and glutamate in schizophrenia, SPECT as well as MR spectroscopy have been used. The results of preliminary SPECT studies are consistent with the hypothesis of NMDA receptor dysfunction in schizophrenia. Regarding the GABA deficit hypothesis of schizophrenia, imaging results are inconsistent. No changes in serotonin transporters were demonstrated in imaging studies in schizophrenia, but studies of several serotonin receptors showed conflicting results. The lack of selective radiotracers for muscarinic receptors may have hampered examination of this system in schizophrenia as well as its role in the induction of side effects of antipsychotics. Interestingly, preliminary molecular imaging studies on the cannabinoid-1 receptor and on neuroinflammatory processes in schizophrenia have recently been published. Finally, a substantial number of PET/SPECT studies have examined the occupancy of receptors by antipsychotics and an increasing number of studies is now focusing on the effects of these drugs using techniques like spectroscopy and pharmacological MRI.

The role of antipsychotics in smoking and smoking cessation

Persons with severe and persistent mental illnesses, e.g. schizophrenia spectrum disorders and bipolar disorder, smoke at a much higher rate than the general population. Treatment options for schizophrenia spectrum disorders and bipolar disorder often include the first-generation (typical) and second-generation (atypical) antipsychotics, which have been shown to be effective in treating both psychotic and mood symptoms. This article reviews studies examining the relationship between antipsychotic medication and cigarette smoking. These studies suggest that in persons with schizophrenia and schizoaffective disorder, typical antipsychotics may increase basal smoking and decrease people's ability to stop smoking, whereas atypical antipsychotics decrease basal smoking and promote smoking cessation. However, we found that the data available were generally of moderate quality and from small studies, and that there were conflicting findings. The review also critically assesses a number of potential mechanisms for this effect: the use of smoking as a form of self-medication for the side effects of antipsychotics, the effect of antipsychotics on smoking-related cues and the effect of antipsychotics on the appreciation of the economic cost of smoking behaviour. Gaps in the research are noted and recommendations for further study are included. More study of this important issue is needed to clarify the effect of antipsychotics on smoking behaviours.

Extrapyramidal symptoms in substance abusers with and without schizophrenia and in nonabusing patients with schizophrenia

Extrapyramidal symptoms (EPS) such as parkinsonism, dystonia, dyskinesia, and akathisia are conditions of impaired motor function, which are associated with chronic antipsychotic treatment in schizophrenia. In addition, EPS is often exacerbated by psychoactive substance (PAS) abuse, which is frequently observed in this population. Few studies, however, have investigated the contribution of PAS abuse on EPS in PAS-abusers without comorbid psychosis. This study compared the occurrence of EPS in outpatient schizophrenia patients with (DD group; n= 36) and without PAS abuse (SCZ group; n = 41) as well as in nonschizophrenia PAS abusers undergoing detoxification [substance use disorder (SUD) group; n = 38]. Psychiatric symptoms were measured using the Positive and Negative Syndrome Scale and the Calgary Depression Scale for schizophrenia. Extrapyramidal symptoms were evaluated with the Extrapyramidal Symptoms Rating Scale and the Barnes Akathisia Scale. SUD diagnoses were complemented with urine drug screenings. We found that DD patients exhibited significantly more parkinsonism than SCZ patients. Our subanalyses revealed that cocaine and alcohol abuse/dependence was responsible for the increase in parkinsonism in DD patients. Additionally, we found that SUD individuals exhibited significantly more akathisia than SCZ patients. In these latter individuals, subanalyses revealed that alcohol and cannabis abuse/dependence was responsible for the increase in akathisia. Our results suggest that PAS abuse is a contributor to EPS in individuals with and without schizophrenia.

Unexpected detection of nodular melanoma of the skin on the scalp by I-123 IBZM brain SPECT

Melanocytes and dopaminergic neurons share the same ectodermal origin and can both produce melanin. Indeed, in vivo studies have shown that the radiopharmaceutical iodine-123-iodobenzamide (I-123 IBZM), which binds in vivo to dopamine D(2/3) receptors, is also able to detect melanoma, and particularly melanotic melanoma. We report a case of intense IBZM uptake in nodular melanoma of the skin on the scalp. The presence of unexpected focal IBZM uptake of the skin justified histologic examination, which revealed nodular melanoma. Melanoma should be considered when one is confronted with atypical focal uptake of benzamide derivatives like IBZM, in or outside the brain.

