Trauma and Posttraumatic Stress Disorder Among Homeless Young Adults: The Importance of Victimization Experiences in Childhood and Once Homeless

Abstract

Homelessness itself is traumatic, and more than half of homeless young adults have also experienced abuse as children and/or victimization while homeless. These experiences increase the likelihood of developing trauma-related symptoms and posttraumatic stress disorder (PTSD). Few studies have, however, examined correlates of trauma and PTSD to identify targets for prevention and intervention. We used multinomial logistic regression to assess whether child abuse, victimization once homeless, features of homelessness (duration and transience), and personal resilience (self-efficacy and social connectedness) were associated with trauma and PTSD among 600 homeless young adults. Compared with those who had not experienced trauma, those who had were more likely to have been physically and/or sexually abused in childhood and physically victimized once homeless. Compared with those who had not experienced trauma, those who had experienced trauma and met criteria for PTSD were more likely to have been physically and/or sexually abused in childhood and physically and/or sexually victimized once homeless, and to have lower self-efficacy and social connectedness. Attention should be paid to these correlates of trauma and PTSD in developing and refining trauma-informed prevention and intervention approaches.

Keywords

homeless young adults trauma PTSD childhood abuse victimization

In the United States, approximately 550,000 to 2 million young adults between the ages of 18 and 25 are homeless in any given year (National Alliance to End Homelessness, 2012; Whitbeck, 2009). Homeless young adults are defined as those 18 to 25 years of age who lack a fixed, regular, and adequate nighttime residence, which includes those living in emergency or transitional shelters, in motels, campgrounds, public spaces, abandoned buildings, or in other places not ordinarily used as regular sleeping accommodations (U.S. Department of Education, 2002). Homelessness in young adulthood is strongly related to experiences of abuse or neglect in childhood. Some homeless young adults initially ran away from home during childhood or adolescence to escape abusive or neglectful family situations, and others were placed in the foster care system due to family adversities (e.g., abuse, neglect, or parental incarceration) and became homeless upon aging out of the system (Moore, 2005). Life on the streets often results in additional risks and vulnerabilities, including food and housing insecurity, exploitation, trauma, and victimization (Coates & McKenzie-Mohr, 2010).

Emerging adulthood has come to be identified as a distinctive developmental period occurring from the late teens through the mid- to late-20s during which individuals explore their identity in the areas of love, work, and worldviews and options for their future (Arnett, 2000, 2004). This period is generally a psychologically challenging time for young adults, whether housed or homeless, because they often feel both anxiety and excitement about their future (Moore, 2005; Thompson, Ferguson, Bender, Begun, & Kim, 2015). For homeless young adults, these transitional challenges are often exacerbated due to multiple interrelated issues, including mental disorders, ongoing victimization experiences, unstable living conditions, and an absence of basic resources, which often prevent them from achieving these developmental tasks on time (Thompson et al., 2015; Whitbeck, 2009). Delays in achieving developmental tasks can result in an inability to become self-sufficient in adulthood (Arnett, 2000, 2004).

Victimization and other negative experiences are more prevalent among homeless than housed young adults (Cauce et al., 2000; Moore, 2005; Rew, 1996; Stewart et al., 2004; Whitbeck, Johnson, Hoyt, & Cauce, 2004) and can cause trauma or posttraumatic stress disorder (PTSD). As many as one third of homeless young adults (32.9%; aged 18–24) report having experienced trauma but do not meet criteria for PTSD, while 56.8% report both trauma and PTSD (Bender, Ferguson, Thompson, Komlo, & Pollio, 2010). The hallmarks of PTSD include intrusive symptoms and marked alterations in cognition and reactivity after exposure to one or more traumatic events (American Psychiatric Association [APA], 2013). Trauma and PTSD symptoms are also associated with a host of mental health correlates, including psychiatric comorbidity, suicidal ideation, and suicide attempts (e.g., Davidson, Hughes, Blazer, & George, 1991; Kessler, 2000; Kessler, Borges, & Walters, 1999), depression (e.g., Ryan, Kilmer, Cauce, Watanabe, & Hoyt, 2000), and substance use disorders (e.g., Bender, Thompson, Ferguson, & Langenderfer, 2014; Ferguson, 2009). Despite high prevalence rates and serious effects, only a few studies have examined the correlates of trauma and PTSD among homeless young adults (Cauce et al., 2000; Moore, 2005; Rew, 1996). To prevent trauma and trauma with PTSD, and to identify targets for intervention among homeless young adults, the present study explored potential correlates of trauma and PTSD in a sample of homeless young adults (aged 18–24) in three U.S. cities.

