Higher nicotine levels in schizophrenia compared with controls after smoking a single cigarette

Abstract

Introduction: The increase in blood nicotine after smoking a single cigarette is nicotine boost. We hypothesized that smokers with schizophrenia (SCZ) have a greater nicotine boost than controls without this disorder.

Methods: Twenty-one subjects (11 SCZ and 10 controls, CON) had repeated venous blood sampling before, during, and after smoking a single cigarette after 12-hr abstinence to measure nicotine concentrations. Blood samples were drawn at baseline (before smoking) and 1, 2, 4, 6, 8, 10, 20, 30, 60, 90, and 120 min after the first puff. Groups were similar in baseline characteristics, including gender and level of dependence, and all smoked 20-30 cigarettes/day. Area under the serum nicotine concentration-time curve (AUC(20)) was calculated for time up to 20 min after the start of smoking.

Results: The mean difference in AUC(20) was significantly greater for SCZ versus CON (135.4 ng-min/ml; 95% CI = 0.45-283.80). The shape of the nicotine concentration-time curve for SCZ was significantly different compared with controls (p < .01). Nicotine boost in the first 4 min of smoking was higher in SCZ versus CON (25.2 vs. 11.1 ng/ml, p < .01) with no difference in the total time spent smoking.

Discussion: This technique improves on methods, which draw only two blood specimens to assess nicotine intake. Understanding how nicotine boost differs in SCZ from CON may explain high levels of addiction and low success in cessation in smokers with SCZ.

Figure 1.

Predicted values of SCZ and CON were obtained from the polynomial mixed model analysis with fixed effects (p < .001 for time to the sixth power for both SCZ and CON): y = 11.67 + 0.97 × (time − 29.25) + 0.07 × (time − 29.25)² − 0.003 × (time − 29.25)³ − 7.01 × 10⁻⁰⁵ × (time − 29.25)⁴ + 2.87 × 10⁻⁶ × (time − 29.25)⁵ − 2.01 × 10⁻⁸ × (time − 29.25)⁶ for SCZ and y = 8.01 + 0.30 × (time − 29.25) + 0.03 × (time − 29.25)² − 0.001 × (time − 29.25)³ − 3.01 × 10⁻⁵ × (time − 29.25)⁴ + 1.34 × 10⁻⁶ × (time − 29.25)⁵ − 9.17 × 10⁻⁸ × (time − 29.25)⁶ for CON. To minimize extrapolation error due to no measurements between the following intervals, the polynomial curves over these intervals were connected by straight line segments between 10 and 20, 20 and 30, 30 and 60, 60 and 90, and 90 and 120 min.