Risk Factors for Psychosis in Homeless People – The HOTEL Study
This article is based on the talk by Prof William Honer at RCPsychIC 2019. Prof Honer is interested in translational research with the goals of linking understanding of the mechanisms of serious mental illness to new approaches to treating patients. Current projects focus on abnormalities of synapses in schizophrenia and ageing, studies of response to antipsychotic drug treatment in patients, and investigating the overlap of mental illness, addiction, and viral infection in people living in single-room occupancy hotels.
- Community-based studies of high-risk participants provide an understanding of how psychotic symptoms originate. The Hotel Study was set up to determine risk factors for psychosis in people living in precarious housing or homelessness in Vancouver.[Honer et al. 2017]
- The researchers mapped the housing locations of patients presenting for 552,062 visits to the catchment hospital emergency department (2005-2013).
- Participants were recruited from single room occupancy (SRO) hotels (n = 310) and the Downtown Community Court (n = 65) between 2008 and 2012.
- The investigation was designed as a longitudinal study and baseline assessments were made of addiction, mental illness, viral infection, and neurological illness. Participants had a monthly follow-up for 1-10 years where health, ability to access health care services, change in housing and ability to function were assessed.
- The primary outcome was the categorical presence or absence of clinically relevant symptoms described in DSM-V as “psychotic features” – features characterised by delusions, hallucinations, and formal thought disorder. Key PANSS items were delusions, conceptual disorganisation, hallucinations, suspiciousness, and unusual thought content.
- The approach was to look at time-invariant risk factors over time to determine the importance of past psychotic disorder (61%), early-life trauma (79%), past traumatic brain injury (10%), and homelessness by the age of 18 (31%).
- Time variant risk factors were also evaluated; non-prescribed substance use, recent traumatic events, and recent homelessness in the past year (20%). A high number of participants experienced trauma in at least one month over the year (82%).
- Longstanding time-invariant risk factors contribute to the risk of expressing psychotic symptoms, as do recent and concurrent experiences or exposures.
- For participants with multiple substance use, acute effects were observed for alcohol, cannabis, and methamphetamine with possible longer-lasting effects of methamphetamine. All three substances showed effects related to the number of days of use. The effects of cocaine and opioids were not as prominent in this sample.
- Mapping confirmed the association between poverty and a greater number of emergency visits related to substance use and mental illness.
- There are challenges associated with health delivery in this cohort of an impoverished neighbourhood in Vancouver, Canada. Illness-specific delivery systems had little impact on multimorbidity, concluding that new models of care need to be implemented.