Normalization of auditory physiology by cigarette smoking in schizophrenic patients

Department of Psychiatry, Denver VA Medical Center, CO.
American Journal of Psychiatry (Impact Factor: 12.3). 01/1994; 150(12):1856-61. DOI: 10.1176/ajp.150.12.1856
Source: PubMed


Because many schizophrenic patients are heavy smokers, it has been suggested that nicotine normalizes some neuronal deficit involved in their illness. Schizophrenic subjects have various difficulties with maintenance of attention and selective processing of sensory information. One defect in sensory gating in schizophrenia has been characterized by recording auditory evoked potentials. Most normal subjects have a decrease in the evoked response to the second of two closely paired stimuli, whereas most schizophrenic subjects do not. The aim of this study was to determine whether smoking normalizes this deficit in auditory sensory gating in schizophrenia.
Changes in auditory sensory gating in response to smoking cigarettes were studied in 10 smokers without psychiatric illness and 10 schizophrenic smokers. Both groups were asked to abstain from smoking from 11:00 p.m. until 8:00 a.m. the next morning, when their auditory evoked responses to pairs of clicks were recorded. The ability to gate sensory information is reflected in a decrease in the P50 wave amplitude in response to the second of the two stimuli. After baseline recordings, the subjects smoked as much as they wished, and then two postsmoking recordings were performed.
The schizophrenic patients had a marked but brief improvement in P50 auditory gating immediately after smoking, whereas P50 gating for the normal smokers was slightly impaired.
This study suggests that cigarette smoking can transiently normalize the impairment of auditory sensory gating in schizophrenic patients.

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    • "Patients with schizophrenia usually show defi cits in both paradigms: PPI (e.g., Aggernaes et al. 2010; Braff et al. 1978), P50 suppression: (e.g., Adler et al. 1982; Boutros et al. 1991; Oranje et al. 2013). There is some evidence indicating that gating defi cits can be ameliorated by among others, nicotine (Adler et al. 1993; Raux et al. 2002; Houy et al, 2004) and α 2a-noradrenergic agonists (Oranje and Glenth ø j 2013, 2014). P50 suppression and PPI defi cits are considered as interesting endophenotypes in schizophrenia. "
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    ABSTRACT: The neurophysiological components that have been proposed as biomarkers or as endophenotypes for schizophrenia can be measured through electroencephalography (EEG) and magnetoencephalography (MEG), transcranial magnetic stimulation (TMS), polysomnography (PSG), registration of event-related potentials (ERPs), assessment of smooth pursuit eye movements (SPEM) and antisaccade paradigms. Most of them demonstrate deficits in schizophrenia, show at least moderate stability over time and do not depend on clinical status, which means that they fulfil the criteria as valid endophenotypes for genetic studies. Deficits in cortical inhibition and plasticity measured using non-invasive brain stimulation techniques seem promising markers of outcome and prognosis. However the utility of these markers as biomarkers for predicting conversion to psychosis, response to treatments, or for tracking disease progression needs to be further studied.
    The World Journal of Biological Psychiatry 08/2015; 16(5):280-90. DOI:10.3109/15622975.2015.1050061 · 4.18 Impact Factor
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    • "Experimental participants attended two morning appointments (approximately one week apart), one after abstaining from nicotine from at least 11 pm (e.g. Adler et al.1993; 'abstinent'), the other in the context of usual smoking behaviour ('smoking'). The order of cognitive assessment was randomly allocated from one of six testing orders, generated using a Latin square design. "
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    ABSTRACT: Smoking prevalence in schizophrenia is significantly elevated relative to other clinical and to non-clinical groups. The cognitive self-medication hypothesis attributes this to the beneficial effects of nicotine on illness-related cognitive deficits. Significant effects of nicotine have been observed on visual spatial working memory (VSWM), sustained attention (Continuous Performance Test — Identical Pairs; CPT-IP) and prepulse inhibition (PPI). It remains unclear whether these neurophysiological and neurocognitive effects of nicotine influence self-reported smoking motivation.
    Schizophrenia Research: Cognition 01/2015; 32(1). DOI:10.1016/j.scog.2014.12.001
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    • "Basic research in rodents has consistently demonstrated that nicotinic agonists improve auditory gating in mouse P20 potential , which is an analog of human P50 (Adler et al., 1998; Radek et al., 2006; Stevens and Wear, 1997). Moreover, high doses of nicotine significantly improve P50 suppression abnormalities in both schizophrenia patients (Adler et al., 1993) and their family members (Adler et al., 1992), further suggesting that brain nicotinic acetylcholine systems regulate at least some of these gating deficits (Olincy et al., 2006). In human studies, P50 suppression deficits have been linked to the locus of the alpha-7 nicotinic cholinergic receptor (Freedman et al., 1997). "
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    ABSTRACT: Background The effects of smoking on cognitive performance have long been studied, with mixed results. P50 sensory gating has been used as endophenotype for studying nicotinic systems genetics, and P50 gating deficits have been reported to be a sensitive biomarker for cognitive impairment in schizophrenia. This study examined the inter-relationship between P50 suppression, cognitive function, and smoking in a healthy Han Chinese population, which has not been reported before. Methods We recruited 82 healthy male subjects, including 48 smokers and 34 non-smokers who were matched for age and education. The authors measured P50 sensory gating and administered the Chinese-language version of the MATRICS Consensus Cognitive battery (MCCB) and Stroop tests. Results The results showed that the smokers scored lower than nonsmokers on the MCCB Brief Visuospatial Memory Test (BVMT) index and the STROOP test. Furthermore, the MCCB total score was negatively associated with number of cigarettes smoked per day in the smoker group. However, P50 sensory gating was not associated with either smoking status or any cognitive performance. Conclusions Our results show that smoking is associated with cognitive impairment, but not with P50 sensory gating.
    Drug and Alcohol Dependence 10/2014; 143(1). DOI:10.1016/j.drugalcdep.2014.06.045 · 3.42 Impact Factor
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