The presence of homeless people continues a trend that began in the early 1980s. The number of homeless individuals has increased, and the demographic profile of this population has changed. Late in the twentieth and early twenty-first century, the “traditional” homeless, predominantly composed of single males, were joined by new groups of homeless, including families (Wright, Rubin, and Devine, 1998). At the time of this writing, the global recession including the mortgage foreclosure crisis has added to an increase in family homelessness (National Alliance to End Homelessness, 2009; Sermons and Henry, 2009).

The purpose of this chapter is to describe the scope of this problem. The chapter presents definitions, prevalence, and demographic characteristics of homelessness; analyzes factors that contribute to homelessness; and describes the health status of various aggregates of the homeless population. The chapter also addresses issues of health care access, explores conceptual approaches to understanding health among the homeless, and proposes community health nursing strategies for the primary, secondary, and tertiary prevention of homelessness and its associated problems.

Many meanings exist for the term homeless. Official governmental agencies, the professional literature, and lay people use the term in various ways. Some view the term home as a synonym for the place where an individual’s family resides. People without family ties, such as those living in single-room–occupancy hotels without family contacts, are, from this perspective, “homeless” (Jencks, 1995; Smith and Smith, 2001). However, government agencies’ definitions of homeless focus on living quarters, or more specifically sleeping places of individuals, and not family ties. Official governmental reports continue to use the statutory definition put forth by the federal McKinney-Vento Homeless Assistance Act, which was originally authorized in 1987 and defines homeless in two different sections.

One section defines homeless as the following (U.S. Department of Housing and Urban Development, 2007):

The education subtitle of the McKinney-Vento Homeless Education Assistance Improvements Act of 2001 as amended by the No Child Left Behind Act of 2001 (U.S. Department of Education, 2004) contains definitions that relate to children and youth.

In addition to these statutory definitions of homelessness, federal agencies administratively define another category of homeless persons—the chronically homeless individual. According to the federal government, a chronically homeless person is “an unaccompanied homeless individual with a disabling condition who has either been continuously homeless for a year or has had at least four (4) episodes of homelessness in the past three (3) years” (U.S. Department of Health and Human Services, 2003b).

Other meanings of homeless are found in the professional literature, where individuals or families are frequently categorized according to the duration and number of episodes of homelessness. Those experiencing a relatively infrequent and short duration may be designated as crisis, first time, transitionally, or temporarily homeless; those who experience longer and more frequent periods are referred to as episodically or intermittently homeless individuals; and families who are homeless for a year or with more episodes over several years are classified as chronically homeless (Burt, Aron, and Lee, 2001; Kuhn and Culhane, 1998; Lambert and Caces, 1995; U.S. Department of Health and Human Services, 2003a, 2003b).

However, many Americans use another definition of homelessness. This colloquial usage reflects the more traditional view of the homeless as the shabbily dressed people they notice in public places during the day (O’Flaherty, 1996). Homeless advocates argue that it is also important to consider those who are poor and tenuously housed. This includes those who are without their own shelter but have “doubled up” with a family member or friend. An estimate of this population is difficult at best. Definitions of homelessness vary and consequently give rise to many interpretations and considerable confusion regarding research findings and policy implications (Shinn and Baumohl, 1999).

Based on data collected during the January 2007 1-night counts, the third AHAR report identifies the following sheltered homeless subpopulations: domestic violence victims, persons with serious mental illness, unaccompanied youth, veterans, persons with substance abuse problems and persons living with human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS). Among all sheltered homeless persons, 13% were victims of domestic violence and 28% were persons with serious mental illness. Unaccompanied youth comprised 2% of the total sheltered homeless population. Veterans and persons with substance abuse problems comprised 15% and 39% respectively of all sheltered homeless adults. Persons living with HIV/AIDS represented 4% of sheltered adults and unaccompanied youth (HUD, Office of Community Planning and Development, 2008).

In addition to the information based on the PIT January 2007 count, the third AHAR includes descriptions of homeless people who were sheltered at some time during October 2006 to September 2007. The report uses two categories of homeless persons: individual and family. Individuals accounted for 70% of the sheltered homeless population. Among this group, 69% were men, 25% were women, and 5% were unaccompanied youth. Individuals whose ages ranged from 31 to 50 years comprised 55% of the sheltered homeless individual population as compared with 24% of nonhomeless persons living alone in poverty. African Americans represented 33% of the sheltered individuals, a larger number compared with 18% of nonhomeless poverty population (HUD, Office of Community Planning and Development, 2008).

