Keywords

Introduction

Among the homeless, there are high rates of substance use disorders, primarily alcohol and illicit drugs. Homeless individuals face unique challenges when engaging in treatment for substance use disorders, which likely contributes to the high rate of treatment failure observed among this population. Features of homelessness that correlate with increased rate of treatment relapse include unstable living environment and lack of social supports. For these reasons, understanding and addressing substance use disorders and homelessness can have a significant impact on the availability and delivery of care to this population and has the potential to improve outcomes.

Prevalence of Substance Use and Abuse Among Homeless

Determination of the prevalence of SUD among the homeless population is difficult and varies based on several factors, including inconsistent definitions of homelessness, population studied (youth v. elderly; male v. female), varied sampling strategies (structured interview v. self-report), and location of sample (telephone v. shelter v. hospital setting v. primary care clinic). However, the consistent finding is that substance abuse is more common among homeless than in those who are housed. The Substance Abuse and Mental Health Services Administration estimates that 38% of homeless people are dependent on alcohol and 26% abused other drugs [1]. Other studies have found that over a third of homeless individuals experience alcohol and drug problems [2]. In a recent survey of homeless adults aged 50 and older in California, nearly two-thirds had used at least one illicit drug in the previous 6 months and exhibited moderate severity symptoms [3]. A literature review on SUD among homeless from seven Western countries found that alcohol dependence affected 38% of the male samples (range of 9–58%) and drug dependence affected 24% of the total sample (range of 5–54%) [4].

The most common substance used by a national sample of homeless adults is tobacco. Nearly 75% smoke cigarettes [5]. This prevalence of tobacco use among homeless is four times that of the general US population. Not surprisingly, smoking-related deaths among homeless occur at twice the rate seen among housed persons and significantly contribute to the higher and younger mortality seen among the homeless [6].

Alcohol is the primary substance of abuse in nearly 49% of homeless who were admitted to a substance abuse treatment facility, followed by opioids (22%) and cocaine (14%) [7]. Crack cocaine use not only predicted greater homelessness at baseline; it also predicted greater homelessness within 6 months among those who were initially housed [8].

Of concern is the finding that over the past several decades, rates of substance abuse among homeless persons seem to be rising among both men and women, with the observed change mainly in illicit drug use [9, 10]. Further, when compared with people who are housed, those who are homeless have more severe substance use disorders [11]. An interesting finding is that substance-related presentations to an urban emergency department is highest at the beginning of the month and steadily declines thereafter [12]. This finding was stronger for patients with primary substance use disorders than for patients with other mental illness. This pattern closely corresponds to access to disposable income from federal disbursements, including social security, veterans pensions, and welfare.

Outcomes Associated with Homelessness and SUD

Substance abuse increases the risk that a person will become homeless, often through the inability to maintain professional obligations (i.e., work, school), and once that occurs, the likelihood of obtaining stable housing independently is significantly reduced. SUD disrupts relationships with social supports, including friends, family, and community members, leading to further social isolation. Additionally, they face greater obstacles in accessing general and preventive primary care services, as well as addiction treatment and support for recovery.

Use of substances is associated with significant morbidity and mortality among homeless persons. For those who are living on the streets, intoxication poses particular safety risks due to increased vulnerability to theft, assaults, rape, and arrests [13]. SUD can lead to increased risk for contracting communicable diseases (i.e., through shared needles usage, risky sexual behavior, poor hygiene, etc.), accidental deaths (through falls with subsequent subdural hematoma, overdose), and an overall deterioration of health [14]. A study that observed physical and mental health in homeless illicit drug users in Dublin, Ireland, found that “current and previous drug users were five times more likely than non-drug users to suffer from multi-morbidity and current drug users were 4 times more likely compared to never drug users to have a lower perceived quality of life” [15].

In the USA, studies have found higher mortality risks in homeless than in the general population, often from preventable causes [16]. O’Connell reviewed data from several studies and determined that homeless have a three to four higher mortality rate than the general population. A history of alcohol use or intravenous drug use further increased the risk by an odds ratio of 1.5. Homeless persons are at particular risk for drug overdoses [17] and suicidal thinking or attempts [18]. In a recent study, homeless adults with SUD were significantly more likely than those without SUD to have suicidal ideation [19]. More than two of every five opioid overdoses among homeless were due to opioids alone [20] (Table 12.1).

