Latent structure of facets of alcohol reinforcement from a behavioral economic demand curve.

RATIONALE: Behavioral economic demand curves are quantitative representations of the relationship between consumption of a drug and its cost. Demand curves provide a multidimensional assessment of reinforcement, but the relationships among the various indices of reinforcement have been largely unstudied.
OBJECTIVES: The objective of the study is to use exploratory factor analysis to examine the underlying factor structure of the facets of alcohol reinforcement generated from an alcohol demand curve.
MATERIALS AND METHODS: Participants were 267 weekly drinkers [76% female; age M = 20.11 (SD = .1.51); drinks/week M = 14.33 (SD = 11.82)] who underwent a single group assessment session. Alcohol demand curves were generated via an alcohol purchase task, which assessed consumption at 14 levels of prices from $0 to $9. Five facets of demand were generated from the measure [intensity, elasticity, P (max) (maximum inelastic price), O (max) (maximum alcohol expenditure), and breakpoint], using both observed and derived calculations. Principal components analysis was used to examine the latent structure among the variables.
RESULTS: The results revealed a clear two-factor solution, which were interpreted as "Persistence," reflecting sensitivity to escalating price, and "Amplitude," reflecting the amount consumed and spent. The two factors were generally quantitatively distinct, although O (max) loaded on both.
CONCLUSIONS: These findings suggest that alcohol reinforcement as measured via a demand curve is binary in nature, with separate dimensions of price-sensitivity and volumetric consumption. If supported, these findings may contribute theoretically and experimentally to a reinforcement-based approach to alcohol use and misuse.