Presented next are the characteristics of sheltered family members (composed of at least one adult and one child). Of the total number of people in sheltered homeless families, children are 62%; adults are 38%. Women account for 82% of adult members, which is a larger percentage than the 67% of women in poor families. Adults in homeless families are younger than the adults in poor families, as 55% of homeless adult family members are between 18 and 30 years of age in contrast to 42% of adults in nonhomeless poor families. Sheltered homeless children are young, as 87% are under 12 years of age; more than half (51%) are under 6 years of age. African Americans make up 55% of the sheltered homeless population compared with 26% of nonhomeless poor (HUD, Office of Community Planning and Development, 2008).

This section has presented the federal definition of homelessness, a discussion of the challenges in obtaining a count of homeless populations, and a brief outline of selected demographic characteristics. A discussion of factors contributing to homelessness follows.

Factors contributing to the shortages include market forces that inhibit the private housing sector’s production of affordable rental housing, decreases in the federal government’s spending on assisted housing for low-income families, and the increasing inequality of incomes among groups within the larger population. The foreclosure crisis that began in 2007 has exacerbated the obstacles that people with low incomes face in obtaining affordable housing (Khadduri, 2008; Rice and Sard, 2009; HUD, Office of Policy Development and Research, 2007; Wardrip, Pelletiere, and Crowley, 2009).

Burt and colleagues, more than 10 years ago, documented that insufficient incomes and lack of employment prevented people from leaving homelessness (Burt et al., 2001). The U.S. Census Bureau’s report (DeNavas-Walt, Proctor, and Smith, 2008) reveals that, in 2000, the real median household income was $50,557 (adjusted to reflect 2007 dollars); in 2007 it was $50,223. Although the 2007 level reflects an increase compared with 2005 and 2006 levels, it is still less than the 2000 level. During the same period, 2000-2007, both the number of people in poverty and the poverty rate increased. Overall, the percentage of people living below the poverty line increased from 11.3% in 2000 to 12.7% in 2007, and during this same period, the number increased from 31.5 million to 37.0 million. The poverty rate among children younger than 18 years increased from 16.2% to 18.0% between 2000 and 2007. Moreover, in 2007, among the poor, 41.8% were in extreme poverty—classified as those having an income below half of the poverty line (DeNavas-Walt et al., 2008).

As a consequence of the shortage of affordable housing and insufficient income, an increasing number of low-income people end up paying much more than they can afford for rent. In many areas of the country, wages needed to afford housing are three to five times higher than the federal minimum wage of $7.25 (as of July 2009) per hour. This increase was the last increase of a three-step process. The wage first increased in July 2007 from the previous $5.15 per hour, which had been in effect since 1997; the second increase, to $6.55, occurred in July 2008 (U.S. Department of Labor, Employment Standards Administration, Wage and Hour Division, 2007). Paying too much of their income for rent leaves low-income people without adequate resources for other necessities, such as food, clothing, and health care, and increases the risk of homelessness (Children’s Defense Fund, 2008).

What the two groups have in common is the need for affordable health care, that is, health care in its broadest sense as outlined by the World Health Organization (WHO) (1948). Unfortunately, the proportion and number of people in the general population without health insurance increased during the period 2000-2007. In 2000, 13.7% (38.4 million) were not covered by health insurance; in 2007, 15.3% (45.7 million) were not covered. Among those whose incomes are below federal poverty levels, 24.5% were without health insurance in 2007. Among homeless clients receiving health care services, the rates of uninsured are even higher than among the nonhomeless poor (Kidder, Wolitski, Campsmith et al., 2007; Pearson, Bruggman, and Haukoos, 2007). Consequently, lack of health insurance is a significant factor in preventing people from leaving homelessness and may, indeed, be a major risk factor for homelessness. A serious illness or disability can lead to a downward spiral into homelessness as a result of job loss, use of savings to pay for care, and inability to pay rent (Burt et al., 2001; DeNavas-Walt et al., 2008).

