Why do patients with schizophrenia smoke?

Can antipsychotic treatment contribute to drug addiction in schizophrenia?

Individuals with schizophrenia are at very high risk for drug abuse and addiction. Patients with a coexisting drug problem fare worse than patients who do not use drugs, and are also more difficult to treat. Current hypotheses cannot adequately account for why patients with schizophrenia so often have a co-morbid drug problem. I present here a complementary hypothesis based on evidence showing that chronic exposure to antipsychotic medications can induce supersensitivity within the brain's dopamine systems, and that this in turn can enhance the rewarding and incentive motivational effects of drugs and reward cues. At the neurobiological level, these effects of antipsychotics are potentially linked to antipsychotic-induced increases in the striatal levels of dopamine D2 receptors and D2 receptors in a high-affinity state for dopamine, particularly at postsynaptic sites. Antipsychotic-induced dopamine supersensitivity and enhanced reward function are not inevitable consequences of prolonged antipsychotic treatment. At least two parameters appear to promote these effects; the use of antipsychotics of the typical class, and continuous rather than intermittent antipsychotic exposure, such that silencing of dopaminergic neurotransmission via D2/3 receptors is unremitting. Thus, by inducing forms of neural plasticity that facilitate the ability of drugs and reward cues to gain control over behaviour, some currently used treatment strategies with typical antipsychotics might contribute to compulsive drug seeking and drug taking behaviours in vulnerable schizophrenia patients.

Neurocognitive endophenotypes in schizophrenia: modulation by nicotinic receptor systems

Cigarette smoking is the leading preventable cause of death in the Western world, with a considerably higher prevalence observed in schizophrenia compared to the general population. Despite the negative health consequences of smoking heavily, it has been proposed that individuals with schizophrenia may maintain smoking behaviors to remediate symptoms associated with the disorder. Neurocognitive deficits are a core feature of schizophrenia and are present in approximately 80% of patients. Further, these deficits constitute an endophenotype of schizophrenia, as they are stable across disease phases, and are heritable. The neurocognitive deficits that are present in schizophrenia are especially debilitating, since they are associated with poor clinical and functional outcomes and community integration. Interestingly, these deficits may also constitute a vulnerability factor towards the initiation and maintenance of tobacco use. Contributing to the potential shared vulnerability between schizophrenia and tobacco dependence is a dysregulation of the nicotinic acetylcholine receptor (nAChR) system. Pre-clinical evidence has shown that nicotine affects several neurotransmitter systems, including dopamine (DA), glutamate, and γ-aminobutyric acid (GABA), and certain neuropsychological deficits associated with these neurotransmitters (reaction time, spatial working memory, sustained attention, and sensory gating) are improved after nicotine administration in patients with schizophrenia. These positive effects on neurocognition appear to be more pronounced in smokers with schizophrenia, and may be an important mechanism that explains the co-morbidity of schizophrenia and tobacco dependence.

Humanistic burden in schizophrenia: a literature review

OBJECTIVES OF THE STUDY AND BACKGROUND

Schizophrenia is a complex disease that affects 1% of the population. This disease has a considerable impact not only on patients' health and well-being but also on their surrounding environment. The costs of the disease's management remain large for individuals and society. While literature on the economic impact of schizophrenia is abundant, few studies have focused on its humanistic burden. This does not only concern patients, but also caregivers, relatives, neighbours and others in a patient's daily life. This burden appears through several dimensions, including treatment side effects and the impact on caregivers and features of the patient's environment. The aim of this review is to consider, compile and describe the humanistic burden of schizophrenia as documented in the literature.

MATERIALS AND METHODS

We conducted a literature review assessing the worldwide disease burden of schizophrenia, taking into account all humanistic burden topics. The search considered several databases, including Embase, Medline, Cochrane Library, The German Institute of Medical Documentation and Information (DIMDI) and the ISPOR conference websites.

RESULTS

The search identified 200 literature reviews, covering several dimensions of humanistic burden and documenting many issues. Main findings included the high death rates that may be explained by long-lasting negative health habits, disease- and treatment-related metabolic disorders, and consequent increased frequencies of cardiovascular diseases. Co-existing depression was found to have adverse consequence on the course of schizophrenia progression, morbidity and mortality. Cognitive impairment also adds to the burden of schizophrenia. Social impairment is worsened by underestimated stigmatisation and lack of corresponding awareness within the professional and social spheres. Finally, caregiver burden was found to be considerable.

DISCUSSION

Humanistic burden among patients with schizophrenia is substantial potentially impacted by co-morbid depressive symptoms, caregiver burden and cognitive impairment. Effects of treatment on humanistic burden in addition to economic burden need to be explored in future trials.

The opinion of patients with mental disorder about tobacco and its prohibition in psychiatric hospitalization

Objective: To identify the opinion of patients with mental disorder about tobacco and its prohibition during psychiatric hospitalization. Method: An exploratory study with 96 patients smokers with mental disorders hospitalized in a psychiatric ward of a general hospital. The interviews were conducted individually, using an instrument designed for this study. The content from the interviews was recorded, transcribed and submitted to a thematic content analysis. Results: The patients with mental disorder were identified as perceiving smoking during the psychiatric hospitalization as a help to support the difficulties in socialization and in the lack of activities. The permission for smoking is seen as a signal of respect to their needs. The subjects mentioned to not accept the total smoking prohibition. Conclusion: Tobacco helps to face difficulties and conflicts in the psychiatric hospitalization. There is resistance regarding the possibility to totally withdraw the smoking permission during hospitalization.



Anhedonia in obsessive-compulsive disorder: beyond comorbid depression

Obsessive-compulsive disorder (OCD) has been linked to reward dysfunctions, highlighting a possible role of anhedonia in OCD. Surprisingly, anhedonia in OCD has never been evaluated. Moreover, although nicotine typically has anti-anhedonic effects, anecdotal reports suggest low prevalence rates of smoking in OCD. To address these two phenomena, 113 individuals with OCD completed a battery of questionnaires assessing symptom severity, anhedonia, and smoking. 28.3% of the sample met criteria for clinically significant anhedonia, which correlated with Y-BOCS scores (r=0.44), even when controlling for depressive symptoms. 13.3% of the sample endorsed current smoking, a lower rate than seen in psychiatric disorders (40-90%) and the general adult population (19%). Results highlight high rates of anhedonia and yet reduced prevalence of smoking in OCD. In contrast to the known positive association between anhedonia and smoking, a negative association emerged. Future research is needed to address the unique interface between anhedonia and reward responsiveness in OCD. Potential clinical implications are discussed.

Impaired sleep quality and sleep duration in smokers-results from the German Multicenter Study on Nicotine Dependence

Cigarette smoking is a severe health burden being related to a number of chronic diseases. Frequently, smokers report about sleep problems. Sleep disturbance, in turn, has been demonstrated to be involved in the pathophysiology of several disorders related to smoking and may be relevant for the pathophysiology of nicotine dependence. Therefore, determining the frequency of sleep disturbance in otherwise healthy smokers and its association with degree of nicotine dependence is highly relevant. In a population-based case-control study, 1071 smokers and 1243 non-smokers without lifetime Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Axis I disorder were investigated. Sleep quality (SQ) of participants was determined by the Pittsburgh Sleep Quality Index. As possible confounders, age, sex and level of education and income, as well as depressiveness, anxiety, attention deficit hyperactivity, alcohol drinking behaviour and perceived stress, were included into multiple regression analyses. Significantly more smokers than non-smokers (28.1% versus 19.1%; P < 0.0001) demonstrated a disturbed global SQ. After controlling for the confounders, impaired scores in the component scores of sleep latency, sleep duration and global SQ were found significantly more often in smokers than non-smokers. Consistently, higher degrees of nicotine dependence and intensity of smoking were associated with shorter sleep duration. This study demonstrates for the first time an elevated prevalence of sleep disturbance in smokers compared with non-smokers in a population without lifetime history of psychiatric disorders even after controlling for potentially relevant risk factors. It appears likely that smoking is a behaviourally modifiable risk factor for the occurrence of impaired SQ and short sleep duration.

Influence of antipsychotic treatment type and regimen on the functionality of patients with schizophrenia

BACKGROUND

Enhanced functionality is a major goal in the treatment of schizophrenia. However, possible differences in the effectiveness of first- vs. second-generation antipsychotics or between depot/long-acting injectable (D/LAI) vs. D/LAI plus oral antipsychotics are not clear.

AIMS

This study was designed to evaluate possible differences between the effects of different antipsychotic treatment types or regimens on the functionality of patients with schizophrenia.

