Association of behavioral economic demand for kratom with DSM-5 use disorder: quantity and likelihood-based demand...

Kratom products have increased in popularity in the United States due to their availability and their purported analgesic and stimulatory properties. We sought to examine if behavioral economic demand procedures widely used in addiction science would identify indicators of problematic kratom use and to evaluate the relative performance of differing demand approaches.

Respondents with a lifetime history of kratom use (N = 117) completed two versions of a hypothetical kratom purchase task. The first version ("Quantity") followed typical purchase task methods; respondents were asked how much kratom they would purchase across various prices. The second version ("Likelihood") asked how likely respondents would be to purchase a single dose of kratom across the same price range. Logistic regression was used to determine the association of demand indices with the likelihood of meeting KUD criteria.

For the Quantity version, higher demand intensity (OR = 2.16, p = 0.01) and lower demand elasticity (OR = 0.45, p = 0.01) were significantly associated with past year but not lifetime KUD (p's > 0.10). For the Likelihood version, demand intensity, demand elasticity, and Pmax were not associated with KUD (p's > 0.10); higher breakpoint was associated with past year, but not lifetime KUD (OR = 1.44, p = 0.04).

This study is the first to demonstrate that purchase tasks can quantify the reinforcing efficacy of kratom and emphasizes the temporal specificity of the association between purchase tasks and problem behaviors. These findings also suggest that demand indices from Quantity- and Likelihood-based tasks differentially relate to KUD, emphasizing the importance of task and outcome selection.