Why do people use new psychoactive substances? Development of a new measurement tool in six European countries.

New psychoactive substances (NPS) pose a public health threat. Many studies have tried to identify the reasons of NPS use; however, none of them have so far used any standardised measures. The aim of this study was (i) to develop and cross-culturally validate the New Psychoactive Substance Use Motives Measure (NPSMM) and (ii) to compare motives of NPS use across countries and user types. Three subgroups (socially marginalised users, nightlife attendees and members of online communities) of NPS users ( Exploratory and confirmatory factor analysis resulted in a similar five-factor solution across most of the countries: coping, enhancement, social, conformity and expansion motives. Marginalised users scored higher on coping and conformity motives, nightlife groups showed higher endorsement of social motive, whereas online community users showed higher scores on expansion motives. Various types of NPS were also associated with different motives. NPS use motives might be associated with both the groups of users and the specific types of NPS being consumed. Expansion (psychedelics) and enhancement (stimulants) motives seemed to be linked to the chosen NPS product type, while coping, social and conformity motives were rather associated with user groups. NPSMM was found to be a valid instrument to measure NPS motives.