Table 12.1 Substance implicated in overdose deaths in homeless adults [20]
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Two-Way Relationship Between SUD and Homelessness

Substance use disorders are often cited as significant determinants of homelessness [21]. Addiction can lead to loss of job, disruption of social ties, and, for low-income persons, loss of housing [1]. Substances may be used to cope with problems; however, this leads to further employment instability and difficulty finding and keeping stable housing. In this model, alternatively referred to as the social selection or “drift down” hypothesis, homelessness is the result of the progressive social and economic resource losses associated with substance use disorders [22].

Alternatively, homelessness can lead to SUD. In this model, known as social adaptation or social causation, once homeless, the person may become increasingly more socially isolated and can begin to turn to a substance of abuse, such as alcohol or illicit drugs, to manage the stresses of homelessness. Some homeless individuals may use alcohol and drugs to be accepted in the homeless community [22]. As early as 1946, researchers estimated that one third of homeless people in their investigation became heavy drinkers as a consequence of homelessness and related factors [23]. In another study by the UK, 80% of respondents had initiated using at least one new substance since becoming homeless [24].

Comorbid Psychiatric Disorders in Homelessness and SUD

Psychiatric disorders commonly co-occur with substance use disorders among homeless. Homelessness is associated with more severe psychiatric symptoms and a higher number of prior admissions for mental illness [25]. Similarly, people with both SUD and mental illness have been reported to be at greater risk for homelessness due to the severity of their symptoms, denial of illness and/or need for treatment, refusal to engage in services, and use of multiple substances [26]. Regarding personality disorders, both Clusters A (paranoid, schizoid, and schizotypal) and C (avoidant, dependent, and obsessive-compulsive) are found more often among homeless [27]. Homeless persons with serious mental illness are more likely to experience violence (assault, rape, injury), exposure to the elements, and accidents and to have been exposed to trauma as children [28,29,30,31]. Post-traumatic stress disorder is thus highly prevalent among homeless, with 18–48% meeting current criteria for PTSD and between 35 and 52% meeting lifetime criteria [32]. PTSD rates are particularly high among homeless women. A recent study of 148 homeless women in 3 US cities found lifetime prevalence of PTSD to be 42.6% [33]. Nearly 75% of this sample also met criteria for at least one SUD.

Treatment Considerations

Homeless persons with SUD are very challenging to work with. Even if housed, the situation may not be stable, and they remain at high risk for a return to homelessness. Clinical understanding of the natural history of SUD has changed the way we think about treatment. The expected relapses and remissions linked to subsequent treatment episodes reframe SUD as a chronic disease better served by the Chronic Care Model (CCM) [34]. Addressing their needs consists of a multi-pronged approach, including outreach, screening, assessment, behavioral interventions, and psychopharmacologic assistance to successfully manage acute detoxification and, in some cases, medication-assisted interventions.

The clinician often should serve in the role of reminding the patient of his/her goals and reasons for desiring sobriety and permanent housing and to consistently offer hope, when the patient has difficulty seeing it for themselves. Abstinence and sobriety are very difficult to achieve and sustain. It is often helpful to think about success in measured steps: longer periods of sobriety between relapses, shorter periods of relapse before requests for detox/assistance, and gradual acceptance of need for treatment services.

The Chronic Care Model

Treatment for SUD has adapted the Chronic Care Model [34]. CCM is a comprehensive model which uses evidence-based system changes to meet the needs of growing number of people who have a specific chronic disease. Thus the first adaptation is to view SUD as chronic diseases that would benefit from comprehensive care. CCM traditionally has six components to affect functional and clinical outcomes associated with disease management (Table 12.2).

Table 12.2 Chronic Care Model adapted to care for SUD
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Programs which have successfully implemented the CCM strategically used well-trained addiction clinicians and/or clinical social workers for SUD chronic care [36]. Populations in which this health systems model has been successfully implemented have included homeless veterans [37, 38] and homeless women with alcohol use disorder [39], as well as housed low-income individuals with alcohol or opioid use disorder in primary care setting [35].

