Nicotine consumption and schizotypy in first-degree relatives of individuals with schizophrenia and non-psychiatric controls

The Association Between Chronic Tobacco Smoking and Brain Alterations in Schizophrenia: A Systematic Review of Magnetic Resonance Imaging Studies

BACKGROUND AND HYPOTHESIS

The high co-occurrence of tobacco smoking in patients with schizophrenia spectrum disorders (SSD) poses a serious health concern, linked to increased mortality and worse clinical outcomes. The mechanisms underlying this co-occurrence are not fully understood.

STUDY DESIGN

Addressing the need for a comprehensive overview of the impact of tobacco use on SSD neurobiology, we conducted a systematic review of neuroimaging studies (including structural, functional, and neurochemical magnetic resonance imaging studies) that investigate the association between chronic tobacco smoking and brain alterations in patients with SSD.

STUDY RESULTS

Eight structural and fourteen functional studies were included. Structural studies show widespread independent and additive reductions in gray matter in relation to smoking and SSD. The majority of functional studies suggest that smoking might be associated with improvements in connectivity deficits linked to SSD. However, the limited number of and high amount of cross-sectional studies, and high between-studies sample overlap prevent a conclusive determination of the nature and extent of the impact of smoking on brain functioning in patients with SSD. Overall, functional results imply a distinct neurobiological mechanism for tobacco addiction in patients with SSD, possibly attributed to differences at the nicotinic acetylcholine receptor level.

CONCLUSIONS

Our findings highlight the need for more longitudinal and exposure-dependent studies to differentiate between inherent neurobiological differences and the (long-term) effects of smoking in SSD, and to unravel the complex interaction between smoking and schizophrenia at various disease stages. This could inform more effective strategies addressing smoking susceptibility in SSD, potentially improving clinical outcomes.

Schizotypal dimensions are associated with current but not former tobacco consumption

OBJECTIVES

We aimed to study the relationship between tobacco smoking and attenuated psychosis measures taking into account several aspects of tobacco consumption that to date have not been explored and that could help understand this association, such as age of onset, the influence of former consumption and the duration of abstinence.

METHODS

We investigated, in a sample of 580 students, the relationship between schizotypy (using the schizotypal personality questionnaire-brief in a Likert format) and smoking status, nicotine dependence (measured with the Fagerström test for nicotine dependence), age of onset of smoking and in former smokers, duration of smoking abstinence.

RESULTS

35.2% of the students were current smokers and 13.4% were former smokers. We found that current but not former smokers had higher scores of schizotypy (total, positive and disorganized) than non-smokers. We found no association between schizotypy scores and nicotine dependence or earlier age of onset of smoking. The duration of smoking abstinence, in former smokers, was inversely correlated to the score of positive and total schizotypy.

CONCLUSIONS

Our results suggest that tobacco has a reversible effect on schizotypy, but more studies with a different design (controlled, longitudinal) and a more thorough exploration of potential confounders (e.g. cannabis) are needed before a firm conclusion can be reached.

Telehealth Implementation, Treatment Attendance, and Socioeconomic Disparities in Treatment Utilization in a Community Mental Health Setting During the COVID-19 Pandemic: A Retrospective Analysis of Electronic Health Record Data

Background

Previous studies have found that the widespread implementation of telehealth for outpatient mental health treatment during the COVID-19 pandemic has been associated with reduced no-show rates and increases in total number of appointments. However, it is unclear to what degree this is due to increased accessibility provided by telehealth, rather than to increased consumer demand for services fueled by the pandemic-related exacerbation of mental health needs. To shed light on this question, the present analysis examined changes in attendance rates for outpatient, home-, and school-based programs at a community mental health center in southeastern Michigan. Disparities in treatment utilization associated with socioeconomic status were also examined.

Methods

Two-proportion z-tests were conducted to examine changes in attendance rates, and Pearson correlations were calculated using the median income level and attendance rate by zip code to examine disparities in utilization associated with socioeconomic status.

