Potent Dopamine D2 Antagonists Block the Reward-Enhancing Effects of Nicotine in Smokers With Schizophrenia

Alexis E. Whitton; Alan I. Green; Diego A. Pizzagalli; Robert M. Roth; Jill M. Williams; Mary F. Brunette


Schizophr Bull. 2019;45(6):1300-1308. 

In This Article

Data Reduction and Statistical Analyses

PRT Quality Assurance and Data Reduction

In line with prior PRT studies,[32,49] data were subjected to quality control analyses that involved excluding trials with reaction times of less than 150 ms or greater than 2500 ms, and data from participants who had accuracy scores below 50% (indicative of below-chance level performance), or from participants who had more than 25% reaction time outlier trials. Next, signal detection analysis[50] was used to calculate response bias (the tendency to bias responding to the rich stimulus) and discriminability (the ability to accurately distinguish between the 2 mouth sizes), according to the following formulas:

In accordance with recommendations,[51] 0.5 was added to every cell of the detection matrix to allow for log-transformation of cells containing a zero.

Statistical Analysis

A repeated measures analysis of variance (ANOVA) with medication (D2 antagonism+, D2 antagonism–) as the between-subject factor, and smoking (pre-smoke, post-smoke) and block (block 1, block 2) as within-subject factors, was used to examine the degree to which the presence of potent D2 receptor antagonists moderated the effects of smoking on response bias. Significant interaction effects were followed up with tests of simple effects. Furthermore, bivariate Pearson correlations were used to examine the degree to which smoking-induced changes in response bias correlated with nicotine dependence on the FTND and smoking urges on the QSU.