The three broad factors contributing to homelessness—shortage of affordable housing, insufficient income, and scarcity of supportive services—are conditions in society. Singularly and more important, the interaction among these factors has serious consequences for low-income people. These conditions potentiate the vulnerability factors found among certain individuals and families and increase the probability of homelessness.

From a historical perspective, much of the earliest information on the health status of men was provided by data from the National Health Care for the Homeless Program, an initiative funded by the Robert Wood Johnson Foundation and the Pew Charitable Trust Fund in the late 1980s. Although dated, these data nevertheless stand as major sources of information on the health status of the homeless population (Institute of Medicine, 1988; Wright, 1990). The more recent reports cited in the following sections substantiate this earlier report.

Homeless men experience physical health problems, both acute and chronic, at higher rates than men in the general population. Acute physical health problems occurring at higher rates in homeless men include respiratory infections, trauma, and skin disorders (Bargh, Hoch, Hwang et al., 2007; Bucher, Brickner, and Vincent, 2006; Hwang, Colantonio, Chiu et al., 2008). Chronic disorders including hypertension, musculoskeletal disorders, diabetes, respiratory problems (asthma, chronic bronchitis, emphysema), neurological disorders including seizures, and poor dentition are also more prevalent among homeless populations (Schanzer, Dominguez, Shrout et al., 2007; Zlotnick and Zerger, 2009). In addition, HIV and AIDS, tuberculosis, hepatitis C, and sexually transmitted diseases (STDs) occur at higher rates in homeless men than in the general population. (Kidder et al., 2007; U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, 2008).

Many of these acute and chronic conditions are exacerbated by alcoholism, which occurs more frequently among homeless than nonhomeless men; alcoholism may be the single most prevalent health problem among the homeless. Likewise, serious mental illnesses occur more frequently among the homeless than in the general population. In addition, minor emotional problems (e.g., personality disorders) are also more frequent among homeless than nonhomeless men. Drug abuse, like alcohol abuse, occurs more frequently among the homeless, and considerable overlap of alcohol and drug abuse exists. Men are more likely than women to report alcohol abuse (Eyrich-Garg, Cacciola, Carise et al., 2008; Fazel, Khosla, Doll et al., 2008; Goldstein, Luther, Jacoby et al., 2008; Greenberg and Rosenheck, 2008a, 2008b; Padgett, Henwood, Abrams, et al., 2008).

Studies comparing homeless and housed poor people indicate that homeless adults are more likely to be male and have veteran status than the housed poor. Homeless adults are more likely to be unemployed, or if employed, the job is temporary or at a low wage and without benefits. Consequently, their income is insufficient to maintain housing costs. Although a lack of monetary resources is a variable related directly to becoming and remaining homeless, additional deficits in social resources contribute to the condition. Many of the homeless have relied on social support from families and friends to provide housing. Homelessness results when both monetary resources and social support are exhausted (National Coalition for the Homeless, 2008).

The National Survey of Homeless Assistance Providers and Clients (NSHAPC) has identified the following three subgroups among women experiencing homelessness: 38% have a minor child, 47% are by themselves, and 15% are with another person/not a minor child (“other clients”). Women from all three groups report health and nutrition needs that far exceed those of women in the general population. Women with minor children and single women are more likely to use shelters and less likely to sleep on the streets; women designated as “other clients” are the least likely to receive services. The latter are the most reclusive of the three subgroups—generally avoiding shelters and soup kitchens (Burt et al., 2001).

An accumulation of research evidence indicates that when compared with men, single women report more stressful life events, foster care as children, intimate partner violence as adults, and hospitalizations for psychiatric problems (Caton, Wilkins, and Anderson, 2007). Homeless women have higher rates of pregnancy, including unintended pregnancy, than their housed counterparts, and researchers have demonstrated that the severity of homelessness increases the likelihood of preterm births and low-birth-weight infants. Although increased access to prenatal care may improve the health of pregnant women, preventing homelessness in the first place is even more critical for birth outcomes, as women bring to pregnancy stressors that have a cumulative effect over the life course for reproductive health (Gelberg, Lu, Leake et al., 2008; Stein, Lu, and Gelberg, 2000).