METHODS

85 outpatients with schizophrenia, who were being treated with D/LAI antipsychotics--co-administered or not with oral antipsychotics--and had been adherent to the treatment during the previous year were evaluated. Socio-demographic, clinical, treatment-related, global severity and functionality variables were evaluated. Patients were grouped according to the type of antipsychotic drug (first- vs. second-generation) or according to the co-administration (or not) of oral antipsychotics.

RESULTS

No differences were found between first- and second-generation antipsychotics in terms of global functionality. Patients treated with LAI risperidone showed better global functionality and better performance in their habitual social activities and personal-social relationships than patients treated with risperidone plus oral second-generation antipsychotics. Better functionality was also found to be associated with higher education level, paranoid subtype of schizophrenia, harmful use of nicotine, adherence to oral treatment and absence of concomitant oral anticholinergic or psychopharmacological treatment.

CONCLUSIONS

Our results suggest that D/LAI antipsychotic treatments should be administered in monotherapy whenever possible and that the treatment schedule should be simple, in order to achieve better functionality.

Smoking cessation and reduction in schizophrenia (SCARIS) with e-cigarette: study protocol for a randomized control trial

Background

It is well established in studies across several countries that tobacco smoking is more prevalent among schizophrenic patients than the general population. Electronic cigarettes are becoming increasingly popular with smokers worldwide. To date there are no large randomized trials of electronic cigarettes in schizophrenic smokers. A well-designed trial is needed to compare efficacy and safety of these products in this special population.

Methods/Design

Intervention: We have designed a randomized controlled trial investigating the efficacy and safety of electronic cigarette. The trial will take the form of a prospective 12-month randomized clinical study to evaluate smoking reduction, smoking abstinence and adverse events in schizophrenic smokers not intending to quit. We will also monitor quality of life, neurocognitive functioning and measure participants’ perception and satisfaction of the product.

Outcome measures: A ≥50% reduction in the number of cigarettes/day from baseline, will be calculated at each study visit (“reducers”). Abstinence from smoking will be calculated at each study visit (“quitters”). Smokers who leave the study protocol before its completion and will carry out the Early Termination Visit or who will not satisfy the criteria of “reducers” and “quitters” will be defined “non responders”.

Statistical analysis: The differences of continuous variables between the three groups will be evaluated with the Kruskal-Wallis Test, followed by the Dunn multiple comparison test. The differences between the three groups for normally distributed data will be evaluated with ANOVA test one way, followed by the Newman-Keuls multiple comparison test. The normality of the distribution will be evaluated with the Kolmogorov-Smirnov test. Any correlations between the variables under evaluation will be assessed by Spearman r correlation. To compare qualitative data will be used the Chi-square test.

Discussion

The main strengths of the SCARIS study are the following: it’s the first large RCT on schizophrenic patient, involving in and outpatient, evaluating the effect of a three-arm study design, and a long term of follow-up (52-weeks).

The goal is to propose an effective intervention to reduce the risk of tobacco smoking, as a complementary tool to treat tobacco addiction in schizophrenia.

Trial registration

ClinicalTrials.gov, NCT01979796.

Smoking status as a potential confounder in the study of brain structure in schizophrenia

Several but not all MRI studies have reported volume reductions in the hippocampus and dorsolateral prefrontal cortex (DLPFC) in patients with schizophrenia. Given the high prevalence of smoking among schizophrenia patients and the fact that smoking has also been associated with alterations in brain morphology, this study evaluated whether a proportion of the known gray matter reductions in key brain regions may be attributed to smoking rather than to schizophrenia alone. We examined structural MRI data of 112 schizophrenia patients (53 smokers and 59 non-smokers) and 77 healthy non-smoker controls collected by the MCIC study of schizophrenia. An automated atlas based probabilistic method was used to generate volumetric measures of the hippocampus and DLPFC. The two patient groups were matched with respect to demographic and clinical variables. Smoker schizophrenia patients showed significantly lower hippocampal and DLPFC volumes than non-smoker schizophrenia patients. Gray matter volume reductions associated with smoking status ranged between 2.2% and 2.8%. Furthermore, we found significant volume differences between smoker patients and healthy controls in the hippocampus and DLPFC, but not between non-smoker patients and healthy controls. Our data suggest that a proportion of the volume reduction seen in the hippocampus and DLPFC in schizophrenia is associated with smoking rather than with the diagnosis of schizophrenia. These results may have important implications for brain imaging studies comparing schizophrenia patients and other groups with a lower smoking prevalence.

Prevalence and correlates of cigarette smoking among Chinese schizophrenia inpatients receiving antipsychotic mono-therapy

Objective

To investigate the prevalence rate of cigarette smoking and its socio-demographic and clinical correlates in Chinese schizophrenia inpatients receiving antipsychotic mono-therapy.

Methods

This study was a cross-sectional, two-site, hospital-based survey. Four hundred and twenty-nine schizophrenia patients (male/female: 66.9% vs. 33.1%) were consecutively recruited from psychosis inpatient wards of two large specialty psychiatric hospitals in mainland China. Patients were assessed using a cigarette smoking questionnaire, the Positive and Negative Symptom Scale, the Simpson Angus Scale, the Barnes Akathisia Rating Scale, and the Abnormal Involuntary Movement Scale. Socio-demographic and other clinical data were also collected. We calculated the prevalence of current smoking in our sample as well as its indirectly standardized prevalence ratio (ISPR) using data from the 2010 Global Adult Tobacco Survey in China.

Results

The prevalence rate of current smoking was 40.6% in our sample, and 57.5% in males and 6.3% in females. The ISPRs of all patients, men and women were 1.11(95%CI: 0.95∼1.29), 1.07(95%CI = 0.91∼1.24) and 4.64(95%CI = 2.12∼8.82), respectively. The overall and male-specific prevalence of current smoking did not differ significantly between patients and the general population. In multiple logistic regression analysis, male sex, older age, poor marital status, alcohol use, use of first-generation antipsychotics, longer duration of illness, more frequent hospitalizations, and more severe negative symptoms were independently associated with current smoking.

Conclusion

Male Chinese inpatients with schizophrenia who received a mono-therapy of antipsychotics were not more likely to smoke than the general population. Cigarette smoking is more common in schizophrenia patients with more severe illness.

Acute effects of mecamylamine and varenicline on cognitive performance in non-smokers with and without schizophrenia

RATIONALE

Nicotinic acetylcholine receptors (nAChRs) have been implicated in the pathophysiology of cognitive deficits in the domains of attention and memory in schizophrenia. While nicotinic agonists and antagonists have been proposed as smoking cessation aids, few comparisons have been made of these agents on cognitive performance in individuals with schizophrenia.

OBJECTIVES

This study investigated the acute effects of a nAChR antagonist, mecamylamine, and partial agonist, varenicline, on cognitive function in non-smokers with and without schizophrenia.

METHODS

Single oral doses of mecamylamine 10 mg, varenicline 1 mg, and placebo were administered 1 week apart in random order to adults with schizophrenia (n = 30) and to healthy volunteers (n = 41) in a double-blind, crossover design. The primary outcome of interest was sustained attention as assessed with hit reaction time variability (HRT-SD) on the identical pairs continuous performance test (CPT-IP).

RESULTS

Mecamylamine worsened performance on CPT-IP HRT-SD, a measure of attention, compared to varenicline in both groups. Performance on mecamylamine was worse than performance on both placebo and varenicline on several additional measures of attention, including CPT-IP hit reaction time (HRT) and random errors at various levels of task difficulty. There was a treatment by diagnosis interaction, such that mecamylamine worsened performance on CPT-IP 2-digit HRT, 3-digit random errors, and 4-digit hit rate compared to placebo and varenicline in participants with schizophrenia; effects not observed in controls.

CONCLUSIONS

These findings support a role for nAChRs in attention and suggest that those with schizophrenia may be particularly sensitive to nAChR blockade.

The nicotinergic receptor as a target for cognitive enhancement in schizophrenia: barking up the wrong tree?

RATIONALE

Cognitive symptoms have increasingly been recognized as an important target in the development of future treatment strategies in schizophrenia. The nicotinergic neurotransmission system has been suggested as a potentially interesting treatment target for these cognitive deficits. However, previous research yielded conflicting results, which may be explained by several methodological limitations, such as the failure to include both a group of smoking and non-smoking schizophrenic patients, the use of only a single nicotine dose, and the inclusion of a very limited cognitive battery.