Correlates of Trauma and PTSD

Trauma and PTSD may result from childhood abuse and victimization experiences once homeless. In one of the few studies on the topic, experiencing multiple types of child abuse and victimization once homeless were both found to be associated with a greater likelihood of PTSD among homeless young adults (aged 18–24; Bender, Brown, Thompson, Ferguson, & Langenderfer, 2014). Another study also found that homeless young adults (aged 18–24) who experienced repeated victimization once homeless and a combination of direct and witnessed violence once homeless were more likely than those who had a single victimization experience or witnessed but did not directly experience victimization to have PTSD (Bender, Ferguson, Thompson, & Langenderfer, 2014). Others have found that family abuse and street victimization were associated with PTSD among homeless adolescents (aged 16–19; Whitbeck, Hoyt, Johnson, & Chen, 2007). Though few studies have investigated associations among child abuse, victimization once homeless, and trauma, prior work does suggest that experiences of child maltreatment, specifically physical and/or sexual abuse, as well as continued street victimization, place homeless young adults at greater risk for trauma as well as PTSD (Bender, Brown, et al., 2014; Bender, Ferguson, et al., 2014; Tyler, Hoyt, Whitbeck, & Cauce, 2001; Whitbeck et al., 2007).

Other factors once homeless may also increase younger individuals’ risk for trauma and PTSD. Homeless adolescents (aged 13–19; Baer, Peterson, & Wells, 2004) and young adults (aged 18–24; Bender et al., 2010) are often transient, remaining in the same location for only short periods of time. Although transience can be an adaptive coping strategy leading to increased availability of services and support (Wolch, Rahimian, & Koegel, 1993), it can also lead to loss of important relationships and supports and place homeless individuals in unpredictable and often unsafe situations (Ferguson, Bender, & Thompson, 2013; Layton, 2000). Research with homeless young adults (aged 18–24) finds that each additional move they made to another city was associated with increased odds of meeting criteria for PTSD, yet not for experiencing trauma (Bender et al., 2010). This finding suggests transience may exacerbate the risk for PTSD but not trauma.

Duration of homelessness is another risk factor. The longer young adults (aged 18–24) remain homeless, the more likely they are to experience adverse situations (Ferguson, Kim, & McCoy, 2011) and to use alcohol and drugs (Thompson, Bender, Ferguson, & Kim, 2015). In another study, length of time homeless was also associated with fewer positive coping behaviors among homeless adults aged 18 to 65 (Stein, Dixon, & Nyamathi, 2008). Thus, homelessness duration may be linked to trauma symptoms and PTSD among homeless young adults given its association with negative experiences, risky behaviors, and poorer coping skills.

Homeless young adults may also have assets or strengths that can mitigate the likelihood of poor outcomes (Fraser, Galinsky, & Richman, 1999). For example, self-efficacy, the belief in one’s abilities to succeed when faced with a particular challenge (Bandura, 1993), may enhance coping or resilience through cognitive, motivational, and affective processes in the face of difficulties (Benight & Bandura, 2004). One study found that homeless young adults (aged 18–24) with a greater sense of self-efficacy were less likely to meet criteria for PTSD, but self-efficacy did not decrease the likelihood of having experienced trauma (Bender et al., 2010). Saigh, Mroueh, Zimmerman, and Fairbank (1995) studied three groups of housed adolescents (aged 13): those with trauma and PTSD, those with trauma without PTSD; and those without trauma. The latter two groups did not differ in self-efficacy, but those with trauma and PTSD had significantly lower self-efficacy than the other groups (Saigh et al., 1995). Such studies indicate that self-efficacy might not fully protect homeless young adults from trauma but may help prevent those who have experienced trauma from developing PTSD. These ideas are consistent with findings from a sample of housed children, adolescents, and adults indicating that higher self-efficacy may help young adults feel a greater sense of control amid their adverse circumstances and thus decrease their likelihood of developing PTSD (e.g., Davis & Siegel, 2000; Heinrichs et al., 2005; Kennedy et al., 2007).

Social connectedness, defined as the subjective awareness of interpersonal closeness with the social world based on the aggregate experiences of proximal and distal relationships (Lee & Robbins, 1995), may buffer young adults from trauma and PTSD. Cohen, Gottlieb, and Underwood (2000) suggested that social connectedness decreases a sense of isolation and increases feelings of control and self-esteem. Although research specific to homeless young adults on this topic is limited, previous studies of housed young adults (aged 17–22) found that social connectedness is associated with decreased risks of trauma and PTSD (Haden et al., 2007). Another study also found that connectedness with friends, families, or significant others was associated with a lower likelihood of PTSD in a sample of housed female young adults (average age = 25.21; Besser, Weinberg, Zeigler-Hill, & Neria, 2014).

Social connectedness can decrease young adults’ risky behaviors and improve their recovery from trauma (Nooner et al., 2012). For homeless young adults, however, social connectedness may function differently. Rather than connections with traditional peers and others, homeless young adults’ connectedness may be with those who are experiencing adverse events (e.g., drug abuse). While one qualitative study found that street peers provided safety, subsistence, and emotional stability for homeless young adults (Bender, Thompson, McManus, Lantry, & Flynn, 2007), other quantitative studies found that homeless youth (aged 14–24) exposed their peers to risky behaviors and circumstances, such as substance use and sexual risk behaviors (Bousman et al., 2005; Ennett, Bailey, & Federman, 1999). Thus, social connectedness deserves further exploration, as it may be a risk-enhancing or risk-decreasing factor.

