The prospective relationship between craving and the likelihood of "unknown" substance use motive endorsement

Previous research and theory on substance use motives suggest that there are moments during which individuals use substances without clarity about why. Preliminary work investigating this motivational state has demonstrated a non-linear predictive relationship between positive and negative affect. Given research on "unknown" motives is in its nascent stage, we sought to further expand the contextual predictive factors that may also give rise to unknown motive endorsement. Craving is considered a central process in the onset and maintenance of SUDs but may fall outside a person's awareness. As such, we investigated if craving predicted "unknown" motive endorsement above and beyond the effects of positive and negative affect. Forty-nine undergraduate students (observations = 286; 32.7% AUD, 36.7% CUD, 30.6% both) completed a 2-week EMA protocol comprising 5 random surveys per day. We used craving, positive, and negative affect at the previous moment and predicted next moment "unknown" motive endorsement using a multilevel logistic regression. Results demonstrated a significant linear relationship between craving and "unknown" motive endorsement above and beyond the effects of positive and negative affect. Notably, the non-linear effects of positive and negative affect remained significant, but a non-linear craving term was not significant. Results suggest that craving, positive, and negative affect all play unique predictive roles in "unknown" motive endorsement, each with varying patterns. Future work should continue to expand upon the phenomenology unknown motives in larger samples.