This model is successful in the treatment of SUD for several reasons. First, longitudinal care specifically addresses the chronic nature of SUD [40]. Second, integrating this multi-pronged care at primary care level addresses concerns regarding stigma and reaches out to the location where many individuals will initially present for treatment [41]. Lastly, this model has demonstrated effectiveness in sustaining recovery [42].

Outreach

Homeless persons may not be aware of the services available in the immediate area. Initial efforts at outreach should first address basic needs to better engage the patient. Information should be provided regarding how and where to obtain identification cards, local temporary shelters, food/soup kitchens, and places that are available to shower and do laundry. Additional services that may be helpful include where to access use of a computer or fax so that patients can apply for jobs, attend school and complete homework assignments, and also maintain the social contacts they may have. In addition, those persons who are disabled will also need information regarding applications for entitlements, including government assistance for income and housing subsidies.

Once basic needs are addressed and a trusting relationship has been established, information about local behavioral health and substance abuse treatment programs can be shared. One small sample of assertive outreach to homeless persons with SUD demonstrated success in 41% of the group entering treatment [43].

Screening and Assessment of SUD

Adequate assessment tools are needed to identify the needs of homeless individuals with SUD, who experience unique circumstances and are particularly vulnerable for sensory loss, comorbid medical conditions, and, in some cases, cognitive impairment [44]. Access to appropriate assessments can further the development of preventive measures and treatment practices, which can yield improved health outcomes. Assessments should be customized and constructed specifically for the homeless. For example, while there are many assessments that screen for sleep quality or nutrition in the general population, these assessments lose validity among the homeless, given that this population often does not have a bed in which to sleep or access to food preparation and storage appliances (i.e., refrigerators).

The following tools have been validated for use that takes into account the specific circumstances of homelessness:

  • Addiction Severity Index (ASI) [45]

  • Beck Depression Inventory (BDI II) [46]

  • Brain Injury Screening Questionnaire (BISQ) [47]

  • Brief Instrumental Functioning Scale [48]

  • Colorado Coalition for the Homeless Consumer Outcome Scale [49]

  • Delighted-Terrible Faces Scale (DTFS) [50]

  • Rural Homelessness Interview Schedule [51]

  • Life Fulfilment Scale (LFS) [52]

  • Nottingham Health Profile [53]

  • Short-Form Survey 12 (SF-12) [54] and/or Short-Form Survey 36 (SF-36) [55]

  • World Health Organization Quality of Life 100 (WHOQoL 100) [56] and/or World Health Organization Quality of Life BREF (WHOQoL-BREF) [57]

Behavioral Interventions

There are a wide range of evidence-based treatments that have been studied and found to be effective in homeless with SUD. Examples include motivational interviewing, assertive community treatment, intensive case management, 12-step programs, and contingency management. Among treatment programs that offer these services, six core principles that facilitate the reduction of substance use disorders among people who are homeless have been identified and are listed in Table 12.3 [58]. (Table 12.3).

Table 12.3 Core principles associated with reduction in substance use disorders among homeless persons
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Motivational interviewing (MI) has an extensive evidence base and wide applicability [59]. This modality can be used to facilitate acceptance of substance abuse treatment, transition to permanent and supportive housing, and case management services [60]. MI typically starts with an evaluation of the addictive behavior, its consequences, and the social and personal context of use. Personalized feedback is offered and guided by reflective listening, resistance reduction, and avoidance of arguing with the client. Direct advice is offered which challenges the client’s assumptions but leaves the decision and responsibility to the client. Within the adult population, brief motivational interviewing is shown to decrease alcohol use, drug use, and smoking.

Intensive case management services can address the unique and extensive needs of homeless persons. An advantage of intensive case management is that the case manager can serve to coordinate services that are often fragmented and delivered through many providers and agencies. An added advantage is that the case manager can serve to navigate multiple systems of care with and for the homeless person, in a way that he/she might not be able to do for themselves.

