Latent factor structure of a behavioral economic cigarette demand curve in adolescent smokers

Abstract

Behavioral economic demand curves, or quantitative representations of drug consumption across a range of prices, have been used to assess motivation for a variety of drugs. Such curves generate multiple measures of drug demand that are associated with cigarette consumption and nicotine dependence. However, little is known about the relationships among these facets of demand. The aim of the study was to quantify these relationships in adolescent smokers by using exploratory factor analysis to examine the underlying structure of the facets of nicotine incentive value generated from a demand curve measure. Participants were 138 adolescent smokers who completed a hypothetical cigarette purchase task, which assessed estimated cigarette consumption at escalating levels of price/cigarette. Demand curves and five facets of demand were generated from the measure: Elasticity (i.e., 1/α or proportionate price sensitivity); Intensity (i.e., consumption at zero price); O(max) (i.e., maximum financial expenditure on cigarettes); P(max) (i.e., price at which expenditure is maximized); and Breakpoint (i.e., the price that suppresses consumption to zero). Principal components analysis was used to examine the latent structure among the variables. The results revealed a two-factor solution, which were interpreted as "Persistence," reflecting insensitivity to escalating price, and "Amplitude," reflecting the absolute levels of consumption and price. These findings suggest a two factor structure of nicotine incentive value as measured via a demand curve. If supported, these findings have implications for understanding the relationships among individual demand indices in future behavioral economic studies and may further contribute to understanding of the nature of cigarette reinforcement.

Figure 1

Prototypic cigarette demand and expenditure curves. Data are provided in conventional log–log units for proportionality. Zero prices are not presented to permit logarithmic units. In Panel A, Intensity reflects consumption at zero or minimum price; P_max reflects the price at which demand becomes elastic (i.e., disproportionately decreasing relative to increases in price); and Breakpoint is reflects the price at which consumption is completely suppressed; Elasticity is a property of the aggregate curve and is thus not depicted. In Panel B, O_max refers to maximum expenditure on cigarettes across prices and corresponds with the P_max price.