OBJECTIVES

The present study aims at investigating the cognitive effects of nicotine in schizophrenia while addressing these methodological issues.

METHODS

In a double-blind placebo-controlled randomized crossover design, cognitive effects are assessed in smoking (n =16) and non-smoking (n =16) schizophrenic patients after receiving active (1 or 2 mg) or placebo oromucosal nicotine spray.

RESULTS

A modest improving effect of nicotine on attention in the smoking but not the non-smoking group was found. No enhancing effects were found on measures of visual memory, working memory, processing speed, psychomotor speed, or social cognitive functioning in either patient group.

CONCLUSIONS

These findings suggest that the nicotinic receptor only has limited value as a cognitive treatment target in schizophrenia.

Adjunctive treatment for cognitive impairment in patients with chronic schizophrenia: a double-blind, placebo-controlled study

Cognitive impairment is closely related to real-life functioning in patients with schizophrenia. The aim of the present study was to evaluate the effects of adjunctive treatment with donepezil on cognition in patients with chronic schizophrenia. This was a 12-week, double-blind, randomized, placebo-controlled study of donepezil as an adjunct to antipsychotic drug therapy in patients with chronic stable schizophrenia. Sixty-one subjects were randomized to receive donepezil 5 mg/day (n=31) and/or placebo (n=30). A nine-test neuropsychological assessment battery was administered at baseline and at the end of the study. At the 12-week end point, the donepezil group showed significant improvements in the Wechsler Memory Scale Third Edition Spatial Span, Brief Visuospatial Memory Test total recall and delayed recall, Trail-Making Test Part A, and Category Fluency Test-animal naming (all P≤0.018). Compared with placebo, donepezil was associated with significant improvement in several cognitive domains, including working memory, speed of information processing, and visual learning and memory (P≤0.008). The results of the present study suggest that adjunctive use of donepezil is beneficial for improving cognitive function in patients with schizophrenia.

Unmet needs in the management of schizophrenia

Studies on unmet needs during the last decades have played a significant role in the development and dissemination of evidence-based community practices for persistent schizophrenia and other severe mental disorders. This review has thoroughly considered several blocks of unmet needs, which are frequently related to schizophrenic disorders. Those related to health have been the first block to be considered, in which authors have examined the frequent complications and comorbidities found in schizophrenia, such as substance abuse and dual diagnosis. A second block has been devoted to psychosocial and economic needs, especially within the field of recovery of the persistently mentally ill. Within this block, the effects of the current economic difficulties shown in recent literature have been considered as well. Because no patient is static, a third block has reviewed evolving needs according to the clinical staging model. The fourth block has been dedicated to integrated evidence-based interventions to improve the quality of life of persons with schizophrenia. Consideration of community care for those reluctant to maintain contact with mental health services has constituted the fifth block. Finally, authors have aggregated their own reflections regarding future trends. The number of psychosocial unmet needs is extensive. Vast research efforts will be needed to find appropriate ways to meet them, particularly regarding so-called existential needs, but many needs could be met only by applying existing evidence-based interventions. Reinforcing research on the implementation strategies and capacity building of professionals working in community settings might address this problem. The final aim should be based on the collaborative model of care, which rests on the performance of a case manager responsible for monitoring patient progress, providing assertive follow-up, teaching self-help strategies, and facilitating communication among the patient, family doctor, mental health specialist, and other specialists.

Structural connectivity in schizophrenia and its impact on the dynamics of spontaneous functional networks

The neuropathology of schizophrenia remains unclear. Some insight has come from modern neuroimaging techniques, which offer an unparalleled opportunity to explore in vivo the structure and function of the brain. Using functional magnetic resonance imaging, it has been found that the large-scale resting-state functional connectivity (rsFC) in schizophrenia--measured as the temporal correlations of the blood-oxygen-level-dependent (BOLD) signal--exhibit altered network topology, with lower small-world index. The origin of these rsFC alterations and link with the underlying structural connectivity remain unclear. In this work, we used a computational model of spontaneous large-scale brain activity to explore the role of the structural connectivity in the large-scale dynamics of the brain in health and schizophrenia. The structural connectomes from 15 adolescent patients with early-onset schizophrenia and 15 age- and gender-matched controls were built from diffusion tensor imaging data to detect the white matter tracts between 90 brain areas. Brain areas, simulated using a reduced dynamic mean-field model, receive excitatory input from other areas in proportion to the number of fibre tracts between them. The simulated mean field activity was transformed into BOLD signal, and the properties of the simulated functional networks were analyzed. Our results suggest that the functional alterations observed in schizophrenia are not directly linked to alterations in the structural topology. Instead, subtly randomized and less small-world functional networks appear when the brain operates with lower global coupling, which shifts the dynamics from the optimal healthy regime.

Higher psychological distress is associated with unintentional injuries in US adults

BACKGROUND

Links between mental illness, self-inflicted injury and interpersonal violence are well recognised, but the association between poor mental health and unintentional injuries is not well understood.

METHODS

We used the 2010 National Health Interview Survey to assess the association between psychological distress and unintentional non-occupational injuries among US adults. Psychological distress was measured by the Kessler Psychological Distress Scale, a symptom scale shown to identify community-dwelling persons with mental illness. Multivariable logistic regression was used to estimate adjusted ORs (AOR) and 95% CIs.

RESULTS

Of the 26,776 individuals analysed, 2.5% reported a medically attended unintentional injury in the past 3 months. Those with moderate and severe psychological distress had 1.5 (1.2 to 1.8) and 2.0 (1.4 to 2.8) times higher odds of injury, respectively, as compared to those with low distress levels, after adjusting for age, sex, race, marital status, education level, alcohol use, physical functional limitation, medical comorbidity, employment status and health insurance status. Psychological distress was significantly associated with falls (AOR 1.4 (1.1 to 1.9)) and sprain/strain injuries (AOR 2.0 (1.5 to 2.8)), but not transportation-related injuries (AOR 1.2 (0.7 to 1.9)) or fractures (AOR 1.1 (0.8 to 1.6)).

CONCLUSIONS

Among community-dwelling US adults, psychological distress is significantly associated with unintentional non-occupational injury, and the magnitude of association increases with severity of distress. The association between psychological distress and injury may be particularly strong for falls and sprain/strain injuries. These findings draw attention to a large group of at-risk individuals that may merit further targeted research, including longitudinal studies.

Variants in the 15q25 gene cluster are associated with risk for schizophrenia and bipolar disorder

BACKGROUND

Rates of tobacco smoking are significantly higher in patients with schizophrenia compared with the general population. The underlying mechanism for this comorbidity is unclear. One hypothesis is that there are common genetic factors that predispose to both nicotine dependence (ND) and schizophrenia. To investigate this hypothesis, we examined the association of the 15q25 gene cluster, the most significant candidate region to date implicated in ND and smoking behavior, with schizophrenia and bipolar disorder.

METHODS

Five variants in the 15q25 gene cluster (rs951266, rs16969968, rs1051730, rs8040868, and rs17477223) were selected to test for association with schizophrenia diagnosis, bipolar disorder diagnosis, and the presence of negative symptoms of schizophrenia. Effects of the variants on 15q25 gene expression were analyzed using publically available postmortem brain expression data.

RESULTS

A meta-analysis revealed four markers associated with risk for schizophrenia and bipolar disorder (rs951266, rs16969968, rs8040868, and rs17477223), and with the presence of negative symptoms of schizophrenia (rs951266, rs1051730, rs8040868, and rs17477223). The associations were in the same direction as that found for ND. Gene expression analysis indicated an association between genotypes of the rs1051730 variant and CHRNA5 expression in brain and peripheral blood mononuclear cells, and with the rs16969968 and rs17477223 variants in brain.

CONCLUSION

Variants in the 15q25 gene cluster are associated with risk for schizophrenia/bipolar illness, negative symptoms of schizophrenia, and influence CHRNA5 expression in the brain and peripheral blood mononuclear cells. These results are consistent with the notion that there are genetic mechanisms common to schizophrenia, ND, and bipolar disorder.

