Comorbidity, Prevalance and Trends

General Definition of Comorbidity  Historical Origins (Feinstein, 1970)  General Definition: Two or more physical illnesses, psychological conditions or a mix of the two  Rule rather than the exception  Distinguish:  Covariation  Co-occurrence

Overview of the NCS, NCS- R   National Comorbidity Survey ( ), First nationally representative survey of mental disorders using research diagnostic interviews using DSM-III-R criteria  National Comorbidity Survey-Replication ( ), N = 10,000, used DSM-IV criteria  Follow up on disorders from the first NCS and to explore particular questions in further depth

Rates of Comorbidity  Nearly half of all people with a mental disorder have two or more disorders  More than half of people with a substance use disorder and more than 75% of those within treatment for substance abuse or dependence als meet criteria for a mental disorder  Individuals frequently meet criteria for three or more disorders  Disorders may have indirect or direct causes— more on this later

Modeling Comorbidity: Krueger and Markon  Associated Liabilities Models: A liability is an indirectly observed or latent propensity to develop directly observed or manifest disorders  What are some examples of liabilities?

Modeling Comorbidity: Krueger and Markon  Associated Liabilities Model

Modeling Comorbidity: Krueger and Markon  Multiformity Model

Modeling Comorbidity: Krueger and Markon  Causation Model

Modeling Comorbidity: Krueger and Markon  Independence Model

Modeling Comorbidity: Krueger and Markon  Hypothetical Multivariate Model

Dual Diagnosis: An application of Comorbidity  Berken’s Fallacy: Individuals with multiple disorders are more likely to seek treatment so that estimates of the prevalence of comorbid disorders will be higher in clinical samples  Inpatient vs Outpatient status  Chronicity of Illness  Severity of Illness

Methodological issues contd  Definitional issues vary from problem use of a substance to abuse or dependence  Which substances are included in the definition makes a difference  Disconnected areas of study

Effect of Comorbidity  Comorbidity affects a disorder’s course prognosis, assessment, treatment and outcome  Dual diagnosis: When a person meets criteria for one or more Axis I or Axis II mental disorders and meet criteria for one or more substance use disorders  Individuals with a lifetime history of a mental illness are 2.3 times more likely to have lifetime alcohol use disorder and 4.5 times more likely to have a substance use disorder

Disorders with Highest Comorbidities  ASP (84%)  Bipolar Disorder (61%)  Schizophrenia (47%)  Panic (36%)  OCD (33%)  MDD (27.2%)  Men and women with PTSD were 5 and 1.4 times more likely to have a drug use disorder than those without  Overall mental disorders yield at least double the risk of a lifetime alcohol or drug use disorder

Impact of Dual Diagnosis  How are patients affected?  Assessment issues

Underlying theories  Common Factors  Secondary Substance Abuse  Secondary Psychiatric Disorder  Bidirectional Models

Prevalence and Treatment of Disorders  No notable change in the prevalence or severity of mental disorder in the United States between or between  Most treatment for disorders falls below the minimal standards of quality  Treatment typically brief (affects duration of particular disorder more than prevalence of mental disorder  Most treatment delivered in the medical sector for disorders below clinical threshold.

Overall Rates of Multimorbidity  It is not uncommon for patients to have 3 or more disorders: 14% of the NCS sample had 3 or more diagnoses and these respondents accounted for almost 90% of the severe 12 month disorders and well over half of the lifetime and 12 month diagnoses in the sample.