New UCSF BHHI Report Examines the Relationship Between Homelessness and Drug Use

SAN FRANCISCO (March 19, 2025)—The University of California, San Francisco Benioff Homelessness and Housing Initiative (BHHI) today released a report that examines the issues of homelessness and behavioral health (substance use and mental health) and makes recommendations for policymakers and practitioners. 

“Homelessness and behavioral health problems are intertwined,” said Margot Kushel, MD, BHHI Director. “Complex behavioral needs, including substance and mental health problems, increase the risk of becoming homeless, and homelessness exacerbates these problems. Until people receive the housing and support that they need, there is a dire need to mitigate the harm that people experience, including the high risk of overdose and involvement in the criminal legal system.”

Jeff Olivet, Senior Advisor at the Harvard T.H. Chan School of Public Health’s Initiative on Health and Homelessness and former Executive Director of the U.S. Interagency Council on Homelessness, emphasized the urgency of addressing these challenges: “This new UCSF BHHI report makes clear that homelessness and behavioral health are inextricably linked — and that the solutions lie in expanding supportive housing, fully integrating health and housing systems, and investing in proven evidence-based approaches. Policymakers and communities across the country should take these findings seriously.”

The Behavioral Health and Homelessness Report is based on survey data and in-depth interviews from the 2023 California Statewide Study of People Experiencing Homelessness (CASPEH), the largest representative study of homelessness in the U.S. since the mid-1990s.

The full findings and recommendations from the Behavioral Health and Homelessness Report are available here.

KEY FINDINGS

• Nearly half (48%) met the criteria for having a complex behavioral health need, defined as either regular drug use, heavy regular alcohol use, hallucinations, or a recent psychiatric hospitalization.
• Thirty-five percent (35%) of CASPHEH participants reported regular illicit drug use during the prior six months, defined as use three times or more a week of either methamphetamines, non-prescribed opioids, or cocaine.
• Among people who used drugs regularly (three times a week or more), 42% reported that they began to use regularly after the first time they experienced homelessness.
• Methamphetamine was the most common drug used; 32% of adults experiencing homelessness reported regular methamphetamine use, 11% reported regular opioid use and 3% regular cocaine use.
• Twenty-eight percent (28%) of those with regular drug use or current heavy alcohol use reported wanting substance use treatment but being unable to access it during this episode of homelessness
• White people younger than 50 were the most likely to report regular illicit drug use (52%) and Black people under 50 were the least likely (20%).
• People with complex behavioral health needs were more than twice as likely (27% versus 12%) as those without to have entered their current experience of homelessness directly from an institutional setting (jail, prison, or inpatient behavioral health treatment setting).
• People with complex behavioral health needs were more likely to report unsheltered homelessness (89%) than those without complex behavioral health needs (68%).
• Like those without complex behavioral needs, people with complex behavioral health needs most frequently reported cost as a major barrier to housing (89% of those with complex needs and 90% of those without). 

The Report includes recommendations that policymakers and programs should consider to better support those experiencing behavioral health issues and homelessness.

The Behavioral Health and Homelessness Report is part of a series of reports based on this data, including the comprehensive study, reports on intimate partner violence and homelessness, racial equity and Black people experiencing homelessness, and older adults experiencing homelessness, and topic briefs on pregnancy and homelessness and unsheltered homelessness. 

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Media Contact: For more information or to schedule an interview with Margot Kushel, MD, UCSF BHHI Director, please email  OUUVzrqvn@hpfs.rqhude.fscu@aidemIHHB .

Citation: Dones, M., Espinoza, M., Smith, A., Perry, E., Dhatt, Z., Knight, KR., Kushel, M. (2025). Behavioral Health and Homelessness in the California Statewide Study of People Experiencing Homelessness. UCSF Benioff Homelessness and Housing Initiative.

We thank the California Health Care Foundation (CHCF) for supporting this work. A full list of partners and funders for the CASPEH study, from which these data are drawn, is available at homelessness.ucsf.edu/CASPEH.

About UCSF BHHI

The UCSF Benioff Homelessness and Housing Initiative provides accurate, timely policy-oriented research about homelessness for local, state, and national policymakers and practitioners. Funded by a generous gift from Marc and Lynne Benioff and based at the UCSF Center for Vulnerable Populations, UCSF BHHI is a trusted source for evidence-based practice, policy, and scalable solutions—turning evidence into action to prevent and end homelessness.