Baseline dependency of nicotine's sensory gating actions: similarities and differences in low, medium and high P50 suppressors

Reduced suppression of the P50 auditory event-related potential in schizophrenia patients relative to normal controls is indicative of a sensory gating deficit and is one of the most robust findings reported for functional brain abnormalities in this disorder. However, there is considerable gating variability in patients and controls and there is little understanding as to how inter-individual differences moderate gating responses to drugs and nicotinic agonists in particular, which have shown potential to reverse gating deficits. In this study the effects of acutely administered nicotine (gum, 6 mg) on sensory gating in a paired (S₁-S₂) auditory stimulus paradigm were investigated in 57 healthy, non-smoking volunteers stratified as low (n = 19), medium (n = 19) and high (n = 19) P50 suppressors on the basis of three separate baseline derived gating indices, P50 ratios, P50 difference scores, and gating difference waveforms. Relative to placebo, nicotine consistently improved gating in low suppressors as stratified with all three gating indices, exerted no effects in medium suppressors and reduced gating in high suppressors. Analysis of individual stimulus (S₂, S₂) amplitudes showed distinctly different mechanisms of action underlying nicotine effects in individuals with low and high baseline suppression. The results parallel similar findings of baseline-dependency in the gating effects of several antipsychotic drugs in healthy volunteers and support the use of group segmentation as a translational model in novel cognitive drug development for schizophrenia.

Effects of nicotine on social cognition, social competence and self-reported stress in schizophrenia patients and healthy controls

More than 80 % of patients diagnosed with schizophrenia are nicotine-dependent. Self-medication of cognitive deficits and an increased vulnerability to stress are discussed as promoting factors for the development of nicotine dependence. However, the effects of nicotine on social cognition and subjective stress responses in schizophrenia are largely unexplored. A 2 × 2-factorial design (drug × group) was used to investigate the effects of nicotine versus placebo in smoking schizophrenia patients and healthy controls after 24 h of abstinence from smoking. Participants performed a facial affect recognition task and a semi-standardized role-play task, after which social competence and self-reported stress during social interaction were assessed. Data analysis revealed no significant group differences in the facial affect recognition task. During social interaction, healthy controls showed more non-verbal expressions and a lower subjective stress level than schizophrenia patients. There were no significant effects of nicotine in terms of an enhanced recognition of facial affect, more expressive behaviour or reduced subjective stress during social interaction. While schizophrenia patients unexpectedly recognized facial affect not significantly worse than healthy controls, the observed group differences in subjective stress and non-verbal expression during social interaction in the role-play situation are in line with previous findings. Contrary to expectations derived from the self-medication hypothesis, nicotine showed no significant effects on the dependent variables, perhaps because of the dosage used and the delay between the administration of nicotine and the performance of the role-play.

Comorbid substance use disorder in schizophrenia: a selective overview of neurobiological and cognitive underpinnings

Although individuals with schizophrenia show a lifetime prevalence of 50% for suffering from a comorbid substance use disorder, substance abuse usually represents an exclusion criterion for studies on schizophrenia. This implies that surprisingly little is known about a large group of patients who are particularly difficult to treat. The aim of the present work is to provide a brief and non-exhaustive overview of the current knowledgebase about neurobiological and cognitive underpinnings for dual diagnosis schizophrenia patients. Studies published within the last 20 years were considered using computerized search engines. The focus was on nicotine, caffeine, alcohol, cannabis and cocaine being among the most common substances of abuse. All drugs of abuse target dopaminergic, glutamatergic and GABAergic transmission which are also involved in the pathophysiology of schizophrenia. Current literature suggests that neurocognitive function might beless disrupted in substance-abusing compared to non-abusing schizophrenia patients, but in particular the neuroimaging database on this topic is sparse. Detrimental effects on brain structure and function were shown for patients for whom alcohol is the main substance of abuse. It is as yet unclear whether this finding might be an artifact of age differences of patient subgroups with different substance abuse patterns. More research is warranted on the specific neurocognitive underpinnings of schizophrenia patients abusing distinct psychoactive substances. Treatment programs might either benefit from preserved cognitive function as a resource or specifically target cognitive impairment in different subgroups of addicted schizophrenia patients.

Rivastigmine reverses cognitive deficit and acetylcholinesterase activity induced by ketamine in an animal model of schizophrenia

Schizophrenia is one of the most disabling mental disorders that affects up to 1 % of the population worldwide. Although the causes of this disorder remain unknown, it has been extensively characterized by a broad range of emotional, ideational and cognitive impairments. Studies indicate that schizophrenia affects neurotransmitters such as dopamine, glutamate and acetylcholine. Recent studies suggest that rivastigmine (an acetylcholinesterase inhibitor) is important to improve the cognitive symptoms of schizophrenia. Therefore, the present study evaluated the protective effect of rivastigmine against the ketamine-induced behavioral (hyperlocomotion and cognitive deficit) and biochemical (increase of acetylcholinesterase activity) changes which characterize an animal model of schizophrenia in rats. Our results indicated that rivastigmine was effective to improve the cognitive deficit in different task (immediate memory, long term memory and short term memory) induced by ketamine in rats. Moreover, we observed that rivastigmina reversed the increase of acetylcholinesterase activity induced by ketamine in the cerebral cortex, hippocampus and striatum. However, rivastigmine was not able to prevent the ketamine-induced hyperlocomotion. In conslusion, ours results indicate that cholinergic system might be an important therapeutic target in the physiopathology of schizophrenia, mainly in the cognition, but additional studies should be carried.

Investigation of cigarette smoking among male schizophrenia patients

Male schizophrenia patients are known to have a heavier smoking pattern compared with the general population. However, the mechanism for this association is not known, though hypothesis that smoking could alleviate symptomatology of schizophrenia and reduce side effects of antipsychotics has been suggested. The aims of this study were to validate the heavier smoking pattern among male schizophrenia patients and to investigate the possible mechanisms for the association. To enhance the reliability of the study, we recruited two large independent samples with 604 and 535 male Chinese schizophrenia patients, and compared their smoking pattern with that of 535 healthy male controls recruited from general population. Validated multiple indicators and multiple causes structure equation model and regression models were used to investigate the association of smoking with factors of schizophrenia symptomatology and with the usage of antipsychotics and their extra-pyramidal side effects (EPS). Schizophrenia patients had significantly heavier smoking pattern compared with healthy controls in our sample (42.4% vs. 16.8%, p<0.001 for current smoking prevalence; 23.5% vs. 43.3%, p<0.001 for smoking cessation rate; 24.5% vs. 3.0%, p<0.001 for heavy smoker proportion). Their smoking status was also found to be consistently and significantly associated with reduced negative factor scores for schizophrenia symptomatology (β = −0.123, p = 0.051 for sample-A; β = −0.103, p = 0.035 for sample-B; β = −0.082, p = 0.017 for the combined sample). However, no significant association was found between smoking and antipsychotics usage or risk of EPS. These results support that smoking is associated with improved negative symptoms, which could account for the heavier smoking pattern among schizophrenia patients.

Cigarette smoking, psychopathology and cognitive function in first-episode drug-naive patients with schizophrenia: a case-control study

BACKGROUND

Although patients with chronic schizophrenia have substantially higher smoking rates than either the general population or patients with other mental illnesses, drug-naive patients with a first episode of schizophrenia have received little systemic study. This study examined smoking rates, the association between smoking and symptom severity and cognitive function in Chinese first-episode schizophrenia (FES) patients using cross-sectional and case-control designs.

METHOD

Two hundred and forty-four drug-naive FES patients and 256 healthy controls matched for gender, age and education completed the Fagerström Test for Nicotine Dependence (FTND) and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Patients were also rated on the Positive and Negative Symptom Scale (PANSS).

RESULTS

The rate and quantity of smoking were not significantly higher among FES patients compared to the general population. Among patients, smokers scored higher than non-smokers on the total PANSS and the positive symptom subscale scores. There were no significant associations between cognitive function and smoking in either FES patients or healthy controls.

CONCLUSIONS

In contrast to studies in patients with chronic schizophrenia, drug-naive FES patients did not smoke more frequently than the general population. Furthermore, patients with psychotic disorders who smoked did not exhibit significant cognitive differences compared with those who did not smoke. However, smoking may have other detrimental effects on physical and mental health, for example on positive symptoms.

Nicotinic modulation of intrinsic brain networks in schizophrenia

The nicotinic receptor is a promising drug target currently being investigated for the treatment of cognitive symptoms in schizophrenia. A key step in this process is the development of noninvasive functional neuroimaging biomarkers that can be used to determine if nicotinic agents are eliciting their targeted biological effect, ideally through modulation of a fundamental aspect of neuronal function. To that end, neuroimaging researchers are beginning to understand how nicotinic modulation affects "intrinsic" brain networks to elicit potentially therapeutic effects. An intrinsic network is a functionally and (often) structurally connected network of brain areas whose activity reflects a fundamental neurobiological organizational principle of the brain. This review summarizes findings of the effects of nicotinic drugs on three topics related to intrinsic brain network activity: (1) the default mode network, a group of brain areas for which activity is maximal at rest and reduced during cognitive tasks, (2) the salience network, which integrates incoming sensory data with prior internal representations to guide future actions and change predictive values, and (3) multi-scale complex network dynamics, which describe these brain's ability to efficiency integrate information while preserving local functional specialization. These early findings can be used to inform future neuroimaging studies that examine the network effects of nicotinic agents.

