Smoking and schizophrenia

Steeper discounting of delayed rewards in schizophrenia but not first-degree relatives

Excessive discounting of future rewards has been related to a variety of risky behaviors and adverse clinical conditions. Prior work examining delay discounting in schizophrenia suggests an elevated discount rate. However, it remains uncertain whether this reflects the disease process itself or an underlying genetic vulnerability, whether it is selective for delay discounting or reflects pervasive changes in decision-making, and whether it is driven by specific clinical dimensions such as cognitive impairment. Here we investigated delay discounting, as well as loss aversion and risk aversion, in three groups: schizophrenia (SZ), unaffected first-degree family members (FM), and controls without a family history of psychosis (NC). SZ had elevated discounting, without changes in loss aversion or risk aversion. Contrary to expectations, the FM group did not show an intermediate phenotype in discounting. Higher discount rates correlated with lower cognitive performance on verbal reasoning, but this did not explain elevated discount rates in SZ. Group differences were driven primarily by the non-smoking majority of the sample. This study provides further evidence for elevated discounting in schizophrenia, and demonstrates that steeper discounting is not necessarily associated with familial risk, cannot be wholly accounted for by cognitive deficits, and is not attributable to smoking-related impulsivity.

Nicotine receptors mediating sensorimotor gating and its enhancement by systemic nicotine

Prepulse inhibition (PPI) of startle occurs when intensity stimuli precede stronger startle-inducing stimuli by 10–1000 ms. PPI deficits are found in individuals with schizophrenia and other psychiatric disorders, and they correlate with other cognitive impairments. Animal research and clinical studies have demonstrated that both PPI and cognitive function can be enhanced by nicotine. PPI has been shown to be mediated, at least in part, by mesopontine cholinergic neurons that project to pontine startle neurons and activate muscarinic and potentially nicotine receptors (nAChRs). The subtypes and anatomical location of nAChRs involved in mediating and modulating PPI remain unresolved. We tested the hypothesis that nAChRs that are expressed by pontine startle neurons contribute to PPI. We also explored whether or not these pontine receptors are responsible for the nicotine enhancement of PPI. While systemic administration of nAChR antagonists had limited effects on PPI, PnC microinfusions of the non-α7nAChR preferring antagonist TMPH, but not of the α7nAChR antagonist MLA, into the PnC significantly reduced PPI. Electrophysiological recordings from startle-mediating PnC neurons confirmed that nicotine affects excitability of PnC neurons, which could be antagonized by TMPH, but not by MLA, indicating the expression of non-α7nAChR. In contrast, systemic nicotine enhancement of PPI was only reversed by systemic MLA and not by TMPH or local microinfusions of MLA into the PnC. In summary, our data indicate that non-α7nAChRs in the PnC contribute to PPI at stimulus intervals of 100 ms or less, whereas activation of α7nAChRs in other brain areas is responsible for the systemic nicotine enhancement of PPI. This is important knowledge for the correct interpretation of behavioral, preclinical, and clinical data as well as for developing drugs for the amelioration of PPI deficits and the enhancement of cognitive function.

Factors affecting smoking cessation efforts of people with severe mental illness: a qualitative study

OBJECTIVE

People with severe mental illness are much more likely to smoke than are members of the general population. Smoking cessation interventions that combine counseling and medication have been shown to be moderately effective, but quit rates remain low and little is known about the experiences of people with severe mental illness in smoking cessation interventions. To address this gap in knowledge, we conducted a qualitative study to investigate factors that help or hinder the smoking cessation efforts of people with severe mental illness.

METHODS

We recruited 16 people with severe mental illness who had participated in a clinical trial of two different smoking cessation interventions, one involving nicotine replacement therapy only and the other nicotine replacement therapy combined with motivational interviewing and a peer support group. We conducted open-ended, semi-structured interviews with participants, who ranged in age from 20 to 56 years old, were equally distributed by gender (eight men and eight women), and were predominantly Caucasian (n = 13, 81%). Primary mental illness diagnoses included schizophrenia/schizoaffective disorder (n = 6, 38%), depression (n = 5, 31%), bipolar disorder (n = 4, 25%), and anxiety disorder (n = 1, 6%). At entry into the clinical trial, participants smoked an average of 22.6 cigarettes per day (SD = 13.0).