In the 1990s, research clearly documented the extraordinary histories of violence, from childhood through adulthood, among women experiencing homelessness (Anderson, 1996; Bassuk, Buckner, Weinreb et al., 1997; Bassuk, Melnick, and Browne, 1998). Bassuk, Weinreb, Buckner, and colleagues (1996) reported that an estimated 92% of homeless women have experienced physical or sexual assault sometime in their lives. Researchers continue to document rape and other assaults among homeless women. Clearly, sexual assaults are associated with worse physical and mental health outcomes including use/abuse of alcohol and other drugs (Austin, Andersen, and Gelberg, 2008; Wenzel, Leake, and Gelberg, 2000). As may be expected, women living in unsheltered locations on the street have increased risk for victimization over women living in shelters. Unsheltered women also have greater odds of having multiple sexual partners and are less likely to utilize health services. Other factors that increase risk of physical and sexual victimization include history of mental illness, substance use/abuse, and engaging in survival strategies including selling sex and drugs (Nyamathi, Leake, and Gelberg, 2000; Wenzel et al., 2000). The Welfare Reform Act has impacted women’s homelessness in a variety of ways. Some stay in abusive relationships because of anticipated difficulty in accessing Temporary Aid to Needy Families (TANF) under this legislation. Others who do access TANF find it difficult to manage small children and fulfill work obligations: “exempting battered homeless women from participating in welfare-to-work activities exists in principle but for many women…does not exist in reality” (Roschelle, 2008). In addition, researchers report workplace violence in the lives of women who are homeless. Many of the women are reluctant either to report the violence or to leave the job because of financial needs (Anderson, 2008).

Social support influences women’s physical and mental well-being and their ability to access health services. Women who are homeless report a disconnectedness beginning in childhood that continues in adult life (Anderson, 1996). As adults, they score lower than their housed counterparts on measures of social support, as well as intimacy and reciprocity (Anderson and Rayens, 2004). They have fewer persons in their social networks, and these persons often experience similar emotional distress and have high-risk behaviors (Bassuk et al., 1996; Nyamathi, Flaskerud, and Leake, 1997). Women who have substance nonusers in their social support networks report better psychosocial status and increased health services utilization than those who have only substance users (Nyamathi, Leake, and Keenan et al., 2000).

It is impossible to separate women who are homeless from the context in which they live. Promoting lasting change in their lives requires not only addressing specific physical and mental health needs, but imbedding programs into their particular communities and assuming that women may need programs for a long term (Smyth, Goodman, and Glenn, 2006). Others suggest that because of the high numbers of women reporting histories of foster placement as children, as well as exposure to violence as both children and adults, assistance requires gender-specific interventions; pointing to the large numbers of women who have lost custody of their children in this aggregate, they also advocate programs that support and preserve families (Caton et al., 2007).

Finally, women who are homeless have an increased risk for incarceration. Incarceration risk is related to the public nature of homelessness and the likelihood of arrest for misdemeanors and other minor crimes. Shelters, jails, and prisons have become part of an “institutional circuit” that houses people, replacing more stable, community-based living situations (Caton et al., 2007; Hatton and Fisher, 2008; Metraux, Caternia, and Cho, 2007). Moreover, access to housing upon release to the community is a key predictor for decreasing recidivism among formerly incarcerated women (Freudenberg, Daniels, Crum et al., 2005).

Over a decade ago, Dr. Ellen Bassuk, president of the National Center on Family Homelessness, summarized the health-related problems from which homeless women suffer. They do not differ from the problems that impede many women in the United States, she argued, although their problems are likely to be more intense, frequent, and apt to occur in concert. Often, homeless women have limited education, limited earning power, and fragmented support networks. Trapped by a lack of economic and social opportunities, homeless women profoundly experience society’s inequities (Bassuk, 1993).

At the national level, the National Alliance to End Homelessness reported that the number of homeless families with children decreased between 2005 and 2007 (Sermons and Henry, 2009). In contrast, the National Center on Family Homelessness (2009), reported that the extent of child homelessness was worsening. Differences in the two accounts are mainly due to the use of two different definitions of homelessness. As indicated in a previous section of this chapter, the statutes and regulations governing HUD define homelessness more narrowly than those that govern the Department of Education (Vissing and Hudson, 2008). Whether the decreasing trends noted by the report using the HUD definition will continue is questionable, given the economic and housing crisis that began in 2007 (Duffield and Lovell, 2008). An overview of studies that provide information about homeless children’s health status follows. Included is information about broad aspects of the health of homeless children—physical and mental health and educational attainment.

