Cognitive profiles and associated structural brain networks in a multimorbid sample of marginalized adults

Using serial position effects to investigate memory dysfunction in homeless and precariously housed persons

Background: Homeless and precariously housed persons exhibit significant memory impairment, but the component processes underlying memory dysfunction have not been explored. We examined the serial position profile (i.e., primacy and recency effects) of verbal memory and its neuroanatomical correlates to identify the nature of memory difficulties in a large cohort of homeless and precariously housed adults. Method: The sample included 227 community-dwelling homeless and precariously housed adults. Serial position scores (primacy, middle, recency) were computed using the Hopkins Verbal Learning Test-Revised. Paired sample t-tests were used to compare percent recall from each word list region. Age-adjusted correlations assessed associations between serial position scores and other cognitive domains (attention, processing speed, executive functioning). Regression analyses were conducted to examine regional brain volumes of interest (hippocampus, entorhinal cortex, dorsolateral prefrontal cortex [DLPFC]) and their differential associations with serial position scores. Results: The serial position profile was characterized by a diminished recency effect in relation to the primacy effect. Serial position scores positively correlated with sustained attention and cognitive control. Larger hippocampal volume was associated with better primacy item recall. DLPFC volume was not associated with serial position recall after adjustment for false discovery rate. There were no associations between regional brain volumes and recency item recall. Conclusion: Our results suggest that commonly reported memory difficulties in homeless and precariously housed adults are likely secondary to a core deficit in executive control due to compromised frontal lobe functioning. These findings have implications for cognitive rehabilitation in this complex and vulnerable group.

Exploring and Mapping Screening Tools for Cognitive Impairment and Traumatic Brain Injury in the Homelessness Context: A Scoping Review

Cognitive impairment is common amongst people experiencing homelessness, yet cognitive screening and the collection of history of brain injury rarely features in homelessness service delivery practice. The purpose of this research was to scope and map strategies for screening for the potential presence of cognitive impairment or brain injury amongst people experiencing homelessness and identify instruments that could be administered by homelessness service staff to facilitate referral for formal diagnosis and appropriate support. A search was conducted across five databases, followed by a hand search from relevant systematic reviews. A total of 108 publications were included for analysis. Described in the literature were 151 instruments for measuring cognitive function and 8 instruments screening for history of brain injury. Tools that were described in more than two publications, screening for the potential presence of cognitive impairment or history of brain injury, were included for analysis. Of those regularly described, only three instruments measuring cognitive function and three measuring history of brain injury (all of which focused on traumatic brain injury (TBI)) may be administered by non-specialist assessors. The Trail Making Test (TMT) and the Ohio State University Traumatic Brain Injury Identification Method (OSU TBI-ID) are both potentially viable tools for supporting the identification of a likely cognitive impairment or TBI history in the homelessness service context. Further population-specific research and implementation science research is required to maximise the potential for practice application success.

Dynamic networks of psychotic symptoms in adults living in precarious housing or homelessness

BACKGROUND

People living in precarious housing or homelessness have higher than expected rates of psychotic disorders, persistent psychotic symptoms, and premature mortality. Psychotic symptoms can be modeled as a complex dynamic system, allowing assessment of roles for risk factors in symptom development, persistence, and contribution to premature mortality.

METHOD

The severity of delusions, conceptual disorganization, hallucinations, suspiciousness, and unusual thought content was rated monthly over 5 years in a community sample of precariously housed/homeless adults (n = 375) in Vancouver, Canada. Multilevel vector auto-regression analysis was used to construct temporal, contemporaneous, and between-person symptom networks. Network measures were compared between participants with (n = 219) or without (n = 156) history of psychotic disorder using bootstrap and permutation analyses. Relationships between network connectivity and risk factors including homelessness, trauma, and substance dependence were estimated by multiple linear regression. The contribution of network measures to premature mortality was estimated by Cox proportional hazard models.

RESULTS

Delusions and unusual thought content were central symptoms in the multilevel network. Each psychotic symptom was positively reinforcing over time, an effect most pronounced in participants with a history of psychotic disorder. Global connectivity was similar between those with and without such a history. Greater connectivity between symptoms was associated with methamphetamine dependence and past trauma exposure. Auto-regressive connectivity was associated with premature mortality in participants under age 55.

CONCLUSIONS

Past and current experiences contribute to the severity and dynamic relationships between psychotic symptoms. Interrupting the self-perpetuating severity of psychotic symptoms in a vulnerable group of people could contribute to reducing premature mortality.

