Majority of homeless adults with mental illness have high rates of cognitive deficits

The study-believed to be the largest of its kind -assessed neurocognitive functioning indicators such as mental processing speed, verbal learning and memory in 1,500 homeless adults in five Canadian cities.

The findings were published online by the journal Acta Psychiatrica Scandinavica.

"This points to an often unrecognized problem for the segment of Canada's homeless population that suffers from mental illness," said Dr. Vicky Stergiopoulos, chief of psychiatry at St. Michael's Hospital and a scientist in its Centre for Research on Inner City Health.

"These are the skills that people need to follow treatment or support recommendations, maintain housing stability or successfully complete day-to-day tasks."

Each year up to 200,000 Canadians are homeless. The prevalence of mental illness among homeless individuals is much higher than the rest of the population, with more than 12 per cent suffering from severe mental illness, 11 per cent having mood disorders and close to 40 per cent reporting alcohol and drug addictions.

All of the participants in Dr. Stergiopoulos' study experienced mental illness. About half met criteria for psychosis, major depressive disorder and alcohol or substance abuse, and nearly half had experienced traumatic brain injury.

Older age, lower education, psychotic illness, being a visible minority and having a native language other than English or French were associated with poorer cognitive performance; however these indicators could explain only part of the neurocognitive difficulties observed in this study. Traumatic brain injury and substance abuse were not associated with lower cognitive functioning.

"The data doesn't help us to predict whether someone will have cognitive challenges, but it does show that if they experience homelessness and mental illness, it's very likely," said Dr. Stergiopoulos. "It adds to our understanding about why people may have difficulty accessing or keeping housing."

Dr. Stergiopoulos noted the study is important for those who work directly with disadvantaged populations because it highlights that adaptations and improvements need to be made to treatment and support options. Lack of engagement is not necessarily because someone doesn't want help, but may be because they don't understand how to access or make use of it.

"Front-line staff may need more training in how they work with this population," said Dr. Stergiopoulos. "It reinforces the necessity to understand the needs and strengths of disadvantaged populations so that we can help address them."

In a series of tests to assess neurocognitive performance, seven of 10 participants experienced problems with verbal learning and memory, and four of 10 experienced problems with speed of information processing and executive functioning, an umbrella term for cognitive processes such as reasoning, task flexibility, problem solving and planning and execution.

"While cognitive remediation practices are in place in some specialty settings, we need to design better strategies that include programs for homeless people," said Dr. Stergiopoulos.