MK-801 disrupts and nicotine augments 40 Hz auditory steady state responses in the auditory cortex of the urethane-anesthetized rat

Patients with schizophrenia show marked deficits in processing sensory inputs including a reduction in the generation and synchronization of 40 Hz gamma oscillations in response to steady-state auditory stimulation. Such deficits are not readily demonstrable at other input frequencies. Acute administration of NMDA antagonists to healthy human subjects or laboratory animals is known to reproduce many sensory and cognitive deficits seen in schizophrenia patients. In the following study, we tested the hypothesis that the NMDA antagonist MK-801 would selectively disrupt steady-state gamma entrainment in the auditory cortex of urethane-anesthetized rat. Moreover, we further hypothesized that nicotinic receptor activation would alleviate this disruption. Auditory steady state responses were recorded in response to auditory stimuli delivered over a range of frequencies (10-80 Hz) and averaged over 50 trials. Evoked power was computed under baseline condition and after vehicle or MK-801 (0.03 mg/kg, iv). MK-801 produced a significant attenuation in response to 40 Hz auditory stimuli while entrainment to other frequencies was not affected. Time-frequency analysis revealed deficits in both power and phase-locking to 40 Hz. Nicotine (0.1 mg/kg, iv) administered after MK-801 reversed the attenuation of the 40 Hz response. Administered alone, nicotine augmented 40 Hz steady state power and phase-locking. Nicotine's effects were blocked by simultaneous administration of the α4β2 antagonist DHßE. Thus we report for the first time, a rodent model that mimics a core neurophysiological deficit seen in patients with schizophrenia and a pharmacological approach to alleviate it.

Effects of risperidone, amisulpride and nicotine on eye movement control and their modulation by schizotypy

RATIONALE

The increasing demand to develop more efficient compounds to treat cognitive impairments in schizophrenia has led to the development of experimental model systems. One such model system combines the study of surrogate populations expressing high levels of schizotypy with oculomotor biomarkers.

OBJECTIVES

We aimed (1) to replicate oculomotor deficits in a psychometric schizotypy sample and (2) to investigate whether the expected deficits can be remedied by compounds shown to ameliorate impairments in schizophrenia.

METHODS

In this randomized double-blind, placebo-controlled study 233 healthy participants performed prosaccade (PS), antisaccade (AS) and smooth pursuit eye movement (SPEM) tasks after being randomly assigned to one of four drug groups (nicotine, risperidone, amisulpride, placebo). Participants were classified into medium- and high-schizotypy groups based on their scores on the Schizotypal Personality Questionnaire (SPQ, Raine (Schizophr Bull 17:555-564, 1991)).

RESULTS

AS error rate showed a main effect of Drug (p < 0.01), with nicotine improving performance, and a Drug by Schizotypy interaction (p = 0.04), indicating higher error rates in medium schizotypes (p = 0.01) but not high schizotypes under risperidone compared to placebo. High schizotypes had higher error rates than medium schizotypes under placebo (p = 0.03). There was a main effect of Drug for saccadic peak velocity and SPEM velocity gain (both p ≤ 0.01) indicating impaired performance with risperidone.

CONCLUSIONS

We replicate the observation of AS impairments in high schizotypy under placebo and show that nicotine enhances performance irrespective of group status. Caution should be exerted in applying this model as no beneficial effects of antipsychotics were seen in high schizotypes.

Granisetron as an add-on to risperidone for treatment of negative symptoms in patients with stable schizophrenia: randomized double-blind placebo-controlled study

Some 5-HT3 antagonists such as ondansetron have shown beneficial effects on negative symptoms of patients with schizophrenia. We aimed to evaluate the efficacy of granisetron (another 5-HT3 antagonist) add-on therapy in the treatment of negative symptoms of patients with stable schizophrenia. In a randomized, double-blind, and placebo-controlled study, forty stable patients with schizophrenia (DSM-IV-TR), were randomized to either granisetron (1 mg twice daily) or placebo (twice daily) in addition to risperidone up to 6 mg/day for eight weeks. The patients were assessed using positive and negative syndrome scale (PANSS) and extrapyramidal symptom rating scale (ESRS) at baseline, week 4 and 8. Hamilton depression rating scale (HDRS) was used to assess depression at baseline and week 8. Thirty-eight patients completed the trial. Granisetron group showed a significantly greater improvement on negative subscale than the placebo group at endpoint [t(38) = 6.046, mean difference (±95% CI) = 3.2(1.8-3.7), P < 0.001]. The same effect was observed for total score [t(38) = 4.168, mean difference (95% CI) = 3.2(1.6-4.7), P < 0.001]. However the placebo and granisetron groups did not differ in their reduction of positive and general psychopathology symptoms scores. HDRS scores and its changes did not differ between the two groups. The ESRS score at week 4 was significantly lower in the granisetron than the placebo group while the two groups showed similar ESRS score at week 8. Frequency of other side effects was similar between the two groups. In summary, granisetron add-on can safely and effectively reduce the primary negative symptoms of patients with schizophrenia.

Effects of COMT genotype on sensory gating and its modulation by nicotine: Differences in low and high P50 suppressors

Elevated smoking rates seen in schizophrenia populations may be an attempt to correct neuropathologies associated with deficient nicotinic acetylcholine receptors and/or dopaminergic systems using exogenous nicotine. However, nicotine's effects on cognitive processing and sensory gating have been shown to be baseline-dependent. Evidence of a restorative effect on sensory gating deficits by nicotine-like agonists has been demonstrated, however, its underlying mechanisms in the context of dopamine dysregulation are unclear. Catechol-O-methyltransferase (COMT), a key dopamine regulator in the brain, contains a co-dominant allele in which a valine-to-methionine substitution causes variations in enzymatic activity leading to reduced synaptic dopamine levels in the Val/Val genotype. Using a randomized, double-blind, placebo-controlled design with 57 non-smokers, this study examined the effects of COMT genotype on sensory gating and its modulation by nicotine in low vs. high suppressors. The results were consistent with the hypothesis that increased dopamine resulting from nicotine stimulation or Met allelic activity would benefit gating in low suppressors and impair gating in high suppressors, and that this gating improvement with nicotine would be more evident in Val carriers who were low suppressors, while the gating impairment would be more evident in Met carriers who were high suppressors. These findings reaffirm the importance of baseline-dependency and suggest a subtle relationship between COMT genotype and baseline-stratified levels of sensory gating, which may help to explain the variability of cognitive abilities in schizophrenia populations.

Persistent negative symptoms in first episode patients with schizophrenia: results from the European First Episode Schizophrenia Trial

Negative symptoms that do not improve following antipsychotic treatment represent a challenge for development of effective treatments. Few studies have been carried out so far, especially in first-episode schizophrenia patients, to clarify prevalence, correlates and impact of persistent negative symptoms (PNS) on short- and long-term outcome of the disease. All patients from EUFEST study for whom both baseline and 12-month assessments were available were included (N=345). PNS were defined as the presence of at least one negative symptom of moderate or higher severity, not confounded by depression or parkinsonism, at baseline and after 1 year of treatment. Patients with PNS were compared to those with at least one negative symptom of moderate or higher severity at the baseline, not persisting after 1 year, on demographic, clinical, neurocognitive, global functioning and quality of life measures. PNS not confounded by depression or parkinsonism were present in 6.7% of the sample. The symptom that more often persisted was blunted affect. Patients with PNS differed from those without PNS for a longer duration of untreated psychosis (DUP) and a more frequent discontinuation of study treatment; they also had a poorer psychopathological outcome and a worse global functioning after 1 year of treatment. The presence of PNS was associated to poorer improvement of all psychopathological dimensions and worse global functioning after 1 year of treatment. The longer DUP in subjects with PNS suggests that programs aimed at shortening DUP might reduce the prevalence of PNS and improve prognosis of schizophrenia.

