Rates of cognitive and functional impairments in sheltered adults experiencing homelessness

Abstract

Objective:

The current study examined rates of objective cognitive and functional impairment, and associations between cognitive performance and performance-based functional capacity, in a well-characterized sample of 100 adults experiencing homelessness.

Method:

Participants completed a brief neuropsychological and functional capacity assessment, and self-report questionnaires. Cognitive impairment rates were determined by comparing mean scores to published normative data, as well as examining frequency of scores <1 SD below the mean. Pearson correlations examined associations between cognitive and functional capacity.

Results:

65% performed in the cognitively impaired range on a brief cognitive screening test, 30% had impaired processing speed, and 11% met cognitive criteria for intellectual disability. Furthermore, 48% of the sample met functional impairment criteria, and poorer cognitive performance was strongly associated with poorer performance-based functional capacity (ps<0.003).

Conclusion:

Cognitive and functional impairments are common within sheltered adults experiencing homelessness, underscoring the need for routine objective cognitive screening and rehabilitation services.

Homelessness is a major social and financial problem in the United States. Although substantial research explores medical, psychiatric, and socioeconomic pathways into homelessness, few studies have examined the relationship between cognitive impairment and homelessness (1,2). Furthermore, methodological inconsistencies have contributed to reports of variable rates of impairment; nevertheless, a consensus has emerged that cognitive impairment is over-represented in the homeless population and is likely to be both a risk factor for and perpetuator of homelessness (2).

Severe mental illnesses and substance use disorders (SMI/SUD) are highly prevalent in the homeless population and may adversely affect cognitive functioning along with additional risk factors, including traumatic brain injury, poverty, and malnutrition. Cognitive impairments are key determinants of functional outcomes in people with SMI/SUD (3,4), and it is likely that there are similar associations between cognitive deficits and psychosocial functioning in individuals who are homeless. Thus far, however, only one study has examined the relationship between objective cognitive and functional performance in a small sample of homeless (n=30) and housed (n=21) psychiatric inpatients with schizophrenia spectrum disorders (5). Although no significant differences were found between the two groups on cognitive and functional performance, poorer verbal memory and executive functioning/processing speed were independently predictive of poorer functional capacity in the full sample, underscoring the importance of neuropsychological screening and interventions to improve cognition and functional disability.

Stergiopoulos and colleagues’ findings bear great significance for the development and delivery of effective preventive and rehabilitative services for those at risk for and currently experiencing homelessness. Cognitive interventions in homeless populations, for example, may improve independence and daily functioning. Moreover, underappreciation of the presence and importance of cognitive and functional impairments within this community can adversely impact homeless individuals’ ability to utilize services and impede efforts to achieve housing and financial stability. As such, we aimed to examine: 1) rates of cognitive impairment and impaired functional capacity, and 2) the association between cognitive performance and performance-based functional capacity in sheltered adults experiencing homelessness. We hypothesized that rates of cognitive impairment and impaired functional capacity in adults experiencing homelessness would exceed normative expectations. Furthermore, we expected that poorer cognitive performance would be associated with poorer performance-based functional capacity.

Method

One hundred clients residing at the Father Joe′s Village homeless shelter in San Diego between February 2012 and March 2013 participated in the study. The 100 study participants represent 16% of residents informed about the study (n=626); 175/626 contacted the study team, 126/175 were eligible and scheduled for testing, with 26 lost to follow-up or refusal to participate. Inclusion criteria were: 1) aged 18–89 years old, 2) able to complete testing in English, and 3) able to provide voluntary informed consent. The University of California, San Diego, Institutional Review Board and Father Joe’s Village approved all study procedures.

Immediately following informed consent, the participants were asked brief questions regarding recent drug use (i.e., time since last use and drug type) to determine whether same-day neuropsychological testing was contraindicated. The neuropsychological and functional battery was then administered by trained study staff at the shelter. The entire evaluation took 60–90 minutes. Participants received a $20 gift card as compensation for their time.

Demographic and clinical characteristics were obtained via participant self-report and review of the participants’ shelter records (see Table 1). The shelter utilized the Psychiatric Diagnostic Screening Questionnaire (PDSQ; 6) to assess for psychiatric diagnoses and current symptoms, Simple Screening Questionnaire (7) to assess substance use history, and the Test of Adult Basic Education (8) to determine grade-level estimates of academic skill in reading, math, and language.

