Summary: A major scientific review reveals a deep knowledge gap in how cognition is affected when schizophrenia and personality disorders occur together. Despite the high prevalence and severe outcomes tied to this dual diagnosis, only a small number of rigorous studies have ever examined cognitive functioning in this group.
Cognition is one of the strongest predictors of long-term recovery in schizophrenia, yet people with both conditions remain underrepresented in research. The findings highlight the urgent need for better cognitive assessment and more personalized treatment strategies.
Key Facts
- High Prevalence: Roughly 40% of people with schizophrenia also have a personality disorder.
- Severe Outcomes: Dual diagnosis is linked to worse symptoms, higher hospitalization, and elevated suicide risk.
- Research Gap: Fewer than a dozen high-quality studies currently examine cognition in this population.
Source: University of Montreal
A new study by a research team at Université de Montréal highlights a critical lack of knowledge about the cognitive profiles of people living with both schizophrenia and a personality disorder.
A comprehensive review of scientific literature from the past 24 years, published in Schizophrenia Research: Cognition, reveals that despite the high prevalence of this dual diagnosis (affecting approximately 40 per cent of people diagnosed with schizophrenia) and its association with unfavourable outcomes, the available data are surprisingly limited and fragmented.
“Our analysis shows a significant blind spot in current knowledge,” said Anouck Chalut, lead author of the study and a Psy. D. in neuropsychology from UdeM. “Little is known about cognition in people living with a personality disorder in addition to schizophrenia.”
Led by UdeM psychology professor Tania Lecomte—director of L’ESPOIR, a research laboratory in the Department of Psychology dedicated to improving treatments and services for people with severe mental disorders—the researchers combed through hundreds of scientific articles but found only 10 that met their criteria for scientific rigour.
“We found that the existing research is limited, fragmentary and sometimes contradictory, leaving clinicians with few clear guidelines,” noted Chalut. This gap is consequential because cognition is the strongest predictor of recovery for individuals living with schizophrenia, she said.
Significant health challenges
The combination of schizophrenia and a personality disorder presents considerable challenges, including more severe psychotic symptoms, serious functional impairment, reduced compliance with medication, more frequent hospitalization and increased risk of suicide.
Despite these challenges, people with this dual diagnosis are often excluded from clinical studies or grouped together with patients who have only schizophrenia.
“Our findings underscore the need to improve our understanding of these individuals and focus on their cognitive profiles to support functional recovery, given that cognition plays a decisive role in that process,” said Chalut.
The study offers concrete recommendations for both clinicians and researchers, including systematic screening for symptoms of personality disorders in people living with schizophrenia and the use of standardized tools to characterize cognitive profiles in this population.
The research highlights the need for further investigation into adapting treatments and therapies to the specific needs of these individuals, who are often overlooked in current research, the study team argues.
Approaches such as cognitive remediation – which aims to mitigate the effects of cognitive deficits and support strategies to strengthen impaired mental abilities, including memory, attention and problem-solving – could prove useful, the researchers believe.
Key Questions Answered:
A: About 40% of people diagnosed with schizophrenia also meet criteria for a personality disorder.
A: It is linked to worse symptoms, poorer functioning, higher suicide risk, and reduced treatment adherence.
A: Clear, consistent data on cognitive functioning in people with both conditions.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this schizophrenia and personality disorders research news
Author: Julie Gazaille
Source: University of Montreal
Contact: Julie Gazaille – University of Montreal
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Cognitive deficits in individuals with comorbid personality disorder and schizophrenia: A scoping review” by Tania Lecomte et al. Schizophrenia Research: Cognition
Abstract
Cognitive deficits in individuals with comorbid personality disorder and schizophrenia: A scoping review
Objective
It is estimated that approximately 40 % of individuals diagnosed with schizophrenia also meet the diagnostic criteria for a personality disorder. This comorbidity is associated with an unfavorable prognosis for the illness.
Given that cognition is currently the best predictor of recovery, this study aims to characterize the cognitive profiles of individuals with comorbid personality disorders and schizophrenia by reviewing literature from the past 24 years.
We sought to determine whether the cognitive deficits differed from that of individuals with only a schizophrenia diagnosis, and to further characterize these differences.
Method
Articles were gathered from PubMed, Google Scholar, Web of Science, PsychInfo, PsychNet, MedLine, and EMBASE. They were selected based on the following inclusion criteria: (a) use of neuropsychological or social cognition measures, (b) explicit mental disorder diagnosis established using validated diagnostic tools, (c) participants with a comorbid personality disorder and schizophrenia diagnosis, and (d) results of neuropsychological measures specific to participants with this type of comorbidity.
Results
A total of 10 articles were included. Of these, six clinically established a personality disorder diagnosis, while five measured traits associated with various personality disorders. Due to the heterogeneity of methodologies across the studies, no statistical conclusions could be drawn.
Discussion/conclusion
Our review did highlight a greater presence of studies on antisocial personality, with few on other personality disorders or traits. Given the high comorbidity of personality disorders in schizophrenia, and the important impact of cognition on functioning, including social cognition, more studies are warranted. Recommendations for both clinicians and researchers are proposed.