Based on previous research, the current study aimed to identify factors associated with the experience of trauma and the development of PTSD symptomology among homeless young adults in three cities in disparate regions of the United States. Correlates, including childhood abuse (physical and sexual abuse), victimization once homeless (physical and sexual), homeless lifestyle factors (transience and length of homelessness), and personal resilience factors (self-efficacy and social connectedness) were examined for their potential ability to differentiate among three groups of homeless young adults: (a) those who do not report experiencing trauma, (b) those who report experiencing trauma but not PTSD, and (c) those who report experiencing trauma and PTSD.

The following hypotheses guided this study: experiences of (a) childhood physical and (b) sexual abuse will be associated with an increased likelihood of experiencing trauma (H1a and H1b, respectively) and PTSD (H2a and H2b, respectively); experiences of (c) physical and (d) sexual victimization once homeless will be associated with an increased likelihood of experiencing trauma (H1c and H1d, respectively) and PTSD (H2c and H2d, respectively); (e) length of homelessness will be associated with an increased likelihood of experiencing trauma (H1e) and PTSD (H2e); (f) transience and (g) self-efficacy will not be associated with an increased likelihood of experiencing trauma (H1f and H1g, respectively) but more transience and lower self-efficacy will be associated with an increased likelihood of PTSD (H2f and H2g, respectively); (h) social connectedness will be associated with a decreased likelihood of experiencing trauma (H1h) and PTSD (H2h).

Method

Research Design and Settings

This cross-sectional study of homeless young adults was conducted in three U.S. cities. One agency per city was selected based on its existing relationship with the researchers and commitment to participate. These agencies were multiservice, nonprofit organizations that offer homeless, runaway, and at-risk adolescents and young adults comprehensive services, including street outreach, meals, shelter, health care, counseling, and educational and employment services. The study received human subjects’ approval from the three primary investigators’ university-based institutional review boards.

Participants and Recruitment Procedures

Using purposive sampling, researchers recruited 601 service-seeking homeless young adults (aged 18–24) in Los Angeles (n = 200), Austin (n = 200), and Denver (n = 201). The researchers specifically sought participants from three different types of programs at each of the three host agencies: (a) street outreach/drop-in centers (nonresidential; 62% of sample); (b) residential short-term and midlength shelters (30 days to up to 6 years; 34% of sample); and (3) transitional (long-term) housing (4% of sample). Recruitment took place from March 2010 through July 2011 during the agencies’ service hours. Young adults were eligible to participate if they were 18 to 24 years of age, were seeking services at one of the host agencies, and had been homeless for at least 2 weeks of the month prior to their interview as Whitbeck (2009) operationalized in his research. Agency staff determined whether clients met eligibility criteria and referred eligible participants to the research interviewers, who then explained interview procedures and secured written informed consent. Of young adults invited to participate, 95% to 98% agreed to be interviewed across the three data collection agencies.

Data Collection and Measures

Researchers administered a 45-min, structured interview to each young adult. Due to the personal nature of the questions, all interviews were conducted in private rooms at the participating agencies. For more sensitive topics (e.g., experiences of child abuse), interviewees had the option of reading and filling in the questionnaire by themselves or being interviewed aloud. Interviewees received a US$10 gift card to a local food vendor for their participation.

Dependent variable

The dependent variable, trauma/PTSD status, was divided into three categories (0 = young adults who had not experienced trauma and by definition did not qualify for a diagnosis of PTSD, 1 = young adults who had experienced trauma but did not meet PTSD criteria, and 2 = young adults who had experienced trauma and met PTSD criteria). The variable was measured using the PTSD module of the Mini-International Neuropsychiatric Interview (MINI; Sheehan et al., 1998), which is based on the Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; APA, 1994), and has previously demonstrated good reliability (Cohen’s kappa coefficient = .78; Sheehan et al., 1998). This scale has been used in similar studies with both the general population and homeless young adults (Behrendt & Moritz, 2014; Bryant et al., 2014; Thompson, Jun, Bender, Ferguson, & Pollio, 2010).

The PTSD module of the MINI contains sequential screening questions regarding (a) whether or not participants had ever experienced or witnessed an extremely traumatic event that included actual or threatened death or serious injury to them or someone else; if yes, (b) whether they responded with intense fear, helplessness, or horror; and if yes, (c) whether, during the past month, they re-experienced the event in a distressing way (dreams, intense recollections flashbacks, or physical reactions). If respondents answered “yes” to all three screening questions, the module included 13 additional questions reflecting Diagnostic and Statistical Manual of Mental Disorders (4th ed., text revision [DSM-IV-TR]; APA, 2000) symptoms of re-experiencing, avoidance, and arousal symptoms during the past month. Participants who responded negatively to the first screening question were categorized as not having experienced trauma (No Trauma). Those who experienced trauma and responded affirmatively to both the second and third screening questions and five or more avoidance/arousal symptoms in the past month were categorized as meeting criteria for trauma and PTSD (Trauma With PTSD). All others were classified as having experienced trauma but not PTSD (Trauma Without PTSD).

