Why do patients with schizophrenia smoke?

Alpha7 nicotinic acetylcholine receptor is a target in pharmacology and toxicology

Alpha7 nicotinic acetylcholine receptor (α7 nAChR) is an important part of the cholinergic nerve system in the brain. Moreover, it is associated with a cholinergic anti-inflammatory pathway in the termination of the parasympathetic nervous system. Antagonists of α7 nAChR are a wide group represented by conotoxin and bungarotoxin. Even Alzheimer's disease drug memantine acting as an antagonist in its side pathway belongs in this group. Agonists of α7 nAChR are suitable for treatment of multiple cognitive dysfunctions such as Alzheimer's disease or schizophrenia. Inflammation or even sepsis can be ameliorated by the agonistic acting compounds. Preparations RG3487, SEN34625/WYE-103914, SEN12333, ABT-107, Clozapine, GTS-21, CNI-1493, and AR-R17779 are representative examples of the novel compounds with affinity toward the α7 nAChR. Pharmacological, toxicological, and medicinal significance of α7 nAChR are discussed throughout this paper.

Effects of smoking history on selective attention in schizophrenia

Smoking prevalence is highly elevated in schizophrenia compared to the general population and to other psychiatric populations. Evidence suggests that smoking may lead to improvements of schizophrenia-associated attention deficits; however, large-scale studies on this important issue are scarce. We examined whether sustained, selective, and executive attention processes are differentially modulated by long-term nicotine consumption in 104 schizophrenia patients and 104 carefully matched healthy controls. A significant interaction of 'smoking status' × 'diagnostic group' was obtained for the domain of selective attention. Smoking was significantly associated with a detrimental conflict effect in controls, while the opposite effect was revealed for schizophrenia patients. Likewise, a positive correlation between a cumulative measure of nicotine consumption and conflict effect in controls and a negative correlation in patients were found. These results provide evidence for specific directional effects of smoking on conflict processing that critically dissociate with diagnosis. The data supports the self-medication hypothesis of smoking in schizophrenia and suggests selective attention as a specific cognitive domain targeted by nicotine consumption. A potential mechanistic model explaining these findings is discussed.

Systematic review of the benefits of physical therapy within a multidisciplinary care approach for people with schizophrenia

BACKGROUND

Although schizophrenia is the fifth leading cause of disability-adjusted life years worldwide in people aged 15 to 44 years, the clinical evidence of physical therapy as a complementary treatment remains largely unknown.

PURPOSE

The purpose of this study was to systematically review randomized controlled trials (RCTs) evaluating the effectiveness of physical therapy for people with schizophrenia.

DATA SOURCES

EMBASE, PsycINFO, PubMed, ISI Web of Science, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Physiotherapy Evidence Database (PEDro), and the Cochrane Library were searched from their inception until July 1, 2011, for relevant RCTs. In addition, manual search strategies were used.

STUDY SELECTION

Two reviewers independently determined study eligibility on the basis of inclusion criteria.

DATA EXTRACTION

Reviewers rated study quality and extracted information about study methods, design, intervention, and results.

DATA SYNTHESIS

Ten RCTs met all selection criteria; 6 of these studies addressed the use of aerobic and strength exercises. In 2 of these studies, yoga techniques also were investigated. Four studies addressed the use of progressive muscle relaxation. There is evidence that aerobic and strength exercises and yoga reduce psychiatric symptoms, state anxiety, and psychological distress and improve health-related quality of life, that aerobic exercise improves short-term memory, and that progressive muscle relaxation reduces state anxiety and psychological distress.

LIMITATIONS

The heterogeneity of the interventions and the small sample sizes of the included studies limit overall conclusions and highlight the need for further research.

CONCLUSIONS

Physical therapy offers added value in the multidisciplinary care of people with schizophrenia.