Results

The proportion of appointments kept after telehealth implementation was statistically significantly higher for all outpatient programs, but not for any home-based programs. Specifically, absolute increases in the proportion of appointments kept ranged from 0.05 to 0.18 for outpatient programs, representing relative increases of 9.2% to 30.2%. Furthermore, before telehealth implementation, there was a strong positive correlation between income and attendance rate for all outpatient programs (ranging from r = 0.50 to 0.56). After telehealth implementation, there were no longer any significant correlations.

Discussion

Results highlight the utility of telehealth in increasing treatment attendance and mitigating disparities in treatment utilization associated with socioeconomic status. These findings are highly relevant to ongoing discussions surrounding the long-term fate of evolving insurance and regulatory guidelines pertaining to telehealth.

Moderating effect of schizotypy on the relationship between smoking and neurocognition

Purpose

Smoking rates in schizotypic individuals are shown to be elevated, as in patients with schizophrenia, although findings on the association of smoking with different symptomatology of schizotypy have been mixed. Moreover, possible moderating effects of schizotypy on the relationship between smoking and cognition have not been well documented.

Subjects and methods

The Schizotypal Personality Questionnaire (SPQ) and the full version of the Wechsler Memory Scale-Revised (WMS-R) were administered to 501 healthy adults. Subjects were divided into smokers (n = 85) and non-smokers (n = 416) based on the presence/absence of current smoking.

Results

The analysis of covariance (ANCOVA) on the three factor scores as well as the total score of the SPQ, controlling for age and gender, revealed that cognitive-perceptual factor was significantly associated with an increased rate of smoking (P = 0.048). The ANCOVA on the WMS-R indices, with smoking group as a fixed factor and age, gender and total SPQ score as covariates, revealed that the schizotypy-by-smoking interaction was significant for attention/working memory (P = 0.029).

Discussion and conclusion

Positive schizotypy may be associated with more smoking. Schizotypy and smoking could interact with each other to negatively affect attention/working memory.

Tobacco smoking and schizophrenia: re-examining the evidence

Tobacco smoking among people with mental illnesses can be explained by biological, psychological and social factors. The prevalence of smoking in people diagnosed with schizophrenia is higher than in people with other mental disorders and in the general population. This article explores three current hypotheses that explain this higher prevalence of smoking in schizophrenia. The first, the self-medication hypothesis, is increasingly countered by a growing body of evidence indicating that smokers experience more severe symptoms of schizophrenia. Numerous researchers have already identified smoking as a possible risk factor for the development of schizophrenia, which is the second hypothesis. The third hypothesis (shared genetic vulnerability) identifies certain genes that confer vulnerability for both schizophrenia and nicotine dependence. Understanding the reasons behind the higher prevalence of smoking among people with schizophrenia is vital in planning effective primary, secondary and tertiary smoking prevention for these individuals.

LEARNING OBJECTIVES

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Association of the manganese superoxide dismutase gene Ala-9Val polymorphism with age of smoking initiation in male schizophrenia smokers

Schizophrenia patients exhibit higher smoking rates than the general population. A growing body of evidence suggests that cigarette smoke impairs the antioxidant defense mechanisms, leading to oxidative damage. Manganese superoxide dismutase (MnSOD) is the major antioxidant in the mitochondria, catalyzing the metabolism of superoxide radicals to form hydrogen peroxide. Since the identification of a well-characterized functional polymorphism, Ala-9Val of MnSOD, a number of studies have evaluated the association between Val-9Ala and schizophrenia or cancer. In this study, we hypothesized that the functional polymorphism of MnSOD Ala-9Val was associated with smoking in patients with schizophrenia. This polymorphism was genotyped in 666 chronic male schizophrenia patients (smoker/never-smoker = 507/159) and 660 male controls (smoker/never-smoker = 360/300) using a case-control design. The cigarettes smoked per day (CPD) and smoking behaviors were evaluated by clinician-administered questionnaires and the Fagerstrom Test for Nicotine Dependence (FTND). The results showed no significant differences in MnSOD Ala-9Val genotype and allele distributions between the patients and healthy controls or between smokers and never-smokers in either patients or healthy controls alone. The smokers with the Ala allele started smoking significantly earlier (19.9 ± 5.8 vs. 21.7 ± 6.5 years, P = 0.005) only in patients. These results suggest that the MnSOD Ala-9Val polymorphism may not influence smoking status in a Chinese male schizophrenia population, but may influence the age at which smoking is started among schizophrenia smokers.