Nicotinic agonist-induced improvement of vigilance in mice in the 5-choice continuous performance test

Impaired attentional processing is prevalent in numerous neuropsychiatric disorders and may negatively impact other cognitive and functional domains. Nicotine - a nonspecific nicotinic acetylcholine receptor (nAChR) agonist - improves vigilance in healthy subjects and schizophrenia patients as measured by continuous performance tests (CPTs), but the nAChR mediating this effect remains unclear. Here we examine the effects of: (a) nicotine; (b) the selective α7 nAChR agonist PNU 282987; and (c) the selective α4β2 nAChR agonist ABT-418 alone and in combination with scopolamine-induced disruption of mouse 5-choice (5C-)CPT performance. This task requires the inhibition of responses to non-target stimuli as well as active responses to target stimuli, consistent with human CPTs. C57BL/6N mice were trained to perform the 5C-CPT. Drug effects were examined in extended session and variable stimulus-duration challenges of performance. Acute drug effects on scopolamine-induced disruption in performance were also investigated. Nicotine and ABT-418 subtly but significantly improved performance of normal mice and attenuated scopolamine-induced disruptions in the 5C-CPT. PNU 282-987 had no effects on performance. The similarity of nicotine and ABT-418 effects provides support for an α4β2 nAChR mechanism of action for nicotine-induced improvement in attention/vigilance. Moreover, the data provide pharmacological predictive validation for the 5C-CPT because nicotine improved and scopolamine disrupted normal performance of the task, consistent with healthy humans in the CPT. Future studies using more selective agonists may result in more robust improvements in performance.

A diagnostic model incorporating P50 sensory gating and neuropsychological tests for schizophrenia

OBJECTIVES

Endophenotypes in schizophrenia research is a contemporary approach to studying this heterogeneous mental illness, and several candidate neurophysiological markers (e.g. P50 sensory gating) and neuropsychological tests (e.g. Continuous Performance Test (CPT) and Wisconsin Card Sorting Test (WCST)) have been proposed. However, the clinical utility of a single marker appears to be limited. In the present study, we aimed to construct a diagnostic model incorporating P50 sensory gating with other neuropsychological tests in order to improve the clinical utility.

METHODS

We recruited clinically stable outpatients meeting DSM-IV criteria of schizophrenia and age- and gender-matched healthy controls. Participants underwent P50 sensory gating experimental sessions and batteries of neuropsychological tests, including CPT, WCST and Wechsler Adult Intelligence Scale Third Edition (WAIS-III).

RESULTS

A total of 106 schizophrenia patients and 74 healthy controls were enrolled. Compared with healthy controls, the patient group had significantly a larger S2 amplitude, and thus poorer P50 gating ratio (gating ratio = S2/S1). In addition, schizophrenia patients had a poorer performance on neuropsychological tests. We then developed a diagnostic model by using multivariable logistic regression analysis to differentiate patients from healthy controls. The final model included the following covariates: abnormal P50 gating (defined as P50 gating ratio >0.4), three subscales derived from the WAIS-III (Arithmetic, Block Design, and Performance IQ), sensitivity index from CPT and smoking status. This model had an adequate accuracy (concordant percentage = 90.4%; c-statistic = 0.904; Hosmer-Lemeshow Goodness-of-Fit Test, p = 0.64>0.05).

CONCLUSION

To the best of our knowledge, this is the largest study to date using P50 sensory gating in subjects of Chinese ethnicity and the first to use P50 sensory gating along with other neuropsychological tests to develop a diagnostic model for schizophrenia. Further research to validate the predictive accuracy of this model by applying it on other samples is warranted.

Counseling and exercise intervention for smoking reduction in patients with schizophrenia: a feasibility study

Smoking cessation is possible for individuals with schizophrenia but the relapse rate is high. It is necessary to develop more flexible approaches to help these patients. The aim of this study was to examine the feasibility of an intervention approach that integrates counseling and exercise for participants with schizophrenia or schizoaffective disorder. A single group prospective design was used in this study. A sample of inpatients with schizophrenia or schizoaffective disorder participated in a program called "oxygen group", a program combining five sessions of smoking reduction counseling and three sessions of moderate intensity exercise over an 8-week period. Tobacco consumption, motivation, carbon monoxide level, anxiety and depression, smoking self-efficacy, nicotine dependence and waist circumference were measured pre- and post-intervention. Participants reported their satisfaction with the study characteristics after completion of the intervention. Smoking consumption and CO level were assessed at 6-week post-intervention follow-up. Twelve individuals (mean age 45.7±10.8years) were recruited. Participant attendance was 81.3%. There were no dropouts. Significant decreases were found for tobacco consumption (P=.04) and CO rate (P=.003) at the end of the intervention and were maintained at 6-week follow-up. Compared to baseline levels, there were no changes in depression and anxiety. Smoking cessation motivation increased significantly. This intervention appears feasible and acceptable to patients with schizophrenia and there were promising findings regarding smoking reduction. Larger trials to test the intervention are warranted.

Schizophrenia: a neurodevelopmental disorder--integrative genomic hypothesis and therapeutic implications from a transgenic mouse model

Schizophrenia is a neurodevelopmental disorder featuring complex aberrations in the structure, wiring, and chemistry of multiple neuronal systems. The abnormal developmental trajectory of the brain appears to be established during gestation, long before clinical symptoms of the disease appear in early adult life. Many genes are associated with schizophrenia, however, altered expression of no one gene has been shown to be present in a majority of schizophrenia patients. How does altered expression of such a variety of genes lead to the complex set of abnormalities observed in the schizophrenic brain? We hypothesize that the protein products of these genes converge on common neurodevelopmental pathways that affect the development of multiple neural circuits and neurotransmitter systems. One such neurodevelopmental pathway is Integrative Nuclear FGFR1 Signaling (INFS). INFS integrates diverse neurogenic signals that direct the postmitotic development of embryonic stem cells, neural progenitors and immature neurons, by direct gene reprogramming. Additionally, FGFR1 and its partner proteins link multiple upstream pathways in which schizophrenia-linked genes are known to function and interact directly with those genes. A th-fgfr1(tk-) transgenic mouse with impaired FGF receptor signaling establishes a number of important characteristics that mimic human schizophrenia - a neurodevelopmental origin, anatomical abnormalities at birth, a delayed onset of behavioral symptoms, deficits across multiple domains of the disorder and symptom improvement with typical and atypical antipsychotics, 5-HT antagonists, and nicotinic receptor agonists. Our research suggests that altered FGF receptor signaling plays a central role in the developmental abnormalities underlying schizophrenia and that nicotinic agonists are an effective class of compounds for the treatment of schizophrenia.

Allosteric alpha-7 nicotinic receptor modulation and P50 sensory gating in schizophrenia: a proof-of-mechanism study

In this multicenter, double-blind, placebo-controlled, randomized, four way cross-over proof-of-mechanism study, we tested the effect of the positive allosteric α7 nicotinic acetylcholine receptor (nAChR) modulator JNJ-39393406 in a key translational assay (sensory P50 gating) in 39 regularly smoking male patients with schizophrenia. All patients were clinically stable and JNJ-39393406 was administered as an adjunct treatment to antipsychotics. No indication was found that JNJ-39393406 has the potential to reverse basic deficits of information processing in schizophrenia (sensory P50 gating) or has a significant effect on other tested electrophysiological markers (MMN, P300 and quantitative resting EEG). Sensitivity analyses including severity of disease, baseline P50 gating, medication and gene variants of the CHRNA7 gene did not reveal any subgroups with consistent significant effects. It is discussed that potential positive effects in subgroups not present or not large enough in the current study or upon chronic dosing are possible, but unlikely to be developed. This article is part of a Special Issue entitled 'Cognitive Enhancers'.

Tobacco smoking in treatment-resistant schizophrenia patients is associated with impaired cognitive functioning, more severe negative symptoms, and poorer social adjustment

Tobacco smoking is common in schizophrenia patients. It has been reported that schizophrenia patients who are tobacco smokers have better cognitive performances compared to those who are nonsmokers. However, little is known on the effects of tobacco smoking in treatment-resistant schizophrenia (TRS) patients. The aim of this study was to compare cognitive performances, psychotic symptoms, and social adjustment in tobacco smoker TRS patients compared to nonsmoker TRS patients. Smoker and nonsmoker TRS patients did not differ in demographics and in mean daily antipsychotic dose. Smoker TRS patients had significantly higher scores than nonsmoker patients on the positive and negative syndrome scale (PANSS) and on the negative symptoms subscale. These patients also performed worse than nonsmoker patients on problem-solving cognitive domain. Social adjustment was not significantly different between the two groups. In both groups of patients, worse cognitive performances were mostly predicted by higher severity of negative symptoms. Worse performances on the verbal memory and problem-solving cognitive domains were correlated with social-functioning impairment in tobacco smoker TRS patients but not in nonsmoker ones. The results showed that tobacco smoking was not significantly associated with better cognitive performances in TRS patients, while it was significantly associated with higher negative symptoms. Even if a direct causative mechanism cannot be inferred and despite the fact that these patients may use tobacco to self-medicate, it could be speculated that these associations may, at least partially, be related to a tobacco-smoking-induced worsening of abnormal dopamine dysfunction, which has been suggested to occur in TRS patients.