Antipsychotic agents for the treatment of substance use disorders in patients with and without comorbid psychosis

Substance dependence has serious negative consequences upon society such as increased health care costs, loss of productivity, and rising crime rates. Although there is some preliminary evidence that atypical antipsychotic agents may be effective in treating substance dependence, results have been mixed, with some studies demonstrating positive and others negative or no effect. The present study was aimed at determining whether this disparity originates from that reviewers separately discussed trials in patients with (DD) and without (SD) comorbid psychosis. Using electronic databases, we screened the relevant literature, leaving only studies that used a randomized, double-blind, placebo-controlled or case-control design that had a duration of 4 weeks or longer. A total of 43 studies were identified; of these, 23 fell into the category of DD and 20 into the category of SD. Studies in the DD category suggest that atypical antipsychotic agents, especially clozapine, may decrease substance use in individuals with alcohol and drug (mostly cannabis) use disorders. Studies in the SD category suggest that atypical antipsychotic agents may be beneficial for the treatment of alcohol dependence, at least in some subpopulations of alcoholics. They also suggest that these agents are not effective at treating stimulant dependence and may aggravate the condition in some cases.

Why do patients with schizophrenia smoke?

PURPOSE OF REVIEW

Among the mentally ill, smoking prevalence is highest in patients with schizophrenia ( approximately 70-80%). This can impose a significant financial burden on patients, not to speak of increased smoking-related morbidity and mortality. Therefore, it is critical for clinicians to understand why patients with schizophrenia smoke in order to adapt treatment schemes. Understanding the reasons may also help to develop new drugs that target the nicotinic system in the brain as well as smoking cessation programs that are specifically designed for this particular patient population.

RECENT FINDINGS

So far, several reasons have been identified which are believed to explain tobacco consumption in patients with schizophrenia. Originally, it was widely believed that patients with schizophrenia smoke to increase hepatic clearance and to restore the dopamine blockade of certain antipsychotic drugs to diminish their side effects. However, more recently it became obvious that cigarette smoking may also be reinforcing for patients because it improves psychiatric symptoms, most notably negative and cognitive symptoms. The underlying molecular mechanisms of these nicotine effects are currently under intensive investigation.

SUMMARY

Heavy smoking in schizophrenia cannot simply be viewed as a 'bad habit'. Rather, self-medication of clinical symptoms and side effects of antipsychotic drugs appear to play a major role.

Influence of antipsychotics on mortality in schizophrenia: systematic review

BACKGROUND

Antipsychotic medication is the cornerstone of schizophrenia treatment. The impact of long-term exposure to antipsychotics on life-expectancy has recently received some attention, partly because awareness is increasing of the differential mortality of people with schizophrenia and the general population.

METHODS

A systematic review of studies assessing the association between antipsychotic exposure and mortality in persons with schizophrenia was undertaken.

RESULTS

In total, 12 studies met the inclusion criteria. Three out of five studies examining antipsychotic dosage and higher mortality showed a significant association for one or more antipsychotics. Two out of four found negative effects of antipsychotic polypharmacy on life-expectancy. Some studies found a lower cardiovascular mortality risk with higher treatment intensity or when comparing current versus past or non-use of antipsychotics. Others established a stable correlation between antipsychotic exposure and an increase in cardiovascular mortality. Evidence for differential effects on mortality in favor of second generation (SGA) compared to first generation antipsychotics was inconsistent. No study of SGA drugs had a sufficient follow-up time. A major confounding factor may be a higher risk factor load for somatic disorders in the most severely mentally ill.

CONCLUSION

There is some evidence that long-term exposure to antipsychotics increases mortality in schizophrenia. More rigorously designed, prospective studies are urgently needed.

Summary of the 1st Schizophrenia International Research Society Conference oral sessions, Venice, Italy, June 21-25, 2008: the rapporteur reports

The Schizophrenia International Research Society held its first scientific conference in Venice, Italy, June 21 to 25th, 2008. A wide range of controversial topics were presented in overlapping and plenary oral sessions. These included new genetic studies, controversies about early detection of schizophrenia and the prodrome, treatment issues, clinical characteristics, cognition, neuropathology and neurophysiology, other etiological considerations, substance abuse co-morbidity, and animal models for investigating disease etiology and for use as targets in drug studies. Young investigators in the field were awarded travel grants to participate in the congress and one of their roles was to summarize the oral sessions and subsequent discussions. The reports that follow are the culmination of this work produced by 30 young investigators who attended the congress. It is hoped that these summaries will be useful synopses of what actually occurred at the congress for those who did not attend each session or were unable to be present. The abstracts of all presentations, as submitted by the authors a few months prior, were previously published as supplement 2 to volume 102/1-3, June 2008.