Does chronic nicotine consumption influence visual backward masking in schizophrenia and schizotypy?

Nicotine consumption is higher for people within the schizophrenia spectrum compared to controls. This observation supports the self-medication hypothesis, that nicotine relieves symptoms in, for example, schizophrenia patients. We tested whether performance in an endophenotype of schizophrenia (visual backward masking, VBM) is modulated by nicotine consumption in i) smoking and non-smoking schizophrenia patients, their first-degree relatives, and age-matched controls, ii) non-smoking and smoking university students, and iii) non-smoking, early and late onset nicotine smokers. Overall, our results confirmed that VBM deficits are an endophenotype of schizophrenia, i.e., deficits were highest in patients, followed by their relatives, students scoring high in Cognitive Disorganisation, and controls. Moreover, we found i) beneficial effects of chronic nicotine consumption on VBM performance, in particular with increasing age, and ii) little impact of clinical status alone or in interaction with nicotine consumption on VBM performance. Given the younger age of undergraduate students (up to 30 years) versus controls and patients (up to 66 years), we propose that age-dependent VBM deficits emerge when schizotypy effects are targeted in populations of a larger age range, but that nicotine consumption might counteract these deficits (supporting the self-medication hypothesis).

Altered time-perception performance in individuals with high schizotypy levels

The possibility of altered time-perception in high schizotypy scorers, as postulated through previous differences shown in performance between high and low scorers in schizotypy on schedules of reinforcement with temporal elements, was examined using a series of retrospective timing tasks. Three stimuli ratio manipulations were made across two experiments, and, using an adjusted version of the bisection-point method for data analysis, results showed that high scorers on the Unusual Experiences subscale of the O-LIFE(B) estimated the mid point of the stimulus range to be at a significantly longer interval than low scorers. This was true when the ratios between "short" and "long" standard stimuli were 4:1 (Experiment 1), 3:1 and 2:1 (Experiment 2). These findings are consistent with the notion of altered time-perception for high schizotypals.

Smoking topography and outcome expectancies among individuals with schizotypy

Compared to smokers in the general population, smokers with schizophrenia smoke more cigarettes per day and have higher nicotine dependence and biochemical indicators of nicotine intake. They also have more intense smoking topography and greater positive smoking expectancies. Little is known about the relationship between smoking and schizotypy, defined as the personality organization reflecting a vulnerability to schizophrenia-spectrum pathology. This study assessed schizotypy symptoms, smoking characteristics and behaviors, and smoking expectancies in young adults with psychometrically defined schizotypy and demographically matched controls without schizotypy. Smokers with schizotypy had higher nicotine dependence and smoked more cigarettes per week compared to control smokers. They were also more likely to endorse greater positive consequences (i.e., improved state enhancement, stimulation, social facilitation, taste/sensorimotor manipulation, reduced negative affect and boredom) and fewer negative consequences of smoking. Smokers with schizotypy and control smokers did not differ on smoking topography or carbon monoxide levels. This is the first known study to investigate relationships between these smoking-related variables in smokers with schizotypy. Individuals with schizotypy possessed certain smoking-related characteristics and smoking expectancies similar to those with schizophrenia. This offers preliminary insight into unique smoking-related factors among individuals with schizotypy and highlights the importance of continued research in this area.

Exploring the relationships between tobacco smoking and schizophrenia in first-degree relatives

Up to 90% of individuals with schizophrenia suffer from nicotine dependence. Both schizophrenia and nicotine consumption have strong genetic components, which may overlap. The relationship between schizophrenia and nicotine dependence remains unclear, due in part to confounding factors. Studies of the relationship between nicotine consumption and milder schizophrenia-related phenotypes, such as schizotypy, in first-degree relatives of individuals with schizophrenia could help to better understand the relationship between smoking and schizophrenia while avoiding such confounders. We assessed the proportion of smokers, their level of nicotine dependence and their level of schizotypy in a sample of 98 first-degree relatives of schizophrenic subjects and 110 healthy controls. Partial correlation analysis was used to assess the relationship between schizotypal dimensions and smoking dependence. The prevalence of smoking and nicotine dependence levels were higher in the relatives than in the healthy control group. We found no relationship between nicotine dependence and the magnitude of schizotypal features in either group. Our results support the hypothesis that the relationship between schizophrenia and smoking is largely mediated by common familial factors, which may be genetic.