Varenicline as a smoking cessation aid in schizophrenia: effects on smoking behavior and reward sensitivity

RATIONALE

Smoking rates are up to five times higher in people with schizophrenia than in the general population, placing these individuals at high risk for smoking-related health problems. Varenicline, an α4β2 nicotinic acetylcholine receptor partial agonist, is a promising aid for smoking cessation in this population. To maximize treatment efficacy while minimizing risks, it is critical to identify reliable predictors of positive response to varenicline in smokers with schizophrenia.

OBJECTIVES

Negative symptoms of schizophrenia are related to dysfunctions in the brain reward system, are associated with nicotine dependence, and may be improved by nicotine or nicotinic receptor agonists, suggesting that smoking cessation may be especially difficult for patients with substantial negative symptoms. The purpose of the study was to evaluate negative symptoms as predictors of response to varenicline.

METHODS

Patients with schizophrenia (N = 53) completed a 12-week smoking cessation trial combining varenicline with cognitive behavioral therapy. Negative symptoms were assessed via the Scale for the Assessment of Negative Symptoms (Andreasen 1983). Outcomes included smoking abstinence as assessed by self-report and expired carbon monoxide. Change in performance on a probabilistic reward task was used as an index of change in reward sensitivity during treatment.

RESULTS

At week 12, 32 participants met criteria for 14-day point-prevalence abstinence. Patients with lower baseline symptoms of affective flattening (more typical affect) were more likely to achieve smoking abstinence and demonstrated larger increases in reward sensitivity during treatment.

CONCLUSIONS

These data suggest that affective flattening symptoms in smokers with schizophrenia may predict response to varenicline.

Spatiotemporal and frequency domain analysis of auditory paired stimuli processing in schizophrenia and bipolar disorder with psychosis

Individuals with schizophrenia (SZ) or bipolar disorder with psychosis (BPP) may share neurophysiological abnormalities as measured in auditory paired-stimuli paradigms with electroencephalography (EEG). Such investigations have been limited, however, by quantifying only event-related potential peaks and/or broad frequency bands at limited scalp locations without considering possible mediating factors (e.g., baseline differences). Results from 64-sensor EEG collected in 180 age- and gender-matched participants reveal (i) accentuated prestimulus gamma oscillations and (ii) reduced P2 amplitudes and theta/alpha oscillations to S1 among participants with both SZ and BPP. Conversely, (iii) N1s in those with SZ to S1 were reduced compared to healthy volunteers and those with BPP, whereas (iv) beta range oscillations 200-300 ms following S2 were accentuated in those with BPP but not those with SZ. Results reveal a pattern of both unique and shared neurophysiological phenotypes occurring within major psychotic diagnoses.

The German multi-centre study on smoking-related behavior-description of a population-based case-control study

Tobacco smoking is a major risk factor for most of the diseases leading in mortality. Nicotine dependence (ND), which sustains regular smoking, is now acknowledged to be under substantial genetic control with some environmental contribution. At present, however, genetic studies on ND are mostly conducted in populations that have been poorly characterized with regard to ND-related phenotypes for the simple reason that the respective populations were not primarily collected to study ND. The German multi-centre study 'Genetics of Nicotine Dependence and Neurobiological Phenotypes', which is funded by the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) as part of the Priority Program (Schwerpunktprogramm) SPP1226: 'Nicotine-Molecular and Physiological Effects in CNS', was intended to overcome some of these inherent problems of current genetic studies of ND. The multi-centre study is a population-based case-control study of smokers and never-smokers (n = 2396). The study was unique worldwide because it was the first large-scale genetic study specifically addressing ND with the collection of a wide range of environmental, psychosocial and neurobiological phenotypes. Study design and major population characteristics with emphasis on risk prediction of smoking status were presented in this paper.

Anxiety, depression and methods of stress coping in patients with nicotine dependence syndrome

BACKGROUND

Nicotinism is the most common addiction in Poland. Nicotine dependence is the cause of numerous behavioral diseases, including ischemic heart disease, neoplasms and chronic obstructive pulmonary disease. A question arises whether a tendency to anxiety and depressive reactions, as well as the strategies of coping with stressful situations, is involved in the clinical presentation of this addiction.