Alpha7 neuronal nicotinic receptors as a drug target in schizophrenia

INTRODUCTION

Schizophrenia is a profoundly debilitating disease that represents not only an individual, but a societal problem. Once characterized solely by the hyperactivity of the dopaminergic system, therapies directed to dampen dopaminergic neurotransmission were developed. However, these drugs do not address the significant impairments in cognition and the negative symptoms of the disease, and it is now apparent that disequilibrium of many neurotransmitter systems is involved. Despite enormous efforts, minimal progress has been made toward the development of safer, more effective therapies to date.

AREAS COVERED

The high preponderance of smoking in schizophrenics suggests that nicotine may provide symptomatic improvement, which has led to investigation for selective molecules targeted to individual nicotinic receptor (nAChR) subtypes. Of special interest is activation of the homomeric α7nAChR, which is widely distributed in the brain and has been implicated in the pathophysiology of schizophrenia through numerous approaches.

EXPERT OPINION

Preclinical and clinical data suggest that neuronal α7nAChRs play an important role in cognitive functions. Moreover, some, but not all, early clinical trials conducted with α7nAChR agonists show cognitive benefits in schizophrenics. These encouraging results suggest that development of compounds targeting α7nAChRs will represent a valuable tool to mitigate symptoms associated with schizophrenia, and open new strategies for better pharmacological treatment of these patients.

Olfactory bulb volume in smokers

The study aimed to investigate the volume of the olfactory bulb in smokers. Specifically, we wanted to see whether environmental influences may exert a negative influence on OB structure. Twenty-one smokers and 59 non-smokers, matched for age and sex, underwent olfactory testing by means of the Sniffin' Sticks testing device (measurement of odor threshold and identification abilities). In addition, they underwent an MR scan with 2-mm-thick T2-weighted fast spin-echo images without interslice gap in the coronal plane covering the anterior and middle segments of the base of the skull. Olfactory function was not different between the 2 groups; however, olfactory bulb volumes were smaller in smokers than in non-smokers (p = 0.006). The deficit seen at the level of the OB did not correlate with the duration of smoking. The current data indicate that smoking may have a negative effect on the olfactory system before this becomes obvious in terms of a decreased olfactory function.

Nicotine effects on anterior cingulate cortex in schizophrenia and healthy smokers as revealed by EEG-informed fMRI

Nicotine can have beneficial effects on attention performance and corresponding brain function in both schizophrenia patients and healthy controls, but it remains controversial whether nicotine affects brain function differentially in patients vs. controls. The effects of nicotine on brain activity elicited by attention-requiring oddball-type tasks have not been studied in schizophrenia patients. In this study we sought to investigate the impact of nicotine on the p300 evoked potential component and corresponding fMRI (functional magnetic resonance imaging) activation measures in schizophrenia patients and controls. Applying a double-blind, placebo-controlled cross-over design, the effects of 1mg nasal nicotine on brain activity elicited by a visual oddball-type task in N=14 schizophrenia and N=15 control smokers were studied with simultaneous EEG-fMRI. EEG single trial amplitudes were used to inform the fMRI analysis. We found a nicotine-associated increase in P300-informed fMRI activation in schizophrenia patients and controls, mainly in the anterior cingulate and adjacent medial frontal cortex. No group differences in the response to nicotine were found. Remarkably, averaged EEG and fMRI activation measures considered in isolation were largely unaffected by nicotine. Taken together, the effects of nicotine on P300 amplitude-associated brain activation do not seem to be fundamentally different in schizophrenic smokers and healthy controls.

Nicotine dependence and illness severity in schizophrenia

BACKGROUND

Reasons for the increased prevalence of cigarette smoking in schizophrenia are unclear. Studies assessing clinical symptoms have sampled heterogeneous populations, with discrepant findings.

AIMS

To examine the relationship between clinical features, social adjustment and nicotine dependence in a geographically defined population of people with schizophrenia.

METHOD

Cross-sectional clinical study of 131 people with schizophrenia in Nithsdale, Scotland.

RESULTS

Smokers were younger, mostly males and three times more likely to be unemployed. Those with severe nicotine dependence had greater scores on the positive subscale of the Positive and Negative Syndrome Scale (PANSS), and were prescribed higher doses of antipsychotic. Those with mild-moderate dependence had greater scores on the PANSS negative subscale. Greater symptom severity was associated with poorer social adjustment. Psychopathology and social adjustment were similar in quitters and never-smokers.

CONCLUSIONS

Our findings indicate an association between nicotine dependence, clinical symptoms and social adjustment in schizophrenia. Although causal links cannot be inferred, identifying the relationship between nicotine dependence and psychopathology may have some value in the management of smoking in schizophrenia. Further longitudinal studies are required to explore this relationship.

Nicotine, Auditory Sensory Memory, and sustained Attention in a Human Ketamine Model of Schizophrenia: Moderating Influence of a Hallucinatory Trait

BACKGROUND

The procognitive actions of the nicotinic acetylcholine receptor (nAChR) agonist nicotine are believed, in part, to motivate the excessive cigarette smoking in schizophrenia, a disorder associated with deficits in multiple cognitive domains, including low-level auditory sensory processes and higher-order attention-dependent operations.

OBJECTIVES

As N-methyl-d-aspartate receptor (NMDAR) hypofunction has been shown to contribute to these cognitive impairments, the primary aims of this healthy volunteer study were to: (a) to shed light on the separate and interactive roles of nAChR and NMDAR systems in the modulation of auditory sensory memory (and sustained attention), as indexed by the auditory event-related brain potential - mismatch negativity (MMN), and (b) to examine how these effects are moderated by a predisposition to auditory hallucinations/delusions (HD).

METHODS

In a randomized, double-blind, placebo-controlled design involving a low intravenous dose of ketamine (0.04 mg/kg) and a 4 mg dose of nicotine gum, MMN, and performance on a rapid visual information processing (RVIP) task of sustained attention were examined in 24 healthy controls psychometrically stratified as being lower (L-HD, n = 12) or higher (H-HD) for HD propensity.

RESULTS

Ketamine significantly slowed MMN, and reduced MMN in H-HD, with amplitude attenuation being blocked by the co-administration of nicotine. Nicotine significantly enhanced response speed [reaction time (RT)] and accuracy (increased % hits and d' and reduced false alarms) on the RVIP, with improved performance accuracy being prevented when nicotine was administered with ketamine. Both % hits and d', as well as RT were poorer in H-HD (vs. L-HD) and while hit rate and d' was increased by nicotine in H-HD, RT was slowed by ketamine in L-HD.

CONCLUSIONS

Nicotine alleviated ketamine-induced sensory memory impairment and improved attention, particularly in individuals prone to HD.

Progressive muscle relaxation in persons with schizophrenia: a systematic review of randomized controlled trials

Objective:

The aim of this systematic review was to assess the effectiveness of progressive muscle relaxation on psychological distress and anxiety symptoms and on response/remission for people with schizophrenia.

Methods:

Randomized controlled trials were considered if they investigated progressive muscle relaxation in patients with schizophrenia. EMBASE, PsycINFO, PubMed, ISI Web of Science, CINAHL, PEDro and Cochrane Library were searched. The selection of studies, data extraction and quality assessment were performed independently by two reviewers.

Results:

Three randomized controlled trials involving 146 patients met the inclusion criteria. Progressive muscle relaxation can acutely reduce state anxiety and psychological distress and improve subjective well-being. No studies investigated the evidence for progressive muscle relaxation as an add-on treatment for general psychopathology and for positive or negative symptoms. Also, no studies assessed the value of progressive muscle relaxation in longer-term treatment and for relapse prevention. There were no data to draw any conclusions about progressive muscle relaxation in comparison with other treatment modalities. None of the studies encountered adverse events. Dose-response relationships could not be determined.

Conclusion:

Progressive muscle relaxation might be a useful add-on treatment to reduce state anxiety and psychological distress and improve subjective well-being in persons with schizophrenia.

Yoga in schizophrenia: a systematic review of randomised controlled trials

OBJECTIVE

The objective of this systematic review was to assess the effectiveness of yoga as a complementary treatment on general psychopathology, positive and negative symptoms and health-related quality of life (HRQL) for people with schizophrenia.

