"The prevalence of homelessness globally is estimated to be roughly 150 million individuals at any given time (Busch-Geertsema et al., 2016). In the UK, recent data from the Shelter organisation estimated that 320,000 people were homeless in 2019/2020 (Bramley & Fitzpatrick, 2018). Problematic drug use among this population has been extensively documented in the scientific literature (O'Flaherty et al., 2018; Paudyal et al., 2017; Van den Bree et al., 2009; Krupski et al., 2015; Linton et al., 2013; Narendorf et al., 2017). Homelessness and drug misuse often coexist, and the recorded prevalence of drug use among homeless individuals in different countries is consistently above the national average (Doran et al., 2018; Johnson & Chamberlain, 2008; Krupski et al., 2015). Although the high prevalence of traditional drugs has been extensively documented within the homeless population, NPS have become an increasing risk to this population, with particular concern regarding the use of synthetic cannabinoid receptor agonists (SCRAs) due to their underdefined toxic effects, difficulty in treating them and lack of confidence from clinicians (Sulaiman and MP, 2019; Thornton, 2018; Williams, 2017)."

Source

Coombs, T., Ginige, T., Van Calster, P. et al. New Psychoactive Substances in the Homeless Population: A Cross-Sectional Study in the United Kingdom. Int J Ment Health Addiction (2023). doi.org/10.1007/s11469-022-00988-7