Independent variables

Childhood abuse

Childhood abuse was retrospectively assessed using the Childhood Trauma Questionnaire (CTQ; Bernstein & Fink, 1998), which has previously demonstrated good to high reliability (Cronbach’s α = .79–.86; Bernstein & Fink, 1998). The current study included two abuse variables, each based on a separate five-item CTQ subscale, one measuring physical abuse and one measuring sexual abuse experienced before becoming homeless. Physical abuse consisted of items such as “people in my family hit me so hard it left me with bruises or marks” and sexual abuse consisted of items such as “someone molested me.” Both subscales showed high reliability in the current study (Cronbach’s α for physical abuse = .88 and sexual abuse = .97). Participants who endorsed any of the five items for each variable were coded as having experienced physical and/or sexual abuse, respectively (0 = never experienced, 1 = experienced).

Victimization once homeless

Victimization once homeless was measured using the Traumatic Life Events Questionnaire (TLEQ; Kubany et al., 2000). In this study, victimization once homeless consisted of two variables: (a) physical victimization and (b) sexual victimization. The physical victimization (both direct and indirect forms) variable was created by combining three items that assessed whether the young adults had experienced (a) physical assault by acquaintance or stranger, (b) threat of death or serious bodily harm, and (c) physical assault by an intimate partner. In this study, Cronbach’s α was moderate at .63. Participants who had one or more of these three experiences were coded as having been physically victimized (0 = never experienced, 1 = experienced). Sexual victimization was created by combining two items that assessed whether young adults had experienced (a) sexual assault by acquaintance or stranger or (c) sexual assault by an intimate partner. In this study, Cronbach’s α was moderate at .61. Participants who had experienced one or both types of sexual victimization once homeless were coded as having been sexually victimized (0 = never experienced, 1 = experienced).

Homeless lifestyle factors

Length of time homeless was coded as the number of months between the interview date and the date the young adult became homeless. Transience was measured as the total number of times the participant had moved to another (new or repeated) city since becoming homeless.

Personal resilience factors

Self-efficacy was measured using the self-efficacy module of the Client Evaluation of Self and Treatment measure (CEST; Joe, Broome, Rowan-Szal, & Simpson, 2002) comprised of seven Likert-type scale items (e.g., “what happens to you in the future mostly depends on you”) with 1 = strongly disagree to 5 = strongly agree. After reverse coding relevant items, all items were summed so that higher scores represent a greater sense of self-efficacy (range = 7–35). This variable had moderate reliability in this study (Cronbach’s α = .62).

Social connectedness was measured using the Social Connectedness Scale to assess a person’s sense of affiliation, frustration, and difficulty in connecting with friends, people, and society around himself or herself (Lee & Robbins, 1995). The subscale contains eight Likert-type scaled items (e.g., “I don’t feel related to anyone”; “I feel disconnected from the world around me and even around people I know”; “I don’t feel that I really belong”) with 1 = strongly agree to 6 = strongly disagree. After reversing coding relevant items, the eight items were summed with higher scores indicating greater social connectedness (range = 8–48). This variable had strong reliability in this study (Cronbach’s α = .90).

Control variables

Control variables were participant’s gender (0 = male and 1 = female), age, and data collection location site (dummy coded for inclusion in multivariate analyses).

Data Analysis

IBM SPSS Statistics 20 was used for all analyses. Missing data analysis showed that the proportion of missing cases for the independent and dependent variables was less than 2%, with 592 (98.5%) out of 601 cases having no missing data. In addition, Little’s Missing Cases at Random test suggested that the missing data were completely at random (p ≥ .05). However, the outlier test identified one case with more than a +4.0 standard score; this case was deleted (Hair et al., 2010). Thus, the final sample included 600 cases, and the mean substitution method was applied to other missing values (Hair, Black, Babin, & Anderson, 2010).

Bivariate analyses were performed using ANOVA and chi-square tests to examine the relationships between the independent variables (childhood abuse, victimization once homeless, homeless lifestyle factors, personal resilience factors) as well as the demographic factors and the three-category dependent variable (no trauma, trauma without PTSD, and trauma with PTSD). Tolerance values were under 1.0 and variance inflation factors were between 1.0 and 1.4 indicating that multicollinearity was not a problem (Hair et al., 2010). A multinomial logistic regression model was analyzed by regressing the three-category dependent variable on the independent variables controlling for gender, age, and data collection location. The reference group for the dependent variable was the no-trauma group; thus, all multinomial logistic regression results report the likelihood of being in the trauma without PTSD group or the trauma with PTSD group compared with the no-trauma group. In addition, a classification and regression tree (CART) model was used to differentiate those with trauma and PTSD from those who had trauma without PTSD with the two-category dependent variable trauma without PTSD/trauma with PTSD and the same independent variables. Finally, we investigated the effects of abuse and victimization further by conducting post hoc multinomial regressions to determine whether accumulated, that is, multiple forms of, abuse and victimization were associated with experiencing trauma only and with trauma combined with PTSD compared with no trauma.

Results

Univariate analysis of the sample of 600 homeless young adults (see Table 1) revealed that they spent an average of 32 (SD = 30.88) months homeless, and on average had 3.5 (SD = 3.69) inter-city moves. During childhood, 80.0% reported experiencing physical abuse and 33.7% sexual abuse. Once homeless, 68.5% reported experiencing physical victimization and 22.8% sexual victimization. Of the sample, 27.2% reported no trauma experiences; 50.5% experienced trauma but did not meet PTSD criteria; and 22.3% experienced trauma and PTSD.