Photo elicitation to explore health and social exclusion with rooming house residents in Ottawa, Canada

Little is known about how rooming house residents perceive how housing influences their health, despite higher morbidity and premature death compared to other Canadians. The social exclusion framework of the Social Knowledge Exchange Network (SEKN) conceptualized by Popay et al. (2008) was used to investigate how rooming houses are linked to health among ten rooming house residents from six rooming houses in Ottawa, Ontario, Canada. Study activities included taking photos to show how living in a rooming house affects health, a community walk-about with the principal investigator, a focus group, and individual interviews. Thematic analysis revealed two broad themes: Housing is Health Care, and Just Managing Today. Findings suggest that structural inequalities and siloed care contribute to the health of rooming house residents, including the balance between poverty and desire to maintain housing, and how residents cope with this stress. If health care providers want to help alleviate the disparities in rooming house residents' health, they need to broaden the lens through which health is conceptualized.

Neurocognitive health of older adults experiencing homelessness in Oakland, California

Background and objectives

The homeless population in the US is aging. Cognitive impairment is prevalent in this population, yet little is known about the neurologic etiologies of such impairment. Addressing this gap in knowledge is important because homeless older adults with cognitive impairment due to neurodegenerative disease may need lifelong tailored support to obtain and maintain housing. In this study, we characterized the neurocognitive health of a sample of adults who experienced homelessness for the first time after age 50 using gold standard behavioral neurology examination practices.

Methods

We conducted a descriptive cross-sectional study of older adults who first experienced homelessness after age 50. We recruited our sample purposively from an ongoing longitudinal cohort study of adults who were aged 50 and over and homeless when they entered the cohort. For this sub study, we enrolled a convenience sample from those who reported their first episode of homelessness after age 50. We did not exclude individuals based on history of substance use. Neurologists conducted a structured neurocognitive history intake, neurological examination, neuropsychological evaluation, and functional assessment between November 2020 and February 2021. We screened all participants for neurocognitive disorders using gold standard clinical research diagnostic criteria.

Results

We evaluated 25 participants, most were men (76%) and Black (84%), with a median age of 61 years. The most common neurocognitive complaints included deficits in recent episodic memory (n = 15, 60%), executive functions (n = 13, 52%), and behavior/mood, with apathy being the most common complaint (n = 20, 80%). Neuropsychological testing revealed a high prevalence of socioemotional deficits (n = 20, 80%). Common neurological examination deficits included difficulties with coordination, such as impaired Luria task (n = 16, 64%), signs of distal peripheral neuropathy (n = 8, 32%), anosmia/hyposmia (n = 4, 21%), and signs of mild Parkinsonism (n = 5, 20%). The most common diagnoses were MCI (n = 7, 28%), bvFTD (n = 4, 16%), AD (n = 4, 16%), and DLB (n = 2, 8%).

Discussion

Our findings suggest that neurocognitive concerns and examination deficits are common among older homeless adults. Specific neurocognitive disorders may be overrepresented in this population, particularly frontotemporal disorders. Longitudinal studies involving brain biomarkers are needed to characterize the neurocognitive health of this vulnerable population more precisely.

Altered Surface Area Covariance in the Mentalizing Network in Schizophrenia: Insight Into Theory of Mind Processing

BACKGROUND

Theory of mind (ToM), the cognitive capacity to attribute mental states to self and others, is robustly affected in schizophrenia. The neural substrates of ToM impairment have been largely studied with functional imaging, but little is known about structural abnormalities. We compared structural covariance (between-subjects correlations of brain regional measures) of magnetic resonance imaging-based cortical surface area between patients with schizophrenia and healthy control subjects and between schizophrenia subgroups based on the patients' ToM ability to examine ToM-specific effects on structural covariance in schizophrenia.

METHODS

T1-weighted structural images were acquired on a 3T magnetic resonance imaging scanner, and ToM was assessed with the Hinting Task for 104 patients with schizophrenia and 69 healthy control subjects. The sum of surface area was computed for 12 regions of interest selected and compared between groups to examine structural covariance within the often reported mentalizing network: rostral and caudal middle frontal gyrus, inferior parietal lobule, precuneus, and middle and superior temporal gyrus. High and low ToM groups were defined using a median split on the Hinting Task.

RESULTS

Cortical surface contraction was observed in the schizophrenia group, predominantly in temporoparietal regions. Patients with schizophrenia also exhibited significantly stronger covariance between the right rostral middle frontal gyrus and the right superior temporal gyrus than control subjects (r = 4.015; p < .001). Direct comparisons between high and low ToM subgroups revealed stronger contralateral frontotemporal covariances in the low ToM group.