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.

A validation of cognitive biomarkers for the early identification of cognitive enhancing agents in schizotypy: a three-center double-blind placebo-controlled study

A number of compounds aimed at improving cognition in schizophrenia have failed to demonstrate efficacy in Phase 2 clinical trials. Translational studies using biomarkers in surrogate populations, such as schizotypy, could be used to assess the efficacy of novel compounds. In this study, we aimed to validate the sensitivity and inter-site reliability of cognitive biomarkers (working memory (N-back), spatial working memory (SWM) and verbal fluency (VF) tasks) to detect the schizotypy phenotype and its reversal by psychotropic drugs. Healthy volunteers scoring high or average on a schizotypal personality measure (122 in each group) were randomized to receive a single dose of risperidone, amisulpride, nicotine or placebo in a double-blind, between-subject design. We found evidence for a poorer performance on N-back and VF tasks in the high schizotypy group, replicating previous research. This effect was counteracted by amisulpride on N-back: it improved working memory in high schizotypy group but impaired the controls. A similar pattern was seen in SWM and VF. We interpret this finding in the light of the dopamine enhancing action of amisulpride when given in low doses. In contrast, risperidone impaired both groups and nicotine had a beneficial effect for the low baseline performers only. These effects were consistent across sites. These data demonstrates the utility of biomarkers in detecting the effect of schizotypy and its reversal by drugs that enhance dopamine and cholinergic function. Studies using similar design could help the early assessment of potential of compounds designed to improve cognition in schizophrenia.

Stressing schizotypy: the modulating role of stress-relieving behaviours and intellectual capacity on functional hemispheric asymmetry

Relative cognitive impairments are common along the schizophrenia spectrum reflecting potential psychopathological markers. Yet stress, a vulnerability marker in schizophrenia (including its spectrum), is likewise related to cognitive impairments. We investigated whether one such cognitive marker (attenuated functional hemispheric asymmetry) during stressful life periods might be linked to individuals' schizotypal features or rather to individuals' stress-related experiences and behaviours. A total of 58 students performed a left hemisphere dominant (lateralised lexical decisions) and right hemisphere dominant (sex decisions on composite faces) task. In order to account for individual differences in stress sensitivity we separated participants into groups of high or low cognitive reserve according to their average current marks. In addition, participants filled in questionnaires on schizotypy (short O-LIFE), perceived stress, stress response, and a newly adapted questionnaire that enquired about potential stress compensation behaviour (elevated substance use). The most important finding was that enhanced substance use and cognitive disorganisation contributed to a right and left hemisphere shift in language dominance, respectively. We discuss that (i) former reports on right hemisphere shifts in language dominance with positive schizotypy might be explained by an associated higher substance use and (ii) cognitive disorganisation relates to unstable cognitive functioning that depend on individuals' life circumstances, contributing to published reports on inconsistent laterality-schizotypy relationships.

Cigarette smoking in male patients with chronic schizophrenia in a Chinese population: prevalence and relationship to clinical phenotypes

The high prevalence of smoking in schizophrenia of European background may be related to smoking's reducing clinical symptoms and medication side effects. Because smoking prevalence and its associations with clinical phenotypes are less well characterized in Chinese than European patients with schizophrenia, we assessed these smoking behaviors using clinician-administered questionnaires and the Fagerstrom Test for Nicotine Dependence (FTND) in 776 Chinese male schizophrenia and 560 control subjects. 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). We found that the schizophrenia patients had a higher lifetime incidence of smoking (79% vs 63%), were more likely to be heavy smokers (61% vs 31%), and had lower smoking cessation rates (4% vs 9%) (all p<0.0001) than controls. Among the schizophrenia patients smoking prevalence increased with age, with the largest difference from controls in the age cohort of 55-75 years: 75% vs 46% (p<0.0001). Among the schizophrenia smokers 73% started to smoke before the onset of their illness by an average of 7.6 years. The patients with schizophrenia who were current smokers scored significantly lower on the PANSS negative symptom subscore (p<0.005), and on the SAES symptom scale (p<0.04; Bonferroni corrected p>0.05) than the non-smoking patients. These results suggest that Chinese males with schizophrenia smoke more frequently than the general population. Further, smokers with schizophrenia may display fewer negative symptoms and possibly less parkinsonism than non-smokers with schizophrenia.