In an extensive review of studies of homeless children, Buckner (2008) divided the research according to two periods: those published before and since 1991. He also noted whether the studies included comparisons of homeless children with housed poor children and/or the general population of children. The earlier studies conducted in the 1980s when family homelessness was emerging as a national problem were mainly descriptive, indicating the homeless children’s characteristics and needs. Later studies used more sophisticated research and statistical methods and provided answers to more complex questions.

Studies comparing homeless children with children located in the general population report that homeless children are more apt to experience physical health problems including asthma, iron deficiency, anemia, and obesity. Homeless children experience higher rates of mental health problems, including behavior problems and developmental delays, than rates reported for children in the general population (Grant, Shapiro, Joseph et al., 2007; Rog and Buckner, 2007; Shinn, Schteingart, Williams et al., 2008; Yu, North, LaVesser et al., 2008).

The previously outlined physical, mental, and developmental problems interact and adversely affect homeless children’s educational achievement on standardized tests covering reading, language usage, and/or mathematics. Missing days of school because of family mobility, homeless children are more likely than other children to repeat grades. Homeless children may lack resources for clothing and school supplies and access to facilities for personal hygiene maintenance. As a consequence, they may be at risk of nonacceptance or teasing by other students, thereby compounding the effects of their physical and mental problems (Duffield and Lovell, 2008; Dworsky, 2008; Obradovic, Long, Cutulia et al., 2009).

Although homeless children had higher rates of physical, mental health and behavior, and educational problems than children in the general population, when compared with poor but housed children, the rates were similar. In other words, the difference in housing status was not a contributing factor. Other authors report that there are significant differences within the population of homeless children. There is a subpopulation of homeless children that is doing well, while another subpopulation is experiencing multiple problems (Huntington, Buckner, and Bassuk, 2008; Obradovic et al., 2009).

Studies, policies, and programs related to homeless adolescents and youth use varying ages and overlapping categorical descriptors. Ages may range from 13 to 25 years. Categories used in studies and reports include runaway, throwaway, street, and system adolescent and/or youth. Runaways have left home without permission; throwaways have been forced out of the home; street adolescents and youth live primarily on the street; system adolescents and youth have been wards of the state (foster care, juvenile justice system) (Burt, 2007; Fernandes, 2007; Slesnick, Dashora, Letcher et al., 2009).

As indicated by several substantial reports and reviews of studies, adolescents and youth from all sectors of society engage in health-risk behaviors that result in serious health problems (Centers for Disease Control and Prevention, 2008). These problems include unintended pregnancy, STDs (including HIV/AIDS), alcohol and drug abuse, depression, and suicide. For the most part, these problems are related to risk-taking behaviors. However, homeless adolescents experience these problems at higher rates than the general adolescent population (Burt, 2007; National Research Council and Institute of Medicine, 2009; Toro, Dworsky, and Fowler, 2007; Zerger, Strehlow, and Gundlapalli, 2008).

Homeless adolescents experience STDs, physical and sexual abuse, skin disorders, anemia, drug and alcohol abuse, and unintentional injuries at higher rates than adolescents in the general population. Depression, suicidal ideation, and disorders of behavior, personality, or thought also occur at higher rates among homeless adolescents. Family disruption, school failures, prostitution or “survival sex,” and involvement with the legal system indicate that homeless adolescents’ social health is severely compromised (Burt, 2007; Busen and Engebretson, 2008; National Research Council and Institute of Medicine, 2009; Rew, Grady, Whittaker et al., 2008; Rew, Rochlen, and Murphey, 2008; Tevendale, Lightfoot, and Slocum, 2009; Toro et al., 2007).

Homeless adolescents and youth who are pregnant, engage in prostitution, or identify themselves as gay, lesbian, bisexual, or transgender experience more health problems than other homeless adolescents. Pregnant homeless adolescents and youth have more severe mental health problems and use alcohol and drugs more than nonpregnant homeless peers. Not surprisingly, they have higher rates of negative pregnancy outcomes than nonhomeless adolescents and youth (National Research Council and Institute of Medicine, 2009; Rew et al., 2008).

