Background Simultaneous Alcohol and Cannabis (SAC) use is associated with greater negative consequences than individual use. Motives to use are robust predictors of alcohol and cannabis consumption, both separately and simultaneously. While instruments such as the SAC Motives Scale and its short form have recently been developed, no Spanish adaptation is currently available.

Aims To provide a Spanish adaptation of both versions of the simultaneous alcohol and cannabis motives measure and to examine its psychometric properties in a sample of young adults who simultaneously consume both substances.

Method A targeted sampling procedure was used to recruit 612 young cannabis users, of whom 479 reported SAC use (18-25 years old [M = 21.01, SD = 2.14]; 36% female). Following adaptation and translation, participants completed the scale, along with measures of alcohol, cannabis, and simultaneous use, cannabis motives, and alcohol- and cannabis- related negative consequences.

Results Confirmatory factor analyses showed a four-factor structure (conformity, positive effects, calm/coping, and social). Moreover, the results indicated acceptable internal consistency (.70 - .88), providing evidence of convergent, discriminant, and predictive validity for most dimensions.

Conclusions The results suggest that both versions of the scale are valuable tools for assessing motives for SAC consumption among young adults. These scales could aid in investigating motives for SAC use and informing interventions to mitigate associated harms.

Public Significance Statement This study provides the first Spanish adapted-version measure to assess motives for Simultaneous Alcohol and Cannabis (SAC) consumption. Our findings support the use of this measure for assessing these motives and guiding interventions aimed at preventing or reducing SAC use and its negative consequences among Spanish-speaking young adults who use alcohol and cannabis simultaneously.

The authors have declared no competing interest.

This work was funded by the Agencia Estatal de Investigacion (Ministerio de Ciencia, Innovacion y Universidades, Spain; MICIU/AEI//10.13039/501100011033/) under grant number PID2020-118229RB-I00 (Principal Investigator: Fermin Fernandez Calderon).

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The Regional Bioethics Research Committee of Andalusia (Consejeria de Sanidad, Junta de Andalucia, Spain) gave ethical approval for this work.

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