Effect of olanzapine and risperidone on subjective well-being and craving for cannabis in patients with schizophrenia or related disorders: a double-blind randomized controlled trial

OBJECTIVE

To examine whether subjective well-being and craving for cannabis were different in patients with schizophrenia or related disorders treated with either olanzapine or risperidone.

METHOD

A 6-week, double-blind, randomized trial of olanzapine and risperidone was carried out in 128 young adults with recent onset schizophrenia or related disorders. Primary efficacy measures were the mean baseline-to-endpoint change in total scores on the Subjective Well-Being under Neuroleptics scale, the Obsessive-Compulsive Drug Use Scale, the Drug Desire Questionnaire, and the cannabis use self-report. An analysis of covariance was used to test between-group differences.

RESULTS

Estimated D(2) receptor occupancy did not differ between olanzapine (n = 63) and risperidone (n = 65). Similar improvements in subjective well-being were found in both groups. In the comorbid cannabis-using group (n = 41, 32%), a similar decrease in craving for cannabis was found in both treatment conditions.

CONCLUSIONS

Both olanzapine and risperidone were associated with improved subjective well-being. No evidence was found for a differential effect of olanzapine or risperidone on subjective experience or on craving for cannabis in dosages leading to comparable dopamine D(2) occupancy.

CLINICAL TRIAL REGISTRATION NUMBER

ISRCTN46365995.

Treatment consideration and manifest complexity in comorbid neuropsychiatric disorders

Psychiatric disorders may co-occur in the same individual. These include, for example, substance abuse or obsessive-compulsive disorder with schizophrenia, and movement disorders or epilepsy with affective dysfunctional states. Medications may produce iatrogenic effects, for example cognitive impairments that co-occur with the residual symptoms of the primary disorder being treated. The observation of comorbid disorders in some cases may reflect diagnostic overlap. Impulsivity, impulsiveness or impulsive behaviour is implicated in a range of diagnostic conditions including substance abuse, affective disorder and obsessive-compulsive disorder. These observations suggest a need to re-evaluate established diagnostic criteria and disorder definitions, focusing instead on symptoms and symptom-profiles.

Nicotinic interactions with antipsychotic drugs, models of schizophrenia and impacts on cognitive function

People with schizophrenia often have substantial cognitive impairments, which may be related to nicotinic receptor deficits, (alpha7 and alpha4beta2), documented in the brains of people with schizophrenia. The large majority of people with schizophrenia smoke cigarettes. Thus, nicotinic interactions with antipsychotic drugs are widespread. Complementary co-therapies of novel nicotinic ligands are being developed to add to antipsychotic therapy to treat the cognitive impairment of schizophrenia. Thus, it is critical to understand the interaction between nicotinic treatments and antipsychotic drugs. Nicotinic interactions with antipsychotic drugs, are complex since both nicotine and antipsychotics have complex actions. Nicotine stimulates and desensitizes nicotinic receptors of various subtypes and potentiates the release of different neurotransmitters. Antipsychotics also act on a verity of receptor systems. For example, clozapine acts as an antagonist at a variety of neurotransmitter receptors such as those for dopamine, serotonin, norepinepherine and histamine. In a series of studies, we have found that in normally functioning rats, moderate doses of clozapine impair working memory and that clozapine blocks nicotine-induced memory and attentional improvement. Clozapine and nicotine can attenuate each other's beneficial effects in reversing the memory impairment caused by the psychototmimetic drug dizocilpine. A key to the clozapine-induced attenuation of nicotine-induced cognitive improvement appears to be its 5HT(2) antagonist properties. The selective 5HT(2) antagonist ketanserin has a similar action of blocking nicotine-induced memory and attentional improvements. It is important to consider the interactions between nicotinic and antipsychotic drugs to develop the most efficacious treatment for cognitive improvement in people with schizophrenia.

PET and SPECT imaging in psychiatric disorders

OBJECTIVES

To review recent findings from positron emission tomography (PET) and single photon emission computed tomography (SPECT) studies that investigate the pathophysiology and treatment of schizophrenia, depression, and dementia.

METHODS

We carried out a review of the literature.

RESULTS

PET and SPECT studies have provided evidence of dopamine system dysregulation in patients with schizophrenia and variable loss of monoamines in patients with depression. Antipsychotic response has been demonstrated to be associated with blockade of dopamine D2 receptors, and antidepressant response has now been linked to blockade of serotonin transporter receptors. PET and SPECT have been extensively evaluated as diagnostic procedures for dementia. Substantial progress has been made in developing radioligands that bind to amyloid deposits in the brain, which should provide new opportunities for early diagnosis and treatment monitoring in Alzheimer's disease.