MATERIAL/METHODS

The study was conducted in a group of 88 nicotine addicts without serious systemic comorbidities and in 84 healthy subjects. All the participants were assessed with Beck Depression Inventory (BDI), Spielberger State-Trait Anxiety Inventory (STAI) and the Coping Inventory for Stressful Situations (CISS).

RESULTS

The mean intensity of anxiety as a trait and anxiety as a state, as well as its level, were found to differ between the groups (Sten 6.28±1.52 and 4.86±1.05, p=0,0000 for the trait, and 6.09±1.25 and 4.92±1.29, p=0.0000, for the state, respectively). Similarly, depression was demonstrated to be more intensive in nicotine addicts than in healthy subjects (12.76 points ±4.77 vs. 10.76±4.83, p=0.007). Among the 5 scales assessed by CISS, smokers demonstrated higher prevalence of emotion-oriented coping than controls (standard 9 6.27±1.70 in smokers vs. 5.67±1.57, p=0.019) and involvement in distracting activities (5.84±1.48 vs. 5.28±1.46, p=0.014).

CONCLUSIONS

The obtained results indicate that anxiety and depression, as well as differences in coping with stress situations, distinguish nicotine addicts from non-smokers.

P50 sensory gating and smoking in the general population

P50 gating is a major functional biomarker in research on schizophrenia and other psychiatric conditions with high smoking prevalence. It is used as endophenotype for studying nicotinic systems genetics and as surrogate endpoint measure for drug development of nicotinic agonists. Surprisingly, little is known about P50 gating in the general population and the relationship to smoking-related characteristics. In this multicenter study at six academic institutions throughout Germany, n=907 never-smokers (NS<20 cigarettes/lifetime), n=463 light smokers (LS) with Fagerström Test for Nicotine Dependence (FTND)≥4 and n=353 heavy smokers (HS, FTND<4) were randomly selected from the general population. As part of a standardized protocol for investigating the genetics of nicotine dependence (ND), an auditory P50 paradigm was applied. The main outcome measure was P50-amplitude difference followed by time-frequency analyses and functional imaging (sLORETA). Reduced P50 gating was found in HS compared to NS with LS taking an intermediate position-correlating with the degree of ND. sLORETA and time-frequency analyses indicate that high-frequency oscillations in frontal brain regions are particularly affected. With growing age, P50 gating increased in (heavy) smokers. This is the first large-scale study (normative sample data) on P50 sensory gating and smoking in the general population. Diminished gating of P50 and associated high-frequency oscillations in the frontal brain region are indications of a deficient inhibitory cortical function in nicotine-dependent smokers. The suitability and application of sensory P50 gating as functional biomarker with regard to genetic and pharmacological studies is discussed.

Evidence-based guidelines for the pharmacological treatment of schizophrenia: recommendations from the British Association for Psychopharmacology

These guidelines from the British Association for Psychopharmacology address the scope and targets of pharmacological treatment for schizophrenia. A consensus meeting, involving experts in schizophrenia and its treatment, reviewed key areas and considered the strength of evidence and clinical implications. The guidelines were drawn up after extensive feedback from the participants and interested parties, and cover the pharmacological management and treatment of schizophrenia across the various stages of the illness, including first-episode, relapse prevention, and illness that has proved refractory to standard treatment. The practice recommendations presented are based on the available evidence to date, and seek to clarify which interventions are of proven benefit. It is hoped that the recommendations will help to inform clinical decision making for practitioners, and perhaps also serve as a source of information for patients and carers. They are accompanied by a more detailed qualitative review of the available evidence. The strength of supporting evidence for each recommendation is rated.