Personality disorders and the 3-year course of alcohol, drug, and nicotine use disorders

CONTEXT

Little is known about the role of a broad range of personality disorders in the course of substance use disorder (SUD) and whether these differ by substance. The existing literature focuses mostly on antisocial personality disorder and does not come to clear conclusions.

OBJECTIVE

To determine the association between the 10 DSM-IV personality disorders and the persistence of common SUDs in a 3-year prospective study of a national sample.

DESIGN

Data were drawn from participants in the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) who had alcohol dependence (n = 1172), cannabis use disorder (n = 454), or nicotine dependence (n = 4017) at baseline and who were reinterviewed 3 years later. Control variables included demographic characteristics, family history of substance disorders, baseline Axis I disorders and treatment status, and prior SUD duration. Main Outcome Measure  Persistent SUD, defined as meeting full criteria for the relevant SUD throughout the 3-year follow-up period.

RESULTS

Persistent SUD was found among 30.1% of participants with alcohol dependence, 30.8% with cannabis use disorder, and 56.6% with nicotine dependence at baseline. Axis I disorders did not have strong or consistent associations with persistent SUD. In contrast, antisocial personality disorder was significantly associated with persistent alcohol, cannabis, and nicotine use disorders (adjusted odds ratios, 2.46-3.51), as was borderline personality disorder (adjusted odds ratios, 2.04-2.78) and schizotypal personality disorder (adjusted odds ratios, 1.65-5.90). Narcissistic, schizoid, and obsessive-compulsive personality disorders were less consistently associated with SUD persistence.

CONCLUSIONS

The consistent findings on the association of antisocial, borderline, and schizotypal personality disorders with persistent SUD indicates the importance of these personality disorders in understanding the course of SUD. Future studies should examine dimensional representations of personality disorders and the role of specific components of these disorders, biological and environmental contributors to these relationships, and potential applications of these findings to treatment development.

Genetics of schizophrenia and smoking: an approach to studying their comorbidity based on epidemiological findings

The association between schizophrenia and tobacco smoking has been described in more than 1,000 articles, many with inadequate methodology. The studies on this association can focus on: (1) current smoking, ever smoking or smoking cessation; (2) non-psychiatric controls or controls with severe mental illness (e.g., bipolar disorder); and (3) higher smoking frequency or greater usage in smokers. The association with the most potential for genetic studies is that between ever daily smoking and schizophrenia; it may reflect a shared genetic vulnerability. To reduce the number of false-positive genes, we propose a three-stage approach derived from epidemiological knowledge. In the first stage, only genetic variations associated with ever daily smoking that are simultaneously significant within the non-psychiatric controls, the bipolar disorder controls and the schizophrenia cases will be selected. Only those genetic variations that are simultaneously significant in the three hypothesis tests will be tested in the second stage, where the prevalence of the genes must be significantly higher in schizophrenia than in bipolar disorder, and significantly higher in bipolar disorder than in controls. The genes simultaneously significant in the second stage will be included in a third stage where the gene variations must be significantly more frequent in schizophrenia patients who did not start smoking daily until their 20s (late start) versus those who had an early start. Any genetic approach to psychiatric disorders may fail if attention is not given to comorbidity and epidemiological studies that suggest which comorbidities are likely to be explained by genetics and which are not. Our approach, which examines the results of epidemiological studies on comorbidities and then looks for genes that simultaneously satisfy epidemiologically suggested sets of hypotheses, may also apply to the study of other major illnesses.

Relationship between smoking and family history of smoking in schizophrenia patients

BACKGROUND

The rate of smoking is known to be high in patients with schizophrenia. The purpose of this study was to quantitatively examine the relationship between smoking and family history of smoking in patients with schizophrenia.