A shelter-based assertive community treatment (ACT) intervention in which homeless persons worked with a consistent social worker and psychiatrist was more likely to enter treatment than those who received standard treatment with the available provider [61]. This intervention resulted in 51% of participants engaging with a substance abuse program versus only 13% of the standard group. A related randomized trial compared ACT (a client-provider ratio of 1:15 or 1:10) with an integrated intensive clinical case management approach (ratio of 1:25) [62]. Both interventions were equally successful with approximately 1/3 of participants in each group achieving remission.

Group-based interventions demonstrate high levels of success in this population. A recent randomized clinical trial examined alcohol use among young homeless adults [63]. The treatment intervention used group processes including facilitator behavior, participant change talk (CT), and sustain talk (ST). Participants were followed for 3 months. Group CT was associated with decreased likelihood of being a heavy drinker at the 3-month follow-up. Peer groups and consumer-run drop-in centers are also valuable resources for people who are homeless, particularly if those centers also provide core services, such as shower and laundry facilities, and access to computers and telephones [64].

Alcoholics Anonymous (AA) is an effective group intervention for homeless persons with SUD due to affordability, non-intrusiveness, and ease of attendance. Additional benefits include the mentorship and fellowship seen which creates a socially supportive, non-judgmental environment [65]. The phases of Alcoholics Anonymous participation and recovery have been described as follows: “hitting bottom, first stepping, making a commitment, accepting your problem, telling your story, and doing twelfth step work” [66]. Narcotics Anonymous has adapted the AA model but replaces “alcohol” with addiction and serves to assist anyone who wishes to obtain sobriety from any substance of abuse [67].

AA and NA, however, may not be helpful for all homeless persons and, often, are utilized after an individual has secured housing. AA and NA emphasize prioritizing recovery and sobriety above everything else. However, when an individual has very basic unmet needs, such as securing shelter or food, these become the priorities [66]. Additionally, chronically homeless persons with SUD are at high risk for remaining homeless, and thus delays in being able to find and maintain quality housing [68]. Studies suggest that having economic and housing stability is almost a requirement to maintaining sobriety [69]. This in part has led to the evidence-based model of Housing First, in which abstinence is not a requirement for program entry [70]. In fact, one study found an 80% housing retention rate among persons who were chronically homeless, with SUD and a co-occurring mental health diagnosis when a Housing First approach was used [71].

Faith-based services are also available to address the needs of homeless persons with SUD. One study found that participation in religious-oriented programs did not significantly change the individual’s level of religiosity or religious participation [72]. However, greater religious participation was associated with positive outcomes in housing, mental health, substance use, and overall quality of life.

Contingency management programs utilize behavioral psychology principles. Clients earn vouchers or obtain prizes or privileges as they achieve sobriety and maintain abstinence or achieve other behavioral change goals [73]. This type of a program has consistently shown higher rates of abstinence among homeless persons with cocaine use disorders [74] and reductions in risky behaviors, including quantity of substance use [75].

Medications for Substance Use Disorders

Access to medication-assisted treatments and adherence is very difficult for homeless individuals. The barriers include understanding medication instructions, keeping to a schedule, and being able to afford and store medication [76]. In addition, some persons are reluctant to take medications that may cause sedation as they have a need to be alert to potential assaults. As a result, studies have found that being homeless was associated with the lowest rates of medication adherence [77]. This may also play a role in the high use of hospital services.

Homeless persons with substance use disorders are at high risk for overdoses and related mortality [78]. A recent study found that half of opioid misusers had personally experienced an overdose and most of the sample had witnessed someone else’s overdose [79]. Given the current epidemic of opioid overdose deaths, there is an urgent need for more widespread access to naloxone.

Naloxone is a short-acting prescription opioid antagonist, which actively displaces heroin and other opioid drugs from the mu opioid receptor. It rapidly reverses the effects of opioids and, in the event of overdose, is lifesaving, with rapid return of consciousness and independent breathing. Clinically, this is true whether the overdose is of an illicit drug, such as heroin, or a prescription opioid medication, obtained via prescription or diversion. Emergency naloxone kits, known as “take-home naloxone,” are available in the USA, and although available in injectable and nasal spray forms, the nasal spray is more cost effective (approximately $30 for a twin pack) [80]. These kits can now be prescribed as part of the comprehensive care of persons who have opioid use disorders.

