Objective: To examine the comorbidity of Axis I and II disorders within a community-based sample of adults with schizophrenia.
Methods: The study was conducted using data from the National Epidemiologic Survey of Alcohol and Related Conditions. A diagnosis of schizophrenia was based on respondents' self-report that they had been diagnosed by a health professional with schizophrenia or a psychotic illness or episode (SPIE). Axis I disorders and Axis II personality disorders (PDs) were assessed using the Alcohol Use Disorders and Associated Disabilities Interview Schedule. Mental and physical quality of life were assessed using the Medical Outcomes Study Short Form 12 questionnaire.
Results: The prevalence of SPIE was 0.9%. We used multiple logistic regression to examine the association between the presence and absence of SPIE in Axis I and II mental disorders. Each of the Axis I and II mental disorders examined were significantly associated with a diagnosis of SPIE after controlling for age, sex, education, marital status, and household income.
Conclusions: Clinicians should be aware of the patterns and extent of psychiatric comorbidities that may exist in schizophrenia. Possible mechanisms of these associations are discussed.
Can J Psychiatry. 2009;54(7):477-486.
* Comorbid PDs are common among people diagnosed with SPIE, and these conditions may have implications for course of illness and clinical management.
* Treatment of people diagnosed with SPIE should include an evaluation for co-occurring substance use disorders.
* Concurrent clinical attention to the associated mood and anxiety syndromes in schizophrenia may be important for optimal outcomes.
* Schizophrenia was diagnosed through self-report.
* This study used cross-sectional community data.
* Not all Axis II PDs were examined.
Key Words: schizophrenia, epidemiology, DSM, mood, anxiety, personality, substance dependence, substance abuse
Abbreviations used in this article
APD antisocial personality disorder
AUDADIS Alcohol Use Disorder and Associated Disability Interview Schedule
DSM Diagnostic and Statistical Manual of Mental Disorders
MDD major depressive disorder
NESARC National Epidemiologic Survey of Alcohol and Related Conditions
PD personality disorder
SES socioeconomic status
SF short form
SPIE schizophrenia or a psychotic illness or episode
SUD substance use disorder
Schizophrenia is often a chronic, severely debilitating disorder with a poorer overall outcome compared with any other major mental illness.1 Suicide rates among people diagnosed with schizophrenia are abnormally high. 1-3 In addition, these people are more likely to fall into the lowest SES group, 1 have a significantly lower employment rate than people without schizophrenia,2,4 and are more likely to live in poverty than people with MDD, alcohol abuse, or alcohol dependence.5 Numerous studies have demonstrated high comorbidity with DSM-IV mood disorders,6-9 SUDs,3,7,10-12 PDs,7,13,14 and anxiety disorders.2,3,7,15-18 Even after adjusting for anxiety related to delusions or hallucinations, the relation between anxiety disorders and schizophrenia remains strong.19
Mood disorders are especially prevalent in patients with schizophrenia. One study of DSM-IV-diagnosed patients with schizophrenia found that nearly one-half (46%) met criteria for MDD at one or both follow-ups conducted 4.5 and 7.5 years after hospital discharge.20 SUDs appear to show the highest comorbidity with schizophrenia. The Epidemiologic Catchment Area Study included 20 291 people from within the United States and found that 47% of people with a diagnosis of schizophrenia had a co-occurring substance abuse or dependence disorder.21 Rates of comorbid SUDs are especially high in men6,22-24 and those diagnosed with panic attacks. …