METHODS

The sample consisted of 172 patients (mean age: 54 years, 55% male) hospitalized in a general psychiatric hospital. They were asked by a physician whether they smoked. Family histories of smoking and schizophrenia were assessed among first- and third-degree relatives.

RESULTS

Ninety-eight patients (57%) were identified as having smoked at some point. Multiple logistic regression analysis showed that smoking was significantly associated with family histories of smoking among both first- and third-degree relatives, controlling for the effects of age, sex, and family history of schizophrenia. The smoking rates were significantly higher in those with a family history of smoking, but not a family history of schizophrenia, than among those without a family history of either smoking or schizophrenia. However, this difference did not reach statistical significance among those with a family history of schizophrenia.

CONCLUSION

Smoking is greatly influenced by family history of smoking in patients with schizophrenia, especially among those without a family history of schizophrenia. The association between smoking and family history of smoking was inconclusive among those patients with schizophrenia who also had a family history of schizophrenia.

Prolactin levels and sexual adverse effects in patients with schizophrenia during antipsychotic treatment

OBJECTIVE

Patients with schizophrenia often experience sexual dysfunction (SD), to which disorder-related factors like negative symptoms and nondisorder-related factors can theoretically contribute. Thus, we investigated the correlation of SD and serum prolactin level in patients with schizophrenia during antipsychotic treatment.

METHODS

We included 39 patients with schizophrenia with a mean age of 34.6 years who were switched to second-generation antipsychotics into the study. Sexual adverse effects (via a specific scale) and serum prolactin levels were measured at baseline and week 4.

RESULTS

In males, mean prolactin levels increased over 4 weeks at a trend level of significance. Although a high incidence of SD was reported at baseline, there were no statistically significant changes over the course of 4 weeks. At baseline, a positive correlation between diminished sexual desire and prolactin levels could be found in men, which was not found in women; at week 4, both male and female patients demonstrated a positive correlation between orgastic dysfunction and prolactin levels. We found significant positive correlations between changes in prolactin levels over 4 weeks and changes in orgastic dysfunction for both sexes. Regression analyses showed prolactin levels at baseline to be a predictor of diminished sexual desire in men. Change in prolactin level was found to be a predictor of change for diminished sexual desire in women and for orgastic dysfunction in both sexes.

CONCLUSION

We conclude that the potential of antipsychotics to increase serum prolactin levels imposes a certain risk that patients will experience SD of varying severity.

The influence of tobacco consumption on the relationship between schizotypy and hemispheric asymmetry

Tobacco use is positively associated with severity of symptoms along the schizophrenia spectrum. Accordingly it could be argued that neuropsychological performance, formerly thought to be modulated by schizotypy, is actually modulated by drug use or an interaction of drug use and schizotypy. We tested whether habitual cigarette smokers as compared to non-smokers would show a neuropsychological profile similar to that observed along the schizophrenia spectrum and, if so, whether smoking status or nicotine dependence would be more significant modulators of behavior than schizotypy. Because hemispheric dominance has been found to be attenuated along the schizophrenia spectrum, 40 right-handed male students (20 non-smokers) performed lateralized left- (lexical decisions) and right- (facial decision task) hemisphere dominant tasks. All individuals completed self-report measures of schizotypy and nicotine dependence. Schizotypy predicted laterality in addition to smoking status: While positive schizotypy (Unusual Experiences) was unrelated to hemispheric performance, Cognitive Disorganization predicted reduced left hemisphere dominant language functions. These latter findings suggest that Cognitive Disorganization should be regarded separately as a potentially important mediator of thought disorganization and language processing. Additionally, increasing nicotine dependence among smokers predicted a right hemisphere shift of function in both tasks that supports the role of the right hemisphere in compulsive/impulsive behavior.

Cigarette smoking across the schizotypy spectrum

This study examined relationships between schizotypy symptom dimensions and smoking. Individuals with schizotypy (n=81) were twice as likely to smoke as individuals in a normative reference group (n=303). Among those with schizotypy, smokers reported more severe disorganization and less severe negative schizotypal symptoms. These findings offer insight into mechanisms underlying smoking in schizotypal individuals and suggest areas for further research.