Tobacco craving in smokers with and without schizophrenia

We examined tobacco craving and dependence in current smokers (18-65 years) with schizophrenia (N=100) and those without a psychiatric disorder (normal controls, N=100). During the 2-3h visit participants completed demographic and smoking-related questionnaires and provided a breath CO sample. The Tobacco Craving Questionnaire-Short Form (TCQ-SF) was administered. Immediately after smoking one cigarette, no difference in TCQ-SF total score was noted (46.7±19.5 schizophrenia, 42.8±18.2 controls, p=0.15); however, after 15 min TCQ-SF total score was significantly higher in people with schizophrenia (50.0±19.6) than in controls (38.6±19.4) (p=0.0014). TCQ-SF factors of emotionality (p=0.0015), compulsivity (p=0.0003) and purposefulness (p=0.0174) were significantly greater in the schizophrenia group than the control group. FTND scores (5.5±2.0 vs 5.3±2.0, p=0.62) number of cigarettes smoked daily (17.9±11.6 vs. 17.0±7.9), expired breath CO (28.0±14.5 ppm vs. 22.0±8.0 ppm) and age at smoking initiation (16.2±5.4 vs. 15.6±5.5 years, p=0.44) did not differ in the schizophrenia and control groups respectively. In conclusion, tobacco craving as measured by the TCQ-SF was significantly greater in people with schizophrenia than controls 15 min post-smoking, despite similar scores in dependence and similar smoking histories and current smoking patterns.

Effects of progressive muscle relaxation on state anxiety and subjective well-being in people with schizophrenia: a randomized controlled trial

Objective: To examine the efficacy of a single progressive muscle relaxation session compared with a control condition on state anxiety, psychological stress, fatigue and subjective well-being in patients with schizophrenia.

Design: Randomized controlled trial.

Setting: An acute inpatient care unit of an University Psychiatric Centre.

Subjects: Sixty-four out of 88 eligible patients with schizophrenia.

Interventions: Patients were randomly assigned to either a single progressive muscle relaxation session during 25 minutes or a resting control condition with the opportunity to read for an equal amount of time.

Main outcome measures: Before and after the single interventions the State anxiety inventory and the Subjective exercise experiences scale were completed. Effect sizes were calculated.

Results: Only within progressive muscle relaxation, participants (n=27) showed decreased state anxiety, psychological stress and fatigue and increased subjective well-being. Between-group differences in post scores were found for state anxiety, subjective well-being and psychological stress, but not for fatigue. The effect size favouring progressive muscle relaxation was 1.26 for subjective well-being and −1.25 and −1.02 for respectively state anxiety and psychological stress.

Conclusions: Progressive muscle relaxation is highly effective in reducing acute feelings of stress and anxiety in patients with schizophrenia. A reduction in stress and state anxiety is associated with an increase in subjective well-being.

Nicotinic receptor gene CHRNA4 interacts with processing load in attention

BACKGROUND

Pharmacological studies suggest that cholinergic neurotransmission mediates increases in attentional effort in response to high processing load during attention demanding tasks [1].

METHODOLOGY/PRINCIPAL FINDINGS

In the present study we tested whether individual variation in CHRNA4, a gene coding for a subcomponent in α4β2 nicotinic receptors in the human brain, interacted with processing load in multiple-object tracking (MOT) and visual search (VS). We hypothesized that the impact of genotype would increase with greater processing load in the MOT task. Similarly, we predicted that genotype would influence performance under high but not low load in the VS task. Two hundred and two healthy persons (age range  =  39-77, Mean  =  57.5, SD  =  9.4) performed the MOT task in which twelve identical circular objects moved about the display in an independent and unpredictable manner. Two to six objects were designated as targets and the remaining objects were distracters. The same observers also performed a visual search for a target letter (i.e. X or Z) presented together with five non-targets while ignoring centrally presented distracters (i.e. X, Z, or L). Targets differed from non-targets by a unique feature in the low load condition, whereas they shared features in the high load condition. CHRNA4 genotype interacted with processing load in both tasks. Homozygotes for the T allele (N  =  62) had better tracking capacity in the MOT task and identified targets faster in the high load trials of the VS task.

CONCLUSION

The results support the hypothesis that the cholinergic system modulates attentional effort, and that common genetic variation can be used to study the molecular biology of cognition.

