Psychosocial interventions can be helpful for adults experiencing homelessness.
Many people experiencing homelessness also face issues with problematic substance use and mental ill health, in addition to housing instability. Psychosocial interventions are a group of different approaches that are often used to reduce these issues. This review includes some evidence of whether these interventions work, as well as practice and policy recommendations. It also highlights the need for research to be conducted outside of the United States.
The review in brief
Psychosocial interventions work to reduce problematic substance use and mental ill health for adults experiencing homelessness. There is currently insufficient evidence to confirm that they are effective in decreasing housing instability. Individual psychosocial interventions can also be effective: cognitive behavioural therapy (CBT) reduces problematic substance use and motivational interviewing reduces mental ill health. It is unclear whether other psychosocial interventions work or not.
What is this review about?
Homelessness is often traumatic, with devastating cONSequences for those experiencing it. People experiencing homelessness face significant barriers such as stigma and discrimination when they try to access services, and often ‘fall through the cracks’ between different services. Homelessness is often associated with problematic substance use, mental ill health, offending behaviour, and being victims of crime, It is important to understand which interventions work best to reduce these issues and improve the lives of people experiencing homelessness. Psychosocial interventions are increasingly used to address some of these issues for people experiencing homelessness. This is a broad group of different interventions, which use psychological approaches to enable positive changes in thoughts, motivations, and behaviours. This review looked at whether these interventions worked to reduce problematic substance use (alcohol and/or drugs), mental ill health, and housing instability.
What is the aim of this review?
This Campbell systematic review examines existing evidence of the effects of psychosocial interventions on at least one of three outcomes (reducing problematic substance use, mental ill health, and/or housing instability). The review compares psychosocial interventions and other ways of delivering services. The review summarises results from 26 papers, all of which cover studies that were conducted in the United States and almost all of which were randomised controlled trials (RCTs). The authors of this review did not conduct any of the studies presented in the 26 included papers.
What are the main findings of this review?
We examined 898 individual papers to see if they evaluated psychosocial interventions, used with adults experiencing homelessness, in relation to at least one of the three outcomes of interest to us. From these 898 papers, we included 26 papers that covered 23 studies that met our criteria. This process was undertaken by two researchers independently, with a third researcher making final decisions. All of the included papers were from the United States and all but one were RCTs (a type of evaluation where people are randomly assigned to receive either the intervention of interest or a comparison service). The papers covered a number of different psychosocial interventions. We were able to find evidence about six interventions, including Brief Interventions, Brief Motivational Interventions, CBT, Contingency Management, Dialectical Behavioural Therapy, and Motivational Interviewing. We were not able to find evidence about other types of psychosocial interventions.
Do psychosocial interventions work for adults experiencing homelessness?
Yes, overall, psychosocial interventions do work better when compared to other services for adults experiencing homelessness.
Psychosocial interventions work overall in reducing problematic substance use when compared to other services. They also work in reducing mental ill health when compared to other services. But the evidence is less than clear about whether they work in reducing housing instability. This might be because there were only two studies, presented in three papers and all by the same lead author, that looked at the effect of these interventions on housing outcomes.
Which individual psychosocial interventions work, and for what outcomes?
CBT works better than other services in reducing problematic substance use for adults experiencing homelessness. Motivational Interviewing works better than other services in reducing mental ill health for adults experiencing homelessness.
Other results were less encouraging, as it is unclear whether the interventions work for other outcomes. There were non-significant effects (i.e., they could work better than other services, but there is also a chance that they work equally or less well) in relation to CBT and reducing mental ill health, motivational interviewing and reducing problematic substance use, and brief motivational interventions and reducing problematic substance use. There were no results about whether these six interventions reduced housing instability. There were no results about other types of psychosocial interventions on any of the three outcomes of interest to us.
What do the findings of this review mean?
Psychosocial interventions can help adults experiencing homelessness reduce problematic substance use and reduce mental ill health. Individual interventions including CBT and Motivational Interviewing can also work. But more research is needed about psychosocial interventions, particularly from outside of the United States.
How up-to-date is this review?
This review includes papers and studies published before August 2022.