Table 1.

Descriptive Statistics of Homeless Young Adults for Total Sample and by Trauma and PTSD Groups.

	Total sample (N = 600)	No trauma (n = 163)	Trauma without PTSD (n = 303)	Trauma with PTSD (n = 134)	F(χ²)
Variables	M ± SD/n (%)	M ± SD/n (%)	M ± SD/n (%)	M ± SD/n (%)	F(χ²)
Age	20.05 ± 1.61	19.83 ± 1.55	20.21 ± 1.66	19.96 ± 1.53	3.38*
Gender					(9.10*)
Male	384 (64.0)	109 (66.9)	204 (67.3)	71 (53.0)
Female	216 (36.0)	54 (33.1)	99 (32.7)	63 (47.0)
City					(20.35***)
Austin	200 (33.3)	50 (30.7)	118 (38.9)	32 (23.9)
Denver	201 (33.5)	62 (38.0)	101 (33.3)	38 (28.4)
Los Angeles	199 (33.2)	51 (31.3)	84 (27.7)	64 (47.8)
Childhood physical abuse	480 (80.0)	108 (66.3)	251 (82.8)	121 (90.3)	(29.65***)
Childhood sexual abuse	202 (33.7)	30 (18.4)	96 (31.7)	76 (56.7)	(49.41***)
Physical victimization once homeless	411 (68.5)	81 (49.7)	221 (72.9)	109 (81.3)	(39.73***)
Sexual victimization once homeless	137 (22.8)	24 (14.7)	54 (17.8)	59 (44.0)	(44.57***)
Self-efficacy	26.28 ± 4.23	26.82 ± 4.06	26.86 ± 4.21	24.31 ± 3.91	19.86***
Social connectedness	33.24 ± 9.35	34.81 ± 8.66	34.28 ± 9.39	28.96 ± 8.84	19.28***
Length of time homeless (months)	32.36 ± 30.88	26.29 ± 28.06	34.94 ± 30.83	33.88 ± 33.39	4.42*
Transience (times)	3.50 ± 3.69	2.59 ± 3.27	4.04 ± 3.94	3.35 ± 3.35	8.51***

Note. PTSD = posttraumatic stress disorder. No trauma indicates young adults who have not experienced trauma; trauma without PTSD indicates young adults who have experienced trauma but do not meet criteria for PTSD; Trauma with PTSD indicates young adults who have experienced trauma and meet criteria for PTSD.

p < .05. **p < .01. ***p < .001.

Bivariate analyses (see Table 1) also showed that compared with those without trauma, percentages of childhood abuse and victimization once homeless were higher among those with trauma but not PTSD. Compared with those without trauma, those with trauma and PTSD also exhibited higher percentages of childhood abuse and victimization once homeless and lower levels of self-efficacy and social connectedness.

The multinomial logistic regression model (see Table 2) indicated that the factors in the model accurately predicted the three-category dependent variable. The model’s classification accuracy rate (57.2%) was higher than the proportional by chance accuracy rate (37.9%). The overall fit was statistically significant, Nagelkerke R² = .295, χ²(df = 24) = 178.76, p < .001.

Table 2.

Multinomial Logistic Regression Model of Those With Trauma Without PTSD and Those With Trauma and PTSD Compared With Those Without Trauma.

	Trauma without PTSD		Trauma with PTSD
Variables	B (SE)	OR (95% CI)	B (SE)	OR (95% CI)
Childhood abuse
Physical abuse	0.56* (0.24)	1.75 [1.09, 2.82]	1.17** (0.39)	3.23 [1.51, 6.93]
Sexual abuse	0.66* (0.27)	1.94 [1.14, 3.28]	1.13*** (0.32)	3.10 [1.66, 5.78]
Victimization once homeless
Physical victimization	0.84*** (0.23)	2.32 [1.49, 3.62]	1.28*** (0.32)	3.60 [1.93, 6.70]
Sexual victimization	−0.31 (0.30)	0.74 [0.41, 1.34]	0.59^† (0.34)	1.80 [0.93, 3.49]
Personal resilience factors
Self-efficacy	0.02 (0.03)	1.02 [0.97, 1.08]	−0.07* (0.04)	0.93 [0.87, 0.99]
Social connectedness	−0.00 (0.01)	1.00 [0.97, 1.02]	−0.04* (0.02)	0.96 [0.93, 0.99]
Homeless life factors
Length of months homeless	0.00 (0.00)	1.00 [0.99, 1.01]	−0.00 (0.01)	1.00 [0.99, 1.01]
Transience	0.08* (0.04)	1.09 [0.95, 1.17]	0.01 (0.05)	1.07 [0.88, 1.31]
Demographic factors
Age	0.10 (0.08)	1.10 [0.95, 1.28]	0.07 (0.10)	1.07 [0.88, 1.31]
Female	−0.01 (0.24)	0.99 [0.627, 1.57]	0.13 (0.30)	1.14 [0.63, 2.06]
City (Austin)	0.32 (0.30)	1.38 [0.77, 2.46]	1.53*** (0.39)	4.59 [2.14, 9.86]
City (Denver)	0.32 (0.26)	1.38 [0.82, 2.32]	1.20*** (0.33)	3.31 [1.73, 6.33]
Nagelkerke pseudo R² = .295, Model χ²(24) = 178.76, p < .001

Note. Reference group for the dependent variable is young adults who have not experienced trauma. Reference groups for childhood abuse and victimization once homeless are homeless young adults who never experienced abuse or victimization, respectively. Reference group for location of data collection is Los Angeles. CI = confidence interval; OR = odds ratio; PTSD = posttraumatic stress disorder.