Runaway or homeless adolescents and youth, both female and male, make up a large percentage of all youth involved in prostitution. Many become involved because they need money to meet subsistence needs, which is the source of the term “survival sex.” They are more likely to have serious mental health problems and to be actively suicidal. Alcohol and drug use occurs at higher rates among this group than among homeless adolescents and youth not engaged in prostitution. Those involved in prostitution are more likely to report histories of physical and sexual abuse (Fernandes, 2007; Molino, 2007; National Research Council and Institute of Medicine, 2009).

Rates of attempted suicide are higher among gay homeless adolescents and youth. A large majority of males involved in survival sex identify themselves as gay or bisexual. Many of these young people are on the streets because of effects of homophobia and prejudice. Facing problems similar to those of other homeless adolescents and youth, the gay-identified face an additional set of problems as a result of others rejecting them because of their sexual orientation (National Research Council and Institute of Medicine, 2009).

Adolescents and youth in the general population are at risk, those who are homeless are at even higher risk, and the special subpopulations of adolescents and youth—including those who are gay-identified, those who are pregnant, and those who are practicing survival sex—are particularly vulnerable. Health for many of these groups is severely jeopardized.

In the 1980s, much discussion ensued about the “old homeless” and the “new homeless”—a situation whereby young families with children joined the “homeless population” previously composed of mostly single men with substance use disorders living on the streets (Rossi, 1990). Many thought the improved economic conditions of the 1990s would eventually eradicate this problem. Yet, family homelessness persists and has actually worsened in recent years. Research has shown that women heading homeless families in 2003 reported more physical health problems, major depressive illness, and posttraumatic stress disorder than women in 1993 (Weinreb, Buckner, Williams et al., 2006).

In 2008, when the U.S. Conference of Mayors released its annual report on hunger and homelessness, the Task Force emphasized the increased risk for hunger and homelessness among the nation’s working families because of the weak economy and the high cost of food and fuel (U.S. Conference of Mayors, 2008b). More specific causes of family homelessness identified in the report were lack of affordable housing (72%), poverty (52%), unemployment (44%), low-paying jobs (36%), domestic violence (28%), family disputes (20%), mental illness (12%), and substance abuse (12%). Of the twenty-two major U.S. cities responding to the Mayors’ annual survey, sixteen cities reported an increase in family homelessness, two reported a decrease, and four cities had no change (U.S. Conference of Mayors, 2008a).

The Mayors’ report indicates that families experiencing homelessness are less likely to be living on the street than other homeless populations, with twenty-three cities reporting that, on an average night, 543 of the persons homeless in families were on the streets, 9930 were in emergency shelters, 12,862 in transitional housing, and 10,710 in permanent housing. The average stays in these settings were 69 days (emergency shelter), 175 (transitional housing), and 556 (permanent supportive housing). The report warns that because families without housing usually double up with others before using shelters, the data probably do not reflect the actual level of housing need for families.

A systematic review of the research on homelessness concludes that families comprise approximately 34% of the homeless population; are frequently headed by single women with young, preschool children; and disproportionately represent ethnic minority groups. Families are commonly separated when they become homeless; shelters may not allow male children; and children may go to live with other family members or friends. Mothers report poorer mental and physical health than their domiciled counterparts, and they have incomes significantly below the federal poverty level. Without subsidies, their incomes are too low to obtain housing. Social networks have shown some protection from homelessness for poor families, but networks characterized by interpersonal conflict increase a family’s risk for homelessness. This systematic research review concludes with recommendations that include targeting families at imminent risk of homelessness, as well as mobilizing other prevention efforts, such as affordable housing policies and other measures that lift families out of poverty (Rog and Buckner, 2007).

Several authors (e.g., Fazel et al., 2008; Folsom and Jeste, 2002; Wright et al., 1998), in substantial reviews of multiple studies on homelessness and the mentally ill, note that the rate of mental disorders is higher among the homeless compared with the domiciled population. Estimates of mental disorders have varied from 20% to 90%.