CONCLUSION

Advances in PET and SPECT imaging have provided new insights into the biology of major psychiatric disorders and their treatment. In the future, we can expect that these imaging techniques will become more central to the management of psychiatric disorders.

Chronic nicotine doses down-regulate PDE4 isoforms that are targets of antidepressants in adolescent female rats

BACKGROUND

Previous data in humans and animal models has suggested connections between anxiety, depression, smoking behavior, and nicotine dependence. The importance of these connections has been confirmed by clinical studies that led to the recent FDA approval of an anti-depressant (Zyban) for use in human smoking cessation programs. Other anti-depressants (such as rolipram) specifically inhibit PDE4 phosphodiesterases.

METHODS

We used DNA microarrays to discover gene expression changes in adolescent female rats following chronic nicotine treatments, and real-time PCR assays to confirm and extend those results.

RESULTS

We found a consistent decrease in the mRNA levels encoded by the Pde4b gene in nucleus accumbens, prefrontal cortex, and hippocampus of adolescent female rats treated with .24 mg/day nicotine, and in prefrontal cortex of adolescent female rats treated with .12 mg/day nicotine. We further show that each of these brain areas produced a different profile of Pde4b isoforms.

CONCLUSIONS

Chronic nicotine treatments produce a dose-dependent down-regulation of Pde4b, which may have an antidepressant effect. This is the first report of a link between nicotine dependence and phosphodiesterase gene expression. Our results also add to the complex interrelationships between smoking and schizophrenia, because mutations in the PDE4B gene are associated with schizophrenia.

Nicotinic-antipsychotic drug interactions and cognitive function

In summary, neuronal nicotinic systems are important for a variety of aspects of cognitive function impacted by antipsychotic drugs. It has been demonstrated that antipsychotic drugs have memory and attentional impairing effects when given to unimpaired subjects. Nicotine can reduce some of these impairments, but antipsychotic drug administration can also attenuate nicotine effects. We have found that nicotinic agonists selective for alpha7 and alpha4beta2 receptor subtypes significantly improve learning and memory. Serotonergic actions of antipsychotic drugs may decrease efficacy of nicotinic co-treatments. When the antipsychotic drug clozapine and nicotine are administered to subjects with cognitive impairments caused by NMDA glutamate receptor blockade or hippocampal dysfunction they can significantly attenuate the attentional and memory impairments. Nicotine has been shown in our studies to reverse the memory impairment caused by acute clozapine-induced memory improvement. Acute risperidone and haloperidol has been shown to attenuate nicotine-induced memory improvement. We have determined the role of hippocampal alpha7 and alpha4beta2 nicotinic receptors in the neural basis of nicotinic antipsychotic interactions. Local acute and chronic hippocampal infusion of either nicotinic alpha7 or alpha4beta2 antagonists cause significant spatial working memory impairment. Chronic hippocampal nicotinic antagonist infusions have served as a model of persistent decreases in nicotinic receptor level seen in schizophrenia and Alzheimer's disease. Clozapine attenuated the memory deficit caused by chronic suppression of hippocampal alpha4beta2 receptors while the amnestic effects of clozapine were potentiated by chronic suppression of hippocampal alpha7 receptors. Nicotinic co-treatment may be a useful adjunct in the treatment of schizophrenia, to attenuate cognitive impairment of schizophrenia. Nicotine as well as selective nicotinic alpha7 and alpha4beta2 receptor agonists significantly improve working memory and attentional function. Nicotine treatment was found to be effective in attenuating the attentional and memory impairments caused by the psychototmimetic NMDA antagonist dizocilpine (MK-801), a model of the cognitive impairment of schizophrenia. Studies of the interactions of antipsychotic drugs with nicotinic agents provided quite useful information concerning possible co-treatment of people with schizophrenia with nicotinic therapy. Nicotine was found to significantly attenuate the memory impairments caused by the antipsychotic drugs clozapine and olanzapine. Interestingly, nicotine-induced cognitive improvement was significantly attenuated by the antipsychotic drug clozapine. One of the principal effects of clozapine is to block 5HT2 receptors. Ketanserin a 5HT2 antagonist significantly attenuated nicotine-induced improvements in attention and memory. Thus it appears that antipsychotic drugs with actions blocking 5HT2 receptors may limit the efficacy of nicotinic co-treatments for cognitive enhancement.