TABLE 1.

Sample characteristics and cognitive and functional capacity normative score comparisons (n=100)

Sample characteristics	Range	N or M±SD	%	t	p	% Impaired
Demographic characteristics
Age, years (M±SD)	18–66	48.9±9.2
Female		19	19
Education, years (M±SD)	0–18	11.7±2.2
Hispanic/Latino		10	10
Non-Caucasian		35	35
Ever married		14	14
Veteran		52	52
Lifetime # times in jail/prison	0–51	4.4±7.8
Tests of Adult Basic Education (TABE)
Reading grade level estimate	0.7–12.9	10.1±3.2
Language grade level estimate	0–12.9	7.8±3.9
Math grade level estimate	2.3–12.9	8.0±3.2
Clinical characteristics
Alcohol – years since last use (M±SD)	0–39	2.7±6.6
Drugs – years since last use (M±SD)	0–57.7	6.4±11.1
SSI-SA total (M±SD)	0–14	2.0±3.3
PDSQ total score (M±SD)	0–113	19.6±26.5
Test scores (M±SD)+						<1SD	<1.5SD
Functional capacity
UPSA-B		7.1±3.2		−9.337	<0.001	48%	37%
Neuropsychological measures
WRAT-4 Reading		92.4±13.8		−5.533	<0.001	23%	11%
WASI Matrix reasoning		49.9±11.7		−0.094	0.925	21%	13%
WASI Vocabulary		46.1±11.5		−3.370	0.001	22%	15%
FSIQ		97.7±16.1		−1.432	0.155	21%	12%
WAIS-IV Coding		7.8±2.8		−7.903	<0.001	30%	19%
						<26	<23
MoCA raw score		23.9±3.8		−9.384	<0.001	65%	30%

TABE: n=72; SSI-SA: Simple Screening Instrument for Substance Abuse, n=98; possible scores range from 0–14, with higher scores indicating greater degree of risk for substance abuse; PDSQ: Psychiatric Diagnostic Screening Questionnaire, n=94; possible scores range from 0–125, with higher scores indicating greater symptomatology; WRAT-4 = Wide Range Achievement Test – Fourth Edition; WASI = Wechsler Abbreviated Scale of Intelligence; FSIQ = Full Scale Intelligence Quotient; WAIS-IV = Wechsler Adult Intelligence Scale IV; MoCA = Montreal Cognitive Assessment; UPSA-B = UCSD Performance-based Skills Assessment – Brief. The WRAT-4 Word Reading subtest and FSIQ are expressed as standard scores (mean=100, SD=15); the WASI Matrix Reasoning and Vocabulary subtests are expressed as T scores (mean=50, SD=10); the WAIS-IV Coding subtest and UPSA-B are expressed as scaled scores (mean=10, SD=3); the MoCA score is expressed as a raw score (range 0–30). Higher scores on all tests signify better performance.

⁺df=99

The reading subtest from the Wide Range Achievement Test – Fourth Edition (WRAT-IV) was used to estimate premorbid IQ. The two-test version of the Wechsler Abbreviated Scale of Intelligence (WASI) was used to assess Full Scale Intelligence Quotient. The Coding subtest from the Wechsler Adult Intelligence Scale - Fourth Edition (WAIS-IV) was given as an estimate of processing speed. Finally, the Montreal Cognitive Assessment (MoCA) was given as a global cognitive screening test for mild cognitive impairment (9). The UCSD Performance-based Skills Assessment – Brief (UPSA-B; 10) was used to objectively measure financial and communication skills in role-play scenarios. Total scores range from 0 to 100, with higher scores reflecting better performance. Scaled scores were derived from the normative profile of the UPSA-B for comparison (11).