Studies have found that lay public friends and family members are highly willing to provide emergency care while waiting for traditional first responders to arrive [81]. Since 2017, 49 states and the District of Columbia legally allow pharmacists to dispense naloxone [82]. Naloxone should be prescribed to any person who is using heroin or other opioid products and instructed in its use [83]. These take-home kits have significantly increased naloxone availability [84].

Education should also be provided to the person’s identified social contacts, friends, and/or family members in order to improve the likelihood that naloxone will be used and effective. Further, use of naloxone has been implemented in homeless health clinics and shelters [85, 86].

Office-based buprenorphine treatment for opioid disorders has been found to be as effective for homeless persons as it is for housed persons, but they required more clinical support during the initial month of treatment [87].

Settings of Care

Homeless persons use emergency department services much more frequently than do people who are housed for several reasons [88]. Homeless persons may have more severe disease, lack access to other forms of care, and often have medical comorbidities that may require evaluation and treatment. One model to evaluate and treat these persons while reducing the need for psychiatric hospitalization is the use of Mobile Crisis Teams [89]. People who are homeless also are more likely to be admitted for substance-related disorders than those who are housed [90]. They have longer lengths of stay once admitted, higher costs associated with the admission, and higher readmission rates [91, 92]. They also are more likely to enter a detoxification program [93]. However, detoxification alone is often ineffective with relapse rates varying by substance of abuse but range 60% for alcohol [94], 60–80% for cocaine [95], and 65–80% for opioid dependence [96].

For these reasons, adequate discharge planning is critical. Short-term (2–6 weeks) transition residential programs, when available, have been associated with significantly lower relapse rates [97]. Residential treatment can also improve social skills and enhance a sense of community and social connectedness. These programs can successfully reduce depressive symptoms, as well increase the person’s ability to tolerate distress. The ability to tolerate distress has been associated with better outcomes among individuals with addictive behaviors [98].

Making housing continent upon substance abstinence produces higher rates of drug abstinence than non-contingent housing [74, 99]. Recent studies have added reinforcement-based treatment (RBT) to abstinence contingency housing [100]. RBT is an intensive day treatment program which consists of cognitive behavioral group therapy, abstinence-contingent recreational activities, vocational assistance, individual counseling, and housing support. The addition of RBT further improves treatment outcomes [101, 102].

Conclusion

Working with homeless individuals who also have substance use disorders is challenging. Based on available data, the most effective models of care address basic core needs first, particularly secure housing. The management of substance use disorders is best understood through the chronic care model of illness. Establishing trust with a consistent treatment team is needed, and through the use of motivational interviewing and other behavioral strategies, the person will not only be more likely to engage in substance abuse services but also more likely to sustain sobriety and recovery. Encouragement of participation in 12-step programs and faith-based groups will further a sense of community and facilitate the establishment of new social supports. When the person has co-occurring psychiatric and medical conditions, additional resources that can evaluate and treat acute conditions and offer preventive services will need to be coordinated. Because of the magnitude and complexity of services that are needed, the ideal mechanism is to provide a “one-stop shop,” in which all of these services are offered in a single location. Clinical, social, and core services could be offered, as discussed below.

The clinical services should offer primary care, mental health, and substance use services at the same location. The substance use services would ideally include peer support counseling, group, and 12-step options, preferably with contingency and/or reinforcement approaches. Naloxone should be offered as part of comprehensive treatment to any person at risk for opioid overdose.

The social services would facilitate education regarding criteria for various government aid programs, including housing options (transitional, residential programming, subsidized, etc.), how to obtain needed documents (birth certificate, DD-214 for veterans, identification card, etc.), and how to apply for those programs. The social services would also include information regarding educational and vocational programs and, if the person is disabled, application for disability programs.

Core services would include space for showers, laundry facilities, computers, fax machine and telephone access, non-denominational chapel or meditation room, and emergency food pantry. Through this “one-stop shop” model, care is delivered in a patient-centered and coordinated fashion, which ultimately provides improved outcomes for the patient and less cost for society as a whole.