RESULTS

RESULTS indicated that people with mental illness have a diverse range of experiences in the same smoking cessation intervention. Smoking cessation experiences were influenced by factors related to the intervention itself (such as presence of smoking cessation aids, group supports, and emphasis on individual choice and needs), as well as individual factors (such as mental health, physical health, and substance use), and social-environmental factors (such as difficult life events and social relationships).

CONCLUSIONS

An improved understanding of the smoking cessation experiences of people with severe mental illness can inform the delivery of future smoking cessation interventions for this population. The results of this study suggest the importance of smoking cessation interventions that offer a variety of treatment options, incorporating choice and flexibility, so as to be responsive to the evolving needs and preferences of individual clients.

[Prohibición de fumar y sus implicaciones potenciales en cuidados de salud mental. Revisión de la evidencia]

Different publications have described a close relation between tobacco consumption and major psychiatric disorders. A great number of countries have enacted smoking bans in public or working places since the early 2000s; nonetheless, concerns remain over the exemption in some psychiatric settings regarding smoking bans. Admission of smokers to smoke-free units may lead to behavior deterioration, but some recent evidence refutes this argument.

METHODS

Literature review.

RESULTS

One of the earliest smoking bans was a 1.575 Mexican ecclesiastical council ban aimed at smoking prevention in churches. Several recent studies have documented health and economic benefits related to smoking bans. Over 83 countries now have introduced different sorts of regulations. There was no increase in aggression, seclusion or discharge against medical advice, neither increased use of PRN (as needed) medication following the ban. As part of the ban imposition, Nicotine Replacement Therapy- NRT was used by patients. Consistency, coordination and full staff support for the ban were seen as key success factors. Many patients continued smoking after discharge.

CONCLUSIONS

Evidence shows that smoking has no place in psychiatric hospitals or facilities. The introduction of smoking bans in psychiatric settings is possible, but these bans must be conceived only as part of a much larger strategy, necessary to diminish smoking high rates among mental health populations.

Prepulse inhibition of the startle reflex: a window on the brain in schizophrenia

Prepulse inhibition (PPI) of the startle response is an important measure of information processing deficits and inhibitory failure in schizophrenia patients. PPI is especially useful because it occurs in the same lawful manner in all mammals, from humans to rodents, making it an ideal candidate for cross-species translational research. PPI deficits occur across the "schizophrenia spectrum" from schizophrenia patients to their clinically unaffected relatives. Parallel animal model and human brain imaging studies have demonstrated that PPI is modulated by cortico-striato-pallido-thalamic (and pontine) circuitry. This circuitry is also implicated in schizophrenia neuropathology and neurophysiology. The finding of PPI deficits in schizophrenia patients has been replicated by many groups, and these deficits correlate with measures of thought disorder and appear to be "normalized" by second generation antipsychotic (SGA) medications. Consistent pharmacological effects on PPI have been demonstrated; among these, dopamine agonists induce PPI deficits and (in animal models) these are reversed by first and SGA medications. PPI is also significantly heritable in humans and animals and can be used as a powerful endophenotype in studies of families of schizophrenia patients. Genomic regions, including the NRGL-ERBB4 complex with its glutamatergic influences, are strongly implicated in PPI deficits in schizophrenia. PPI continues to hold promise as an exciting translational cross-species measure that can be used to understand the pathophysiology and treatment of the schizophrenias via pharmacological, anatomic, and genetic studies.

Smokers and nonsmokers equally affected by olanzapine-induced weight gain: metabolic implications

OBJECTIVE

To examine the impact of smoking status on antipsychotic-associated weight gain.

METHOD

In two double-blind studies, 552 adult and elderly patients with schizophrenia or schizoaffective disorder were randomly assigned to risperidone or olanzapine treatment for 8 weeks. Smoking status at baseline was recorded together with other background characteristics.

RESULTS

In both adult and elderly patients, olanzapine-treated smokers and nonsmokers gained weight at a similar rate, whereas risperidone-treated smokers gained less weight than did nonsmokers. Olanzapine was associated with significantly greater weight gain than was risperidone across all measures in both adult and elderly patients.

CONCLUSION

These findings support a quantitatively or qualitatively different effect of risperidone and olanzapine on the metabolic changes underlying antipsychotic-associated weight gain. Mechanisms responsible for olanzapine's effect on weight appear to counteract smokers' physiologic bias toward weight loss, an effect not seen among risperidone-treated patients.