Substance use in adolescence and psychosis: clarifying the relationship

Adolescence is a time of exploration of the self, and this exploration may involve the use of alcohol and drugs. Sadly, for some, adolescence also marks the first signs of a psychosis. The temporal proximity between the onset of substance use and of psychosis has been the cause of much debate. Here we review the association of alcohol, cannabis, stimulants, and other drugs with psychosis, and we conclude that the use of cannabis and the amphetamines significantly contributes to the risk of psychosis.

Smoking initiation and schizophrenia: a replication study in a Chinese Han population

Schizophrenia is associated with a greater probability of ever smoking daily and with higher rates of initiation of daily smoking after age 20 in Caucasian populations. The aims of the current study were to replicate that schizophrenia is associated with smoking and higher risk of initiating daily smoking before schizophrenia starts among a large sample of male Chinese patients. A survival analysis of onset age for daily smoking compared 776 DSM-IV male inpatients with schizophrenia to 560 male controls. The results showed that the cumulative hazard curves for age of smoking initiation in schizophrenia and controls were significantly different (p<0.001), even after controlling for education (p<0.001). After excluding the patients who started smoking within 5 years before schizophrenia started, the cumulative hazard curve for schizophrenia was significantly different from ever-smoked controls (p<0.001), even after adjusting for education (p<0.001). These findings suggest that schizophrenic patients have a higher risk of starting daily smoking suggesting that vulnerability to schizophrenia may be associated with a higher risk of becoming a daily smoker.

Cigarette smoking in patients with schizophrenia in China: prospective, multicentre study

OBJECTIVE

The aim of the present study was to explore the rate of cigarette smoking and its sociodemographic and clinical characteristics in Chinese schizophrenia patients.

METHODS

In a multicentre, randomized, controlled, longitudinal study, 374 clinically stable patients with schizophrenia were interviewed at entry using standardized assessment instruments, and followed up for 1-2 years.

RESULTS

The rate of cigarette smoking was 13.9% in the whole sample, and 26.2% in men and 3.5% in women. On univariate analysis, male sex, unemployment, alcohol consumption, older age, older age at onset, longer duration of illness, more frequent admissions, more severe hostility-excitement at entry and less deterioration in hostility-excitement over the study period were significantly associated with cigarette smoking. On multivariate analysis, male sex, unemployment, alcohol consumption, more frequent admissions, less severe positive and negative symptoms at entry, smaller decline in negative symptoms and more deterioration in disorganized thoughts over the study period were independently associated with cigarette smoking.

CONCLUSION

The rate of cigarette smoking in Chinese schizophrenia patients is considerably lower than most figures reported in the Western literature.

Differential effects on T-cell function following exposure to serum from schizophrenia smokers

Cigarette smoking is more prevalent in subjects with schizophrenia compared to those with other psychiatric disorders or the general population and could therefore affect molecular pathways that impact the pathophysiology of this disorder. As smoking is also known to suppress immune responses, we investigated the effects of 'smoking-conditioned' serum obtained from schizophrenia and control subjects on healthy T cell in vitro. We found that T-cell proliferation was significantly increased following exposure to serum from smoking schizophrenia patients whereas no effect was observed when using serum from smoking control subjects or non-smoking patients and controls. We eliminated the possibility that these effects were due to quantitative differences in cigarette consumption as serum levels of the stable nicotine metabolite cotinine were similar in schizophrenic and control smokers. Molecular characterization showed that serum from patient smokers increased expression of T-cell activation markers CD69(high), CD25(high), co-stimulatory molecules CD26+, CD27+ and CD28+, and decreased T-cell receptor complex components TCRalpha/beta and CD3. Moreover, analysis of supernatants collected after T-cell exposure to serum from smoking patients showed a time-dependent decline in interleukin (IL)-2 levels, suggesting that the proliferation effect is promoted by enhanced IL-2 processing. These results suggest that cigarette smoking has selective effects on serum components that, in turn, lead to altered immune function in schizophrenia patients relative to healthy subjects. Further studies aimed at characterizing these components could result in a better understanding of the onset and aetiology of schizophrenia and potentially lead to novel therapeutic strategies.