METHOD

Randomised controlled trials (RCTs) were considered whether they investigated a yoga intervention in patients with schizophrenia. The selection of studies, data extraction and quality assessment were performed independently by two reviewers.

RESULTS

Only three RCTs met the inclusion criteria. Lower Positive and Negative Syndrome Scale (PANSS) total scores and subscale scores for positive and negative symptoms were obtained after yoga compared with exercise or waiting list control conditions. In the same way, the physical, psychological, social and environmental HRQL as measured with the abbreviated version of the World Health Organization Quality of Life questionnaire (WHOQOL-BREF) increased more significantly after yoga than after exercise or waiting list control conditions. None of the RCTS encountered adverse events. Dose-response relationships could, however, not be determined.

CONCLUSION

Although the number of RCTs included in this review was limited, results indicated that yoga therapy can be an useful add-on treatment to reduce general psychopathology and positive and negative symptoms. In the same way, HRQL improved in those antipsychotic-stabilised patients with schizophrenia following yoga.

Clinical characteristics of heavy and non-heavy smokers with schizophrenia

Up to 50-90% of persons with schizophrenia smoke cigarettes. Limited data and theories suggest persons with schizophrenia may smoke for different reasons than persons without schizophrenia, making smoking cessation interventions particularly challenging in this population. Although health consequences of smoking are widely known, less information is available regarding characteristics of different amounts of smoking exposure in this population. This study was performed to investigate differences between heavy (≥ 1 pack per day) and non-heavy (<1 pack per day) smoking in patients with schizophrenia. Data from 745 patients, mean age 41.3+/-12.6 years, were drawn from a population of smokers admitted to State of Maryland inpatient mental health facilities (1994-2000). Records were reviewed to obtain demographic information, diagnosis, medication, smoking and substance use. 43% of patients were characterized as heavy smokers. Heavy and non-heavy groups did not differ in age, GAF, weight, or BMI. No differences were found in race, gender or antipsychotic treatments. However, patients smoking ≥ 1 packs per day were more likely to use other substances such as alcohol (χ(2)=6.67, df=1, p=0.01), cocaine (χ(2)=6.66, df=1, p=0.01), and other substances (χ(2)=9.95, df=1, p=0.003) compared to non-heavy smokers. No differences in cannabis or heroin use were found by smoking category. Controlling for age, race, sex and BMI, heavy smokers had higher total cholesterol (190.7(51.6)mg/dL) compared to non-heavy smokers (178.2 (43.0)mg/dL, p=0.03), but no differences were found in glucose or blood pressure. Heavy smoking may be a particular health risk in schizophrenia and significant efforts for smoking cessation or reduction are needed.

Modeling the outcome of structural disconnection on resting-state functional connectivity

A growing body of experimental evidence suggests that functional connectivity at rest is shaped by the underlying anatomical structure. Furthermore, the organizational properties of resting-state functional networks are thought to serve as the basis for an optimal cognitive integration. A disconnection at the structural level, as occurring in some brain diseases, would then lead to functional and presumably cognitive impairments. In this work, we propose a computational model to investigate the role of a structural disconnection (encompassing putative local/global and axonal/synaptic mechanisms) on the organizational properties of emergent functional networks. The brain's spontaneous neural activity and the corresponding hemodynamic response were simulated using a large-scale network model, consisting of local neural populations coupled through white matter fibers. For a certain coupling strength, simulations reproduced healthy resting-state functional connectivity with graph properties in the range of the ones reported experimentally. When the structural connectivity is decreased, either globally or locally, the resultant simulated functional connectivity exhibited a network reorganization characterized by an increase in hierarchy, efficiency and robustness, a decrease in small-worldness and clustering and a narrower degree distribution, in the same way as recently reported for schizophrenia patients. Theoretical results indicate that most disconnection-related neuropathologies should induce the same qualitative changes in resting-state brain activity.

Cigarette smoking and cognitive function in Chinese male schizophrenia: a case-control study

Schizophrenic patients have higher smoking rates than the general population. Studies show that smoking may be a form of self-medication in an attempt to alleviate cognitive deficits in schizophrenic patients of European background. This study examined the relationships between smoking and cognitive deficits in Chinese schizophrenic patients, which have previously received little systemic study. We recruited 580 male chronic patients meeting DSM-IV criteria for schizophrenia and 175 male control subjects who were matched on age and education. The subjects completed a detailed cigarette smoking questionnaire, the Fagerstrom Test for Nicotine Dependence (FTND), and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Patients also were rated on the Positive and Negative Symptom Scale (PANSS), the Simpson and Angus Extrapyramidal Symptom Rating Scale (SAES), and the Abnormal Involuntary Movement Scale (AIMS). All five RBANS subscales except for the Visuospatial/Constructional index showed significantly lower cognitive performance for schizophrenics than normal controls. The schizophrenic smokers scored lower than the schizophrenic non-smokers on the RBANS total score and the Visuospatial/Constructional and Immediate Memory indices. Similarly, the control smokers scored lower than the control non-smokers on the RBANS total score and the Immediate Memory index . Also, the schizophrenic smokers consistently performed the poorest on the cognitive domains of the RBANS. Among the schizophrenic patients, smokers displayed significantly fewer negative symptoms than non-smokers. Using multivariate regression analysis the following variables were independently associated with the RBANS total score: years of education, PANSS negative symptom score, age at schizophrenia onset, and number of hospitalizations. Our results show that smoking is associated with significant cognitive impairment in both schizophrenic patients and normal controls, but the smokers with schizophrenia had a reduced level of negative symptoms, suggesting that the benefits of smoking for those with schizophrenia may be limited to certain aspects of a given clinical phenotype.

Mouse models for studying genetic influences on factors determining smoking cessation success in humans

Humans differ in their ability to quit using addictive substances, including nicotine, the major psychoactive ingredient in tobacco. For tobacco smoking, a substantial body of evidence, largely derived from twin studies, indicates that approximately half of these individual differences in ability to quit are heritable genetic influences that likely overlap with those for other addictive substances. Both twin and molecular genetic studies support overlapping influences on nicotine addiction vulnerability and smoking cessation success, although there is little formal analysis of the twin data that support this important point. None of the current datasets provides clarity concerning which heritable factors might provide robust dimensions around which individuals differ in ability to quit smoking. One approach to this problem is to test mice with genetic variations in genes that contain human variants that alter quit success. This review considers which features of quit success should be included in a comprehensive approach to elucidate the genetics of quit success, and how those features may be modeled in mice.

Abnormal activity of the MAPK- and cAMP-associated signaling pathways in frontal cortical areas in postmortem brain in schizophrenia

Recent evidence suggests that schizophrenia may result from alterations of integration of signaling mediated by multiple neurotransmitter systems. Abnormalities of associated intracellular signaling pathways may contribute to the pathophysiology of schizophrenia. Proteins and phospho-proteins comprising mitogen activated protein kinase (MAPK) and 3'-5'-cyclic adenosine monophosphate (cAMP)-associated signaling pathways may be abnormally expressed in the anterior cingulate (ACC) and dorsolateral prefrontal cortex (DLPFC) in schizophrenia. Using western blot analysis we examined proteins of the MAPK- and cAMP-associated pathways in these two brain regions. Postmortem samples were used from a well-characterized collection of elderly patients with schizophrenia (ACC=36, DLPFC=35) and a comparison (ACC=33, DLPFC=31) group. Near-infrared intensity of IR-dye labeled secondary antisera bound to targeted proteins of the MAPK- and cAMP-associated signaling pathways was measured using LiCor Odyssey imaging system. We found decreased expression of Rap2, JNK1, JNK2, PSD-95, and decreased phosphorylation of JNK1/2 at T183/Y185 and PSD-95 at S295 in the ACC in schizophrenia. In the DLPFC, we found increased expression of Rack1, Fyn, Cdk5, and increased phosphorylation of PSD-95 at S295 and NR2B at Y1336. MAPK- and cAMP-associated molecules constitute ubiquitous intracellular signaling pathways that integrate extracellular stimuli, modify receptor expression and function, and regulate cell survival and neuroplasticity. These data suggest abnormal activity of the MAPK- and cAMP-associated pathways in frontal cortical areas in schizophrenia. These alterations may underlie the hypothesized hypoglutamatergic function in this illness. Together with previous findings, these data suggest that abnormalities of intracellular signaling pathways may contribute to the pathophysiology of schizophrenia.