This study examines neurocognitive functioning in a large, well-characterized sample of homeless adults with mental illness and assesses demographic and clinical factors associated with neurocognitive performance.

A total of 1500 homeless adults with mental illness enrolled in the At Home Chez Soi study completed neuropsychological measures assessing speed of information processing, memory, and executive functioning. Sociodemographic and clinical data were also collected. Linear regression analyses were conducted to examine factors associated with neurocognitive performance.

Approximately half of our sample met criteria for psychosis, major depressive disorder, and alcohol or substance use disorder, and nearly half had experienced severe traumatic brain injury. Overall, 72% of participants demonstrated cognitive impairment, including deficits in processing speed (48%), verbal learning (71%) and recall (67%), and executive functioning (38%). The overall statistical model explained 19.8% of the variance in the neurocognitive summary score, with reduced neurocognitive performance associated with older age, lower education, first language other than English or French, Black or Other ethnicity, and the presence of psychosis.

Homeless adults with mental illness experience impairment in multiple neuropsychological domains. Much of the variance in our sample's cognitive performance remains unexplained, highlighting the need for further research in the mechanisms underlying cognitive impairment in this population.