CONCLUSIONS

Our results provide evidence for structural changes underlying ToM impairments in schizophrenia that need to be confirmed to develop new therapeutic perspectives.

Differential effects of cannabis exposure during early versus later adolescence on the expression of psychosis in homeless and precariously housed adults

Longitudinal studies of cannabis exposure during early adolescence in the general population frequently report an increased risk of subsequently developing psychotic symptoms or a psychotic illness. However, there is a dearth of knowledge about the effects of early cannabis exposure on psychosis in homeless and precariously housed adults, who represent a population afflicted with high rates of psychosis. The aim of the present study was to examine how early cannabis exposure (by age 15) compared to later first use (after age 15) affected the expression of adult psychosis in this population. Secondary measures of psychopathology, drug use, cognition and brain structure were also collected. 437 subjects were recruited from single room occupancy hotels in the urban setting of the Downtown Eastside of Vancouver, Canada. Psychiatric diagnoses were determined, and psychotic symptom severity was measured with the 5-factor PANSS. Participants completed a battery of neurocognitive tests, and brain structure was assessed using structural and diffusion tensor imaging MRI scans. Results indicated that early cannabis exposure was associated with an increased risk (OR = 1.09, p < .05) of developing substance induced psychosis, whereas later first use increased risk (OR = 2.19, p < .01) of developing schizophrenia or schizoaffective disorder. There was no group difference in neurocognitive function, although differences were observed in the lateral orbitofrontal cortex and white matter tract diffusivity. These findings indicate that early cannabis exposure in this population may increase the risk of developing drug associated psychoses, which could potentially be mediated in part through altered neurodevelopmental brain changes.

Characterization of Bodily Pain and Use of Both Prescription and Non-Prescription Opioids in Tenants of Precarious Housing

opioid use, which includes both prescribed and non-prescribed drugs, is relatively common amongst marginalized populations. Past research has shown that among those who use non-prescribed or diverted opioids recreationally, many were first exposed to the drug as prescribed pain medication. Objective: to better understand the relationship between pain and opioid use in tenants of precarious housing. Methods: in the present study, 440 individuals from a cohort living in homeless or precariously housed conditions in a neighborhood with high rates of poverty and drug use were interviewed for their bodily pain and opioid use. We examined the relationship between bodily pain levels, assessed using the Maudsley Addiction Profile questionnaire, and prescribed, non-prescribed and combined self-reported opioid use in the prior 28 days assessed using the Timeline Followback and Doctor-Prescribed Medication Timeline Followback questionnaires. Results: Analysis of the results indicated that sex (female), age (younger) and early exposure to opioids (≤ age 18) predicted current opioid use, but there was no association between current bodily pain levels and opioid use. Conclusions: these unexpected findings indicate the complex nature of the relationship between pain and opioid use in this population.

Cognitive decline and mortality in a community-based sample of homeless and precariously housed adults: 9-year prospective study

BACKGROUND

Homeless and precariously housed individuals experience a high burden of comorbid illnesses, and excess mortality. Cross-sectional studies report a high rate of cognitive impairment. Long-term trajectories have not been well investigated in this group.

AIMS

To longitudinally assess risks for premature and/or accelerated cognitive ageing, and the relationship with early mortality in homeless and precariously housed people.

METHOD

This is a 9-year community-based study of 375 homeless and precariously housed individuals from Vancouver, Canada. Annual cognitive testing assessed verbal learning and memory, and inhibitory control. Linear mixed-effects models examined associations between clinical risk factors (traumatic brain injury, psychotic disorders, viral exposure, alcohol dependence) and cognitive change over 9 years. Cox regression models examined the association between cognition and mortality.

RESULTS

Traumatic brain injury and alcohol dependence were associated with decline in verbal memory. Inhibitory control declined, independent of risk factors and to a greater extent in those who died during the study. Better inhibitory control was associated with a 6.6% lower risk of mortality at study entry, with a 0.3% greater effect for each year of life. For each one-point increase in the Charlson Comorbidity Index score at study entry, the risk of mortality was 9.9% higher, and was consistent across age. Adjusting for comorbidities, inhibitory control remained a significant predictor of mortality.

CONCLUSIONS

Findings raise the possibility of a premature onset, and accelerated trajectory, of cognitive ageing in this group of homeless and precariously housed people. Traumatic brain injury, alcohol dependence and cognition could be treatment priorities.