Cognitive impairment frequencies were classified using two cutoffs: scores >1 standard deviation below the mean and >1.5 standard deviations below the mean. Additionally, χ² tests assessed whether our sample’s cognitive/functional performance on each test differed from an expected level of impairment (<1 SD; <16^th percentile) in the population. An established cut-off score of <60 on the UPSA-B was used to examine the rates of individuals that would not be expected to be able to live independently (10). Normative scores in the current sample were compared to 50^th percentile normative scores for each test using one sample t-tests. Average performance-based functional capacity scaled scores were compared to mean values in the normative sample for the UPSA-B (11). One sample t-tests were also used to compare the current sample’s mean value on the MoCA to a published mean value in a normative sample (9). The originally recommended cutoff score of 26 was utilized to identify the proportion of participants who would be classified as having at least mild cognitive impairment (9). Mild cognitive impairment rates were also calculated using a more conservative MoCA cutoff score of 23, which is associated with improved false positive rate and overall diagnostic accuracy (12).

Results

Sample characteristics are detailed in Table 1. On average, participants reported being homeless at least 3.4±3.8 times over their lifetime, with 64/100 having had more than one episode of homelessness. At shelter entry, 29/100 met the HUD criteria for chronic homelessness (i.e., either continually homeless for 1 year or at least four episodes of homelessness in the past 3 years). Including their current shelter stay, participants had stayed in transitional housing 1–15 times previously (Mean=2.5±2.8).

Table 1 presents the mean and standard deviations the cognitive and functional capacity measures administered, as well as the one-sample t-test comparisons of each test to the 50^th percentile normative score (or the normative sample mean raw score, where indicated). Estimated premorbid IQ (92.4±13.8) was significantly less than the average standard score of 100 (p<0.001), but was still well within the average range (90–109). The average WASI FSIQ (97.7±16.1) was within the average range and not significantly different from the average standard score (p=0.155). However, 11/100 met the cognitive criteria for intellectual disability (FSIQ ≤75; DSM-5). Participants’ performance on both Matrix Reasoning (49.9±11.7) and Vocabulary (46.1±11.5) subtests of the WASI were in the average range, with only the Vocabulary T-score significantly less than the 50^th percentile T-score of 50 (p=0.001). Participants’ mean processing speed scores (7.8±2.8) were in the low average range, though just above the cutoff for mild impairment (scaled score <7) and were significantly less than the 50^th percentile scaled score of 10 (p<0.001). Based on the impairment criterion of >1SD below the mean (<16^th percentile in normative samples), 21/100 participants demonstrated impairments on both the WASI Matrix Reasoning subtest (χ²=0.83, p=.36) and FSIQ (χ²=0.83, p=.36), 22/100 on the WASI Vocabulary subtest (χ²=1.17, p=.28), and 23/100 on the WRAT-4 Reading subtest (χ²=1.56, p=.21), suggesting no clinically or statistically significant differences. However, 30/100 participants demonstrated practically and statistically significant impairment on the WAIS-IV Coding subtest (χ²=5.53, p=.02).

Participants’ mean MoCA total score (23.9±3.8) was significantly lower than normative expectation (p<0.001). Using the MoCA mild cognitive impairment cutoff of 26 (9), 65/100 would be classified as having at least mild cognitive impairment (χ²=49.82, p<.001). In contrast, using a MoCA cutoff of 23 (12), 30/100 of the current sample would be classified as having at least mild cognitive impairment.

Performance on the UPSA-B was in the low average range, and significantly less than the 50^th percentile scaled score of 10 (p<0.001), with 48/100 meeting criteria for impairment (χ²=23.53, p<.001) and 17/100 scoring <60, the cutoff for individuals not expected to be able to live independently. Higher estimates of premorbid IQ (r=.549), and better performance on the WASI Matrix Reasoning (r=.639), WASI Vocabulary (r=.552), WAIS-IV Coding (r=.416), and MoCA (r=.582) were associated with UPSA-B scores (ps<0.001).

Discussion

Results indicated higher rates of cognitive impairment in our sample than in the general population, particularly in the domains of crystallized knowledge and processing speed. Furthermore, we found high rates of functional impairment within our sample, and that poorer cognitive performance was strongly associated with poorer performance-based functional capacity, underscoring the need for routine cognitive screening and rehabilitation.

