Schizophrenia and personality disorders are the most disabling mental health conditions to live with, according to scientists from the University of Queensland.

A Danish-Australian research team has studied a cohort of 6.9 million Danish residents in the Danish Psychiatric Central Research Register to understand the burden of disability associated with 18 mental and substance use disorders.

Professor John McGrath from UQ Queensland Brain Institute said the data was used to develop a new method for measuring disability that took comorbidities into account.

“Traditionally the impact of mental disorders has been presented for an entire nation, but in this study, we focused on people with different types of mental and substance use disorders at an individual level,” he said.

“We found that schizophrenia and personality disorders were the most disabling mental conditions and showed how disorders like autism, anxiety disorders and schizophrenia contribute to disability at different ages.

“Our new measure known as the Health Loss Proportion (HeLP) allows us to measure the average disability for different disorders at the individual level, which means that individuals who experience more inherent disability, and more comorbid conditions, will have a higher HeLP weighting, and therefore a higher measure of disability.”

He said the new method complemented methods being used by the Global Burden of Disease Study to help policymakers and clinicians plan health system responses.

“The study uses top-down summary statistics to estimate the impact of mental disorders on societies, while we have used a ‘bottom-up’ method based on Danish registers to estimate how mental disorders impact individuals across their life span,” McGrath said.

The team hopes that future register-based studies will create new knowledge about how comorbidity contributes to global disease burdens and apply this new method to disorders of interest.

“People with mental disorders lead valued and productive lives, despite a lack of social and economic support for their unmet needs and we hope our findings ensure more disabling disorders are given adequate attention, support, and funding.”

The research is published in Lancet Psychiatry