Cardiovascular aspects of antipsychotics

PURPOSE OF REVIEW

Schizophrenia is associated with increased mortality and reduced life expectancy, with cardiovascular disease being the most frequent cause of death. Antipsychotics have detrimental effects on different risk factors for cardiovascular disease. This review will focus on the relationship between antipsychotic treatment and cardiovascular disease.

RECENT FINDINGS

The increased overall mortality and mortality from cardiovascular disease in schizophrenia are now well documented. Patients with schizophrenia are at risk of receiving less optimal treatment for cardiovascular disease. Patients with schizophrenia are at high risk of metabolic syndrome, a cluster of risk factors for cardiovascular disease. Some antipsychotics, in particular, clozapine and olanzapine, frequently cause weight gain, dyslipidemia and diabetes mellitus. Antipsychotics differ in their effects on body weight, lipids and glucose regulation. However, the long-term effects of these differences between individual antipsychotics on overall mortality and cardiovascular mortality are not well established.

SUMMARY

More research is needed to better understand the relationship between schizophrenia, antipsychotic treatment and cardiovascular disease. More effective treatment strategies need to be developed to reduce the burden of cardiovascular disease in schizophrenia.

Nicotine dependence and serum BDNF levels in male patients with schizophrenia

OBJECTIVE

Schizophrenia is associated with a significantly high prevalence of smoking. Upregulation of neurotrophins by nicotine is well established. Accumulating evidence shows that brain-derived neurotrophic factor (BDNF) may be involved in the pathophysiology of schizophrenia. The purposes of this study were to compare BDNF levels in smokers to nonsmokers with schizophrenia and examine the association between BDNF levels and psychopathological symptoms.

MATERIALS AND METHODS

Serum BDNF levels were measured in 139 male inpatients with DSM-IV schizophrenia: 102 smokers and 37 nonsmokers. Symptoms were assessed with the Positive and Negative Syndrome Scale (PANSS).

RESULTS

The positive PANSS symptoms were lower in smokers than in nonsmokers, while the negative symptoms were lower in those who smoked more cigarettes. BDNF levels were significantly higher in smokers than in nonsmokers (p < 0.05). Higher BDNF levels correlated with fewer negative symptoms and with smoking more cigarettes.

CONCLUSION

The fewer positive symptoms in smokers and fewer negative symptoms in those who smoked more cigarettes may be associated with nicotine-induced upregulation of BDNF.

The role of nicotinic acetylcholine receptors in the medial prefrontal cortex and hippocampus in trace fear conditioning

Acute nicotine enhances multiple types of learning including trace fear conditioning but the underlying neural substrates of these effects are not well understood. Trace fear conditioning critically involves the medial prefrontal cortex and hippocampus, which both express nicotinic acetylcholine receptors (nAChRs). Therefore, nicotine could act in either or both areas to enhance trace fear conditioning. To identify the underlying neural areas and nAChR subtypes, we examined the effects of infusion of nicotine, or nicotinic antagonists dihydro-beta-erythroidine (DHβE: high-affinity nAChRs) or methyllycaconitine (MLA: low-affinity nAChRs) into the dorsal hippocampus, ventral hippocampus, and medial prefrontal cortex (mPFC) on trace and contextual fear conditioning. We found that the effects of nicotine on trace and contextual fear conditioning vary by brain region and nAChR subtype. The dorsal hippocampus was involved in the effects of nicotine on both trace and contextual fear conditioning but each task was sensitive to different doses of nicotine. Additionally, dorsal hippocampal infusion of the antagonist DHβE produced deficits in trace but not contextual fear conditioning. Nicotine infusion into the ventral hippocampus produced deficits in both trace and contextual fear conditioning. In the mPFC, nicotine enhanced trace but not contextual fear conditioning. Interestingly, infusion of the antagonists MLA or DHβE in the mPFC also enhanced trace fear conditioning. These findings suggest that nicotine acts on different substrates to enhance trace versus contextual fear conditioning, and that nicotine-induced desensitization of nAChRs in the mPFC may contribute to the effects of nicotine on trace fear conditioning.