On average, participants’ premorbid IQ and current IQ were estimated to be in the average range; however, 11% of the sample met the cognitive criteria for intellectual disability. Current IQ estimates were partly based on performance on a test of crystallized knowledge, which may explain the lack of difference between the two IQ estimates. Higher IQ in our sample relative to others (1) could be due to a substantial representation of homeless Veterans in our sample, a subgroup known to have mean IQ in the average range (13), probably in part due to Armed Services Vocational Aptitude Battery requirements disqualifying individuals with low IQs from military service. Rates of impairment on the brief cognitive screening measure (the MoCA) were 65% using the originally recommended cutoff of 26 (9), and 30% when using a cutoff score of 23 (12), both significantly higher than the general population. Overall, these findings are consistent with prior studies demonstrating that cognitive impairment is common within people who are homeless (1,2). On average, participants evidenced low average performance on processing speed (Coding), and 30% scored in the impaired range, almost double the rate of impairment seen in the general population. Prior studies have suggested that brief screening measures may be inadequate in capturing the significant cognitive impairment in this population (1) and that the Coding subtest of the WAIS may be a particularly useful test to integrate within routine care in service settings, given its sensitivity to brain injury and general cerebral integrity (14). Nevertheless, the study’s cross-sectional design precludes the interpretation of these impairments as an indication of decline from prior levels of functioning.

To our knowledge, this is the first study to characterize rates of functional capacity impairment within a sample of adults who are homeless and receiving shelter services. Nearly half the sample (48) met criteria for impairment on the UPSA-B, a performance-based functional capacity measure; 17% of the total sample scored below the cutoff of 60 on the UPSA-B, which is used to identify individuals who may be unlikely to live independently (10). Furthermore, consistent with previous findings (5), estimates of premorbid IQ and performance across all neurocognitive measures were directly associated with performance-based functional capacity.

Our use of a reliable and valid screening measure (MoCA) and additional neuropsychological tests advance knowledge regarding cognitive functioning in this population. With previous evidence suggesting that cognitive impairment rates range from 2–82% in people who are homeless (1), it is likely that true mild cognitive impairment rates of homeless individuals, as measured by a comprehensive neuropsychological battery, would lie somewhere in between our range of 20% to 65%. Of note, cognitive performance was not significantly associated with PDSQ-derived psychiatric diagnoses; these results will be published in a forthcoming paper. Overall, these findings underscore the need for targeted cognitive interventions to improve functional outcomes for this population. Evidence-based compensatory cognitive strategies could be easily integrated into routine care by behavioral health providers/clinicians in homeless shelters, given the availability of low-cost, manualized protocols. Integration of cognitive interventions in current healthcare and social services systems for homeless individuals is further supported by a recent longitudinal investigation reporting high prevalence and persistence of neurocognitive impairment in this population (15). Moreover, this study found no association between housing stability and changes in cognitive functioning over an 18-month period, suggesting that housing stability, while important, may not modify risk for enduring neurocognitive impairment.

Our study is limited in its cross-sectional design and self-selected sample. Those who may have had trouble navigating the system, for cognitive or other reasons, could have been less likely to enroll or more likely to drop out while waiting for their study appointment. Psychiatric diagnoses were based on a self-administered questionnaire. The study also excluded non-English-speakers, and the majority of our participants were men. Thus, cognitive and functional performance within women who are homeless remains relatively under-investigated. It may also be that adults experiencing homelessness are impaired in additional cognitive abilities not measured in the current study. Additionally, because sampling occurred at a single shelter where residents were able to stay for up to two years, results may not extend to unsheltered populations, individuals living in short-stay emergency shelters, or those housed by friends or relatives. Future investigations should consider longitudinal designs and the inclusion of executive functioning measures (e.g., cognitive flexibility, problem-solving, and planning), which may directly correlate with functional outcomes and homelessness risk.

Conclusions

Our results underscore the importance of routine, objective cognitive and functional capacity assessment to better identify individuals who could benefit from neurocognitive interventions. Early identification of such impairments could lead to relevant improvements in service, such as earlier assistance with benefit applications and more assistance with social services. Providing cognitive rehabilitation services to identified adults experiencing homelessness may also generalize to better functional skills, potentially improving homeless individuals’ ability to navigate service systems on their own, and longer-range outcomes, such as achieving and maintaining stable housing.

Highlights:

• The results showed that cognitive and functional impairments are more common in people experiencing homelessness as compared to the general population.

• Poorer cognitive functioning was associated with poorer functional skills, underscoring the need for psychosocial interventions to improve cognition and functioning.

• Understanding cognitive and functional impairment within the homeless population can improve clinical management and service delivery to improve housing and health outcomes.