†

p < .10. *p < .05. **p < .01. ***p < .001.

Four factors were significantly associated with an increased likelihood of being in the trauma without PTSD group compared with the no-trauma group. Having experienced childhood physical and/or sexual abuse was associated with a greater likelihood of experiencing trauma without PTSD than no trauma (physical abuse: odds ratio [OR] = 1.75, 95% confidence interval [CI] = [1.09, 2.82]; sexual abuse: OR = 1.94, 95% CI = [1.14, 3.28]). Youth who had been physically victimized while homeless were more likely to experience trauma without PTSD than no trauma (OR = 2.32, 95% CI = [1.49, 3.62]). Transience was also significant; each additional move homeless young adults made to another city increased the odds of experiencing trauma without PTSD compared with experiencing no trauma (OR = 1.09, 95% CI = [0.95, 1.17]).

Seven factors were significantly associated with an increased likelihood of being in the trauma with PTSD group compared with the no-trauma group. Young adults who experienced childhood physical (OR = 3.23, 95% CI = [1.51, 6.93]) and sexual (OR = 3.10, 95% CI = [1.66, 5.78]) abuse and who had been physically (OR = 3.60, 95% CI = [1.93, 6.70]) and sexually (OR = 1.80, 95% CI = [0.93, 3.49]) victimized while homeless were 2 to 3 times more likely to experience trauma and PTSD than no trauma. Those who reported higher levels of self-efficacy and social connectedness were significantly less likely to be in the trauma with PTSD group than the no-trauma group (OR = 0.93, 95% CI = [0.88, 0.99] and OR = 0.96, 95% CI = [0.93, 0.98], respectively). Last, young adults in Austin and Denver were more likely than those in Los Angeles to be in the trauma and PTSD group than in the no-trauma group.

The CART model (see Figure 1) indicated that the model’s classification accuracy rate (73.0%) was high. Results show that three variables differentiated those who experienced trauma without PTSD from those with trauma and PTSD: self-efficacy, childhood sexual abuse, and sexual victimization once homeless. In the group that had low levels of self-efficacy (≤23.0), 53.7% had PTSD compared with 21.8% of the group that had high levels of self-efficacy (>23.0). Among the group that had low self-efficacy, 62.5% of those who had experienced sexual abuse in childhood had PTSD compared with 43.9% of those who had not experienced sexual abuse in childhood.

Figure 1.

Findings of the classification and regression tree model: Distinguishing the trauma with PTSD group from the trauma without PTSD group.

In addition to examining the association of each type of abuse or victimization with trauma and PTSD, Table 3 shows the results of the post hoc analyses conducted to determine whether accumulated abuse and victimization differentiated the no-trauma group from the trauma but no PTSD group and the trauma and PTSD group. Homeless young adults who experienced all four types of abuse and victimization included in this study (childhood physical abuse, childhood sexual abuse, physical victimization once homeless, and sexual victimization once homeless) were 11 times more likely to experience trauma without PTSD compared with those who had not experienced any of these types of abuse and victimization. Homeless young adults who experienced two or three types of abuse and victimization were 3 to 4 times more likely to experience trauma without PTSD compared with those who never experienced any of these four types of abuse or victimization. While experiencing one type of abuse did not differentiate those who did not experience trauma from those who had trauma and PTSD, experiencing two, three, or four types of abuse progressively increased the likelihood of experiencing trauma and PTSD 4.8, 14.2, and 67.9 times, respectively.

Table 3.

Multinomial Logistic Regression Model for Those With Trauma Without PTSD and Those With Trauma and PTSD Compared to Those Without Trauma: Focusing on Accumulation of Abuse and Victimization.

