Higher rates and severity of tobacco dependence in people with schizophrenia, as compared with the general population, contribute to the lower life expectancy seen in this population. Dependent tobacco smoking is controlled by how different aspects of cigarette smoking are perceived. There is evidence suggesting that people with schizophrenia differ in how they perceive cigarette smoking, which, if confirmed, would have implications for tailoring treatment interventions for smoking cessation in schizophrenia.
The aim of the present study is to determine whether tobacco smoking in people with schizophrenia is governed by different aspects and effects of cigarette consumption. Smokers participating in this study either have no psychiatric diagnosis, or a diagnosis of schizophrenia or schizoaffective disorder. Over four study visits, participants will sample and compare different research cigarettes, complete questionnaires and concentration tasks, and smoke one type of research cigarette for eight hours while wearing a nicotine patch. By shaping our understanding of tobacco dependence in schizophrenia, the present project may redirect treatment development toward strategies tailored to the specific vulnerabilities of this population, which is among the most severely affected by its detrimental impact on health and life.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Enrollment
31
Participants sample two research cigarettes, which differ in typical tobacco smoke constituents such as tar, nicotine, carbon monoxide, etc. In the Cigarette Discrimination Session, participants sample both types of cigarettes repeatedly, guess their identity (A or B) with regard to reference cigarettes, and rate their subjective effects. In the Ad Libitum Smoking Session, participants can smoke one of these cigarette types as much or as little as they like for eight hours.
Maryland Psychiatric Research Center
Catonsville, Maryland, United States
End-of-session Carbon Monoxide
The concentration (ppm) of carbon monoxide (CO) in breath is measured by exhalation into a CO breathalyzer at the end of the 8-hour Ad Libitum Smoking Session. Only very-low-nicotine-content (virtually nicotine-free) cigarettes were consumed in this session.
Time frame: One day (in the Ad Libitum Smoking Session), over an 8-hour time frame.
Cigarette Discrimination Accuracy
Participants sample 4 cigarettes of type A and 4 cigarettes of type B in a double-blind manner and indicate for each cigarette if they think it is of type A or B. Two reference trials with cigarette type unblinded will be performed before the first and fifth sample cigarette. For each sampled cigarette, the score is either 1 (correct) or 0 (incorrect). Discrimination accuracy is calculated by averaging the eight scores for each participant.
Time frame: One day (in the Cigarette Discrimination Session), over a 6-hour time frame.
Change in the Number of Research Cigarettes Smoked
In the Ad Libitum Smoking Session, participants can smoke as many research cigarettes (all very-low-nicotine-content) as they wish. The propensity to maintain smoking despite the absence of nicotine was quantified by subtracting the number of cigarettes smoked in the last two hours from that in the first two hours of the session. Smaller difference values indicate that smoking was upheld by very-low-nicotine-content cigarettes.
Time frame: One day (in the Ad Libitum Smoking Session), over an 8-hour time frame.
Difference in Subjective State Composite Score
The measure is derived by transforming scores on the Minnesota Nicotine Withdrawal Scale (where higher values signify more withdrawal), the Affect-based Withdrawal Scale (higher values signify a worse emotional state), Questionnaire for Smoking Urges (higher values indicate more craving), and modified Cigarette Evaluation Questionnaire (mCEQ, higher values indicate greater subjective effects of smoking on mood, hunger, physiology) into standard z-scores, thus giving each scale a mean of 0 and standard deviation of 1. Withdrawal and craving scores were re-poled (inversing the sign), and scales were averaged for each subject. The resulting composite quantified the subjective state response to cigarette smoking, larger values indicating less withdrawal, less craving, and larger effects on the mCEQ. The difference therein between the research cigarettes containing nicotine and those containing almost no nicotine quantified the subjective state response to nicotine.
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Time frame: One day (in the Cigarette Discrimination Session), over a 6-hour time frame.