Relationship between prepulse inhibition of acoustic startle response and schizotypy in healthy Japanese subjects

Prepulse inhibition (PPI) of the acoustic startle reflex (ASR) is the most common psychophysiological index of sensorimotor gating. Several studies have investigated the relationship of PPI of ASR to schizotypy in Caucasians. However, little has been reported on this relationship in Asians. We investigated a possible relationship between PPI of ASR and schizotypy in 79 healthy Japanese subjects. Schizotypy was assessed by the Schizotypal personality Questionnaire (SPQ). PPI was evaluated at signal-to-noise ratios (SnRs: difference between background noise intensity and prepulse intensity) of +12, +16, and +20 dB. The total SPQ score, cognitive/perceptual score, and interpersonal score correlated negatively with PPI at SnR of +16 and +20 dB. We conclude that PPI is associated with the trait of schizotypy in healthy Asian subjects.

Associations between past alcohol, cannabis, and cocaine use and current schizotypy among first-degree relatives of patients with schizophrenia and non-psychiatric controls

Associations between past use of alcohol, cannabis, and cocaine and various domains of schizotypy were examined in first-degree relatives of patients with schizophrenia and non-psychiatric controls. Substance use was operationalized in three ways: (1) having ever used the substance, (2) age at first use, and (3) past frequency/amount of use during three time periods in late adolescence/early adulthood. Schizotypy was assessed using the Schizotypal Personality Questionnaire (SPQ). Participants who had ever used cannabis had significantly higher cognitive-perceptual, interpersonal, and total schizotypy scores compared to those who had not. Younger age of alcohol use onset was associated with more schizotypy in adulthood, and younger age of first cannabis use was related to more interpersonal schizotypy. More frequent/heavier use of alcohol in the 25-29 age-range, and cannabis in early adulthood, were associated with more schizotypy. The use of addictive substances, particularly cannabis, is related to schizotypy in complex ways.

Smoking, nicotine and neuropsychiatric disorders

Tobacco smoking is an extremely addictive and harmful form of nicotine (NIC) consumption, but unfortunately also the most prevalent. Although disproportionately high frequencies of smoking and its health consequences among psychiatric patients are widely known, the neurobiological background of this epidemiological association is still obscure. The diverse neuroactive effects of NIC and some other major tobacco smoke constituents in the central nervous system may underlie this association. This present paper summarizes the pharmacology of NIC and its receptors (nAChR) based on a systematic review of the literature. The role of the brain's reward system(s) in NIC addiction and the results of functional and structural neuroimaging studies on smoking-related states and behaviors (i.e. dependence, craving, withdrawal) are also discussed. In addition, the epidemiological, neurobiological, and genetic aspects of smoking in several specific neuropsychiatric disorders are reviewed and the clinical relevance of smoking in these disease states addressed.

Schizotypy and nicotine, alcohol, and cannabis use in a non-psychiatric sample

Schizotypy is a multidimensional personality construct that is characterized by perceptual abnormalities, social withdrawal, mild suspiciousness, and odd thinking patterns. This study examined the relationship between four dimensions of self-reported schizotypy and substance use involving nicotine, alcohol, and cannabis, in undergraduate students. Results showed that higher levels of disorganized schizotypy, or odd thinking and behavior, were associated with greater indices of use of all three substances. Furthermore, higher cognitive-perceptual schizotypy was selectively associated with cannabis use. Results confirm findings of recent research that has discovered associations among schizotypy and substance use, highlighting links between behavioral traits and use of nicotine, alcohol, and cannabis. This study is one of the first to examine a wide range of schizotypy domains, and to show selective effects of the disorganized domain of schizotypy.

The association between schizophrenia and smoking: unexplained by either the illness or the prodromal period

Age at onset of daily smoking (AODS) was compared in schizophrenia (N=258), mood disorders (N=166) and controls (N=381) to replicate a different AODS in schizophrenia patients, and to confirm that this is not necessarily explained by the prodromal period. The cumulative hazard curves for schizophrenia, mood disorders and controls were significantly different (p<0.001), even after controlling for gender and education (p<0.001). After excluding the patients who started smoking within 5 years of starting psychiatric medication, the cumulative hazard curve for schizophrenia patients was significantly different from that for ever-smoker controls (p=0.002), even after adjusting for gender and education (p=0.03).