	Trauma without PTSD		Trauma with PTSD
Variables	B (SE)	OR (95% CI)	B (SE)	OR (95% CI)
Accumulation of abuse in childhood and victimization once homeless
Four types	2.40*** (0.63)	10.97 [3.19, 37.68]	4.22*** (0.79)	67.86 [14.17, 319.47]
Three types	1.51*** (0.42)	4.51 [1.99, 10.24]	2.65*** (0.64)	14.17 [4.05, 49.63]
Two types	1.09** (0.34)	2.97 [1.52, 5.80]	1.57** (0.59)	4.79 [1.50, 15.34]
One type	0.65^† (0.36)	1.92 [0.96, 3.86]	0.55 (0.65)	1.73 [0.48, 6.16]
Personal resilience factors
Self-efficacy	0.01 (0.03)	1.02 [0.97, 1.08]	−0.08* (0.04)	0.93 [0.87, 0.99]
Social connectedness	−0.00 (0.01)	1.00 [0.97, 1.03]	−0.04* (0.02)	0.96 [0.93, 0.99]
Homeless life factors
Length of months homeless	0.00 (0.00)	1.00 [0.99, 1.01]	−0.00 (0.01)	1.00 [0.99, 1.01]
Transience	0.08* (0.04)	1.09 [1.01, 1.17]	−0.05 (0.05)	1.05 [0.96, 1.15]
Demographic factors
Age	0.10 (0.08)	1.11 [0.96, 1.28]	0.07 (0.10)	1.07 [0.88, 1.30]
Female	−0.14 (0.23)	0.87 [0.56, 1.36]	0.01 (0.29)	1.01 [0.58, 1.79]
City (Austin)	0.28 (0.29)	1.32 [0.75, 2.33]	1.47*** (0.39)	4.33 [2.04, 9.21]
City (Denver)	0.24 (0.26)	1.27 [0.76, 2.10]	1.13** (0.33)	3.10 [1.63, 5.90]
Nagelkerke Pseudo R² = .286, Model χ²(24) = 172.42, p < .001

Note. Reference group for the dependent variable is young adults who have not experienced trauma. Reference group for accumulation of child abuse and victimization once homeless is homeless young adults who never experienced abuse or victimization. Reference group for location of data collection is Los Angeles. CI = confidence interval; OR = odds ratio; PTSD = posttraumatic stress disorder.

†

p < .10. *p < .05. **p < .01. ***p < .001.

Discussion

This study sought to identify correlates of trauma and PTSD among a multicity sample of homeless young adults. Nearly half of the 600 homeless young adults in the sample had experienced trauma, slightly less than the 56.8% identified in an earlier study (aged 18–24; Bender et al., 2010). Approximately one fifth of the sample experienced PTSD, similar to some other studies that have identified rates of 10% to 18% among homeless adolescents and young adults (Bender et al., 2010; Cauce et al., 2000; Whitbeck et al., 2004). These rates of PTSD are substantially higher than for the general population of young adults (3%–4%; Bernat, Ronfeldt, Calhoun, & Arias, 1998; Cuffe et al., 1998).

Of the potential correlates of trauma and PTSD examined, homeless young adults who had experienced physical and/or sexual abuse as children were more likely to be in the group that experienced trauma with and without PTSD than in the no-trauma group. Moreover, experiencing sexual abuse in childhood differentiated the trauma with PTSD group from the trauma without PTSD group. Previous studies have also found associations between child abuse and mental disorders (Ferguson, 2009; Tyler & Melander, in press). Abusive family environments may contribute to homelessness at an earlier age, increasing the length of time homeless and number of exposures to traumatic events, thereby resulting in a higher incidence of PTSD (Tyler et al., 2001). In the current study, the child abuse variables were associated with trauma and PTSD even when controlling for more recent victimization after being homeless, suggesting that prior childhood experiences continue to adversely affect young adults’ functioning while homeless.

Victimization while homeless was also detrimental for young adults. Homeless young adults who were physically victimized while homeless were more likely to have experienced trauma without PTSD than no trauma. Experiencing either physical or sexual victimization once homeless was related to young adults’ risk for meeting PTSD criteria. Moreover, experiencing sexual victimization once homeless was a factor that differentiated the trauma with PTSD group from the trauma without PTSD group. These results align with prior research showing that physical and sexual victimization once homeless is associated with experiencing mental disorders (Wenzel, Hambarsoomian, D’Amico, Ellison, & Tucker, 2006; Whitbeck, Hoyt, & Bao, 2000). In addition, the current study suggests that accumulated experiences of child abuse and victimization may result in trauma with and without PTSD among homeless young adults. Bender, Brown, et al. (2014) found that homeless young adults who experienced multiple types of abuse in childhood and victimization once homeless had a higher likelihood of PTSD compared with those who experienced fewer types of abuse in childhood and victimization. Because Bender, Brown, et al. (2014) explored factors associated with PTSD but not factors associated with trauma, we conducted post hoc analyses to examine the association between experiences of multiple types of child abuse and victimization once homeless and trauma and also found that the accumulation of childhood physical and sexual abuse and physical and sexual victimization while homeless resulted in a greater likelihood of trauma with and without PTSD. Future research should attempt to identify mechanisms by which accumulated adverse childhood experiences and victimization while homeless lead to trauma and PTSD.

Consistent with previous literature on homeless adolescents (aged 13; Saigh et al., 1995) and young adults (aged 18–24; Bender et al., 2010), this study showed that self-efficacy was not associated with a lower likelihood of experiencing trauma. Like other studies on children, adolescents, and adults (Davis & Siegel, 2000; Heinrichs et al., 2005; Kennedy et al., 2007), it also showed that self-efficacy was associated with a lower likelihood of having PTSD. Though correlational and not causative, our findings indicate that belief in one’s ability to control life does not necessarily offer protection from traumatic (negative or harmful) events but it may aid in effectively dealing with those negative experiences through cognitive, motivational, and affective processes and, ultimately, in preventing PTSD from developing.