The association between schizophrenia and cigarette smoking: a review of the literature and implications for mental health nursing practice

Despite a fall in smoking activity among the general population, individuals with schizophrenia continue to smoke at alarming rates and suffer poor health as a consequence. It would appear that limited and conflicting knowledge, outdated perceptions, and ineffective interventions have hindered efforts to promote healthy behaviours among this group. This paper reviews the literature on the association between nicotine dependence and schizophrenia and explores explanations for the phenomenon. Complex psychopathological, biochemical, and neuropharmacological interactions between smoking and schizophrenia are revealed. The interface of schizophrenia and smoking behaviour, particularly among those hospitalized in mental health facilities, and rationales for the management of this manifestation are examined. In addition, inferences regarding the role of mental health nurses in the care of this population are reached, and implications for nursing practice are discussed.

Smoking in schizophrenia -- all is not biological

High rate of tobacco smoking reported in schizophrenia has been related to the effect of nicotine on the neurobiology of schizophrenia. Nicotine is said to alleviate psychotic symptoms in some patients. The relationship between smoking and psychiatric status may not be simply a biological one as several sociocultural and economic factors could influence smoking behaviour. In this study in India on 286 urban male outpatients with schizophrenia, only 38% were found to be current smokers. This was significantly more than in other psychiatric patients studied (major affective disorders and non-psychotic disorders) but not medically ill controls and not higher than the rates for the general male population in India. Smokeless use of tobacco was infrequent in the study population. More than half of the patients did not experience any positive effects due to smoking. Lack of economic independence and restrictions imposed by the family appeared to be crucial factors that controlled the prevalence of smoking among schizophrenia patients. As smoking is a leading cause of preventable morbidity and mortality, there is a serious need to review the neurobiological issue of smoking in schizophrenia considering the influence culture and social practices could have upon the behaviour.

Different outcomes after acute and chronic treatment with nicotine in pre-pulse inhibition in Lister hooded rats

Excessive tobacco consumption by schizophrenic patients may be a form of self-medication, and nicotine in tobacco may alleviate deficits in information processing. We tested this hypothesis by determining whether nicotine (acute/chronic) would improve information processing in the rat using pre-pulse inhibition as a model. In study 1, rats were injected with nicotine 10 min prior to placement in startle chambers (0.001-0.1 or 0.03-0.3 mg/kg, s.c.). In study 2, rats were injected with either saline or nicotine (0.4 mg/kg, s.c.) for 21 consecutive days and assessed for locomotor activity, pre-pulse inhibition and changes in [3H]nicotine binding in whole brain. Acutely, nicotine had no effect on pre-pulse inhibition. By contrast, after chronic nicotine treatment, rats demonstrated a robust deficit in pre-pulse inhibition and significant increases in locomotor activity and [3H]nicotine binding. The deficit in pre-pulse inhibition after chronic treatment with nicotine may be the result of non-specific behavioural activation due to increased mesolimbic dopamine release or, possibly, nicotine may rapidly desensitize nicotinic receptors important for normal information processing.

Addiction and schizophrenia

Epidemiologic studies in the general population and those based on the clinical assessment of schizophrenic populations have revealed a high degree of overlap between schizophrenia and addictive disorders. The abuse of psychoactive substances (including alcohol) throughout life is so frequent (50%) that the possibility of a specific link inevitably arises. Various hypotheses have been suggested to explain the high co-morbidity between schizophrenia and addiction: 1) The social-environmental hypothesis has been developed but studies have provided poor evidence to validate it. 2) The possible shared biological vulnerability between schizophrenia and addictions led researchers to explore common genetic determinants and study the involvement of the dopaminergic and opioid systems in the aetiology of both schizophrenia and the abuse of and dependence on psychoactive drugs. 3) Finally, the theory of self-medication suggests that schizophrenics may be attempting to counter the deficit linked to their disorders by using the substances they take or their dependency-type behaviour to cope with their emotional problems. The clinical profile of schizophrenic addicts does seem to display some distinctive features, such as the high level of depressive co-morbidity, very high nicotine and alcohol dependence, with a very poor prognosis. These patients are difficult to manage; the possibility of pharmacologic interactions between the substances they are taking and neuroleptic medication calls for prudence, and their compliance is also poor. Addictive disorders in schizophrenics are currently a topic of active research intended to lead to identifying specific treatments. The early identification of addictive disorders in schizophrenics should make it possible to limit their development and improve the prognosis.