In a 1996 national survey of clients of homeless service providers, 45% of respondents self-reported experiences with mental health problems in the previous year (Burt et al., 2001). Fazel and colleagues (2008) systematically reviewed surveys of the prevalence of mental and substance disorders among the homeless in Western countries (United States, United Kingdom, Germany, Australia, Netherlands, France, and Greece) that were conducted between 1979 and 2005. The pooled prevalence of psychotic disorders among homeless persons was 12.7%, with a range of 3% to 42%, which is a higher rate than found in housed populations.

Recent reports from the U.S. Conference of Mayors (2008a) and HUD (2008) indicate that 26% to 28% of the homeless population had a serious mental illness. Other studies conducted at local or regional levels also report that the prevalence of mental disorders is higher in homeless populations than comparative groups within the general population (Forney, Lombardo, and Toro, 2007; Goldstein et al., 2008; North, Eyrich, Pollio et al., 2004).

Estimates of the rates of the use of legal and illegal substances among homeless populations are higher than rates found in comparative groups. Wright et al. (1998) allege that the estimated rate of alcohol abuse exceeds 40% among the nations’ homeless and is near 50% among homeless men. Fazel et al. (2008) estimated that alcohol dependence ranged from 8.5% to 58.5% with a pooled estimate of 38%, and other types of substance dependence ranged from 4.7% to 54.2% with a pooled estimate of 24%. In the previously mentioned 1996 national survey (Burt, Aron, Douglas et al., 1999; Burt et al., 2001), 46% of the adult respondents reported problems with alcohol, and 38% reported problems with other substances within the previous year. HUD’s report indicated that 39% of sheltered adults were persons with chronic substance abuse problems (HUD, Office of Community Planning and Development, 2008).

Substance use carries considerable health risks. Alcohol abuse and dependence are associated with a wide range of health problems involving the liver, nervous system, and heart. The loss of economic productivity, vulnerability to accidents, and victimization are common outcomes. Substance use involving intravenous administration carries risks of infections (e.g., hepatitis); STDs (e.g., HIV); and significant social, legal, and economic problems (Forney et al., 2007; Kim, Daskalakis, Plumb et al., 2008; Wolitski, Kidder, and Fenton, 2007).

Moreover, for a sizable proportion of the homeless, severe mental illness exists concomitantly with the problems of alcohol or other types of substance use. Terms used to denote this phenomenon include co-occurrence disorders, comorbidity, and dual diagnosis (Forney et al., 2007; Mares, Greenberg, and Rosenheck, 2008; U.S. Department of Health and Human Services, Substance Abuse and Mental Health Services Administration, Center for Substance Abuse Treatment, 2007).

As noted by the reporting authors, there is considerable variation in prevalence rates for mental and substance use disorders. This variation is attributed to differences that include diagnostic criteria, sampling methods, participation rates, definitions of homelessness, and geographic locations. Much of the available information is based on data collected in the previous two decades. Current information regarding the prevalence of mental and substance use disorders among homeless people is only recently available. The Third Annual Homeless Assessment Report (AHAR) (HUD, Office of Community Planning and Development, 2008) was the first based on a full year of the HMIS data. HUD expects this report to provide a baseline for subsequent annual reports.

As noted in the previous section, many homeless individuals experience both mental and substance disorders. These are the individuals included in the federal definition of the chronically homeless. More specifically, these are unaccompanied adults who are homeless for extended or numerous periods and have one or more disabling conditions. The disabling conditions that chronically homeless people experience are very often severe mental and substance use disorders (Caton, Dominguez, Schanzer et al., 2005; Caton et al., 2007; Larimer, Malone, Garner et al., 2009; Sadowski, Kee, VanderWeele et al., 2009). This subpopulation is also at increased risk for the health problems outlined in previous sections on the health status of men and women.

As of January 2007, the chronically homeless represented 18% of the total sheltered and unsheltered homeless population. Two thirds of the chronically homeless were unsheltered, sleeping on the street or in places not meant for human habitation. Advocates that support focusing on this subpopulation of the homeless cite studies that indicate the chronically homeless, although comprising a relative smaller proportion of all homeless persons, use a disproportionate amount of homeless services. Others, although not discounting the problems of this group, indicate that the federal definition is too narrow. The policy excludes children, parents, youth, with or without disabilities, and adults whose housing status does not meet the required duration or frequency (Kertesz and Weiner, 2009; Larimer et al., 2009; Rosen, 2009; Sadowski et al., 2009).