Similarly, in this study, social connectedness was not to be related to avoiding trauma but it was related to avoiding PTSD. This finding supports previous research that social connectedness improves recovery from traumatic events among female young adults (Besser et al., 2014; Haden et al., 2007; Nooner et al., 2012). However, research on social connectedness among homeless young adults has produced inconsistent findings with regard to its association with homeless young adults’ mental health (Bender et al., 2007; Bousman et al., 2005; Ennett et al., 1999; Kidd & Shahar, 2008). Social connections, when comprised primarily of homeless peers, typically include influences that are both risk-enhancing (drug use, sexual risk behaviors; Bousman et al., 2005) and risk-decreasing (emotional support, protection on the street; Bender et al., 2007). In a previous study of homeless youth (aged 12–20), having prosocial peers was associated with fewer risk behaviors, and having antisocial peers were associated with more risk behaviors (Rice, Stein, & Milburn, 2008). These results suggest that the influence of social connectedness may vary across the types of social connections experienced and is an important factor for further study. In all, given research suggesting that self-efficacy and prosocial connectedness may mitigate PTSD or aid in its avoidance even among those who experienced multiple types of child abuse and victimization once homeless, interventions to increase self-efficacy and social connectedness among homeless young adults should be developed and tested.

Limitations

Study limitations should be considered in interpreting these findings. First, due to its cross-sectional design, causality could not be established. For example, it was not possible to discern whether PTSD symptoms followed victimization on the streets or whether they were already present due to previous (e.g., childhood) victimization. Future studies should examine longitudinal relationships among these potentially causal predictors of PTSD. Second, due to purposive sampling in three urban areas, findings may not be generalizable to all homeless young adults in the data collection cities or to those in other cities or nonurban areas. Third, because the sample was recruited from agencies providing services to homeless young adults, it is unclear whether similar findings would result from more hidden populations of homeless young adults who do not use services (Bender et al., 2010). Fourth, self-report interviews might be subject to recall bias if events happened some time ago and/or to social desirability bias, as young adults might hesitate to share sensitive information such as abuse, victimization, and mental health problems, leading to an underestimation of their challenges. Another measurement limitation is the imprecise measure of time homeless (number of months since leaving home), which might be inflated by including months that participants were not literally homeless. Finally, the DSM-IV diagnosis of PTSD may not capture complex symptoms of PTSD in homeless young adults (Stewart et al., 2004), and some symptoms of PTSD (i.e., difficulty sleeping, and being nervous or being constantly on your guard) may be characteristics of street survival behaviors rather than of PTSD (McManus & Thompson, 2008).

Implications

Despite these limitations, this study has implications for research and services for homeless young adults. First, direct service providers need education about PTSD. Although approximately one of every five homeless young adults may meet PTSD criteria, their mental health treatment utilization has been very low (De Rosa et al., 1999). Shelters and drop-in centers, which many homeless young adults use, are gateways to interventions for this population (De Rosa et al., 1999). Practitioners who are knowledgeable about trauma/PTSD and can screen for these problems can help mitigate symptoms and reduce risk for additional harm (Thompson, McManus, & Voss, 2006).

Second, clinicians should assess for history of childhood physical and/or sexual abuse in homeless young adults and treat associated outcomes. Although basic environmental safety and subsistence are prerequisites to addressing psychological issues (Newman, 2000), service providers should not disregard a history of abusive family environments. In addition, exploring past experiences of physical and/or sexual abuse and physical and/or sexual assault once homeless would be helpful in identifying young adults who are especially vulnerable to future victimization and need safety training to protect themselves from future harm. Prevention services are also needed because findings showed that among those with trauma, those who also had PTSD were more likely to have been sexually abused in childhood and sexually victimized once homeless and had lower levels of self-efficacy. Recent empirical evidence suggests homeless young adults can be trained to better detect risks on the streets (Bender et al., 2016), and such skills may be effective in helping them avoid victimization and related symptomatology. In particular, homeless young adults need safe places to sleep and live. Policymakers and service providers must increase the number of temporary shelters’ beds and transitional housing for this population. Housing young adults in shelters and transitional housing can also increase accessibility to mental health assessment and intervention (Greene, Ringwalt, & Iachan, 1997).

Finally, practitioners should focus on building self-efficacy and prosocial connectedness among homeless young adults as a means of preventing or mitigating PTSD. For example, Multi-Modality Trauma Treatment (MMTT), an intervention in improving self-efficacy to reduce PTSD symptoms for housed adolescents, could be tested with homeless young adults. Using Cognitive Behavioral Therapy protocols, MMTT has been reported as a durable short-term (i.e., 18 weeks) treatment with 57% of 17 treatment participants no longer meeting PTSD criteria immediately after treatment, and 86% free of PTSD 6 months after treatment (March, Amaya-Jackson, Murray, & Schulte, 1998). Because MMTT can be implemented in fewer sessions than the 18 weekly sessions recommended in the protocol (March et al., 1998), it may be appropriate for homeless young adults with high levels of transience. Research should test the effectiveness of specific treatments for PTSD such as MMTT that might help homeless young adults.

Footnotes

Acknowledgements

The authors thank Dr. Sanna J. Thompson on her data collection efforts in Austin.

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

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