What is a mental disorder? A perspective from cognitive-affective science

Area of Science:

• Philosophy of Medicine and Psychiatry
• Cognitive-Affective Science
• Psychiatric Nosology

Background:

• The definition of disease and disorder is a central issue in philosophy of medicine and psychiatry.
• Current psychiatric nosology, including the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) and the upcoming International Classification of Diseases, 11th Revision (ICD-11), necessitates clear disorder definitions.
• Advances in cognitive-affective science offer new perspectives on human categorization relevant to psychiatric disorders.

Purpose of the Study:

• To explore the implications of cognitive-affective science advances for understanding the category of psychiatric disorder.
• To examine the utility of medical and moral metaphors, particularly the concept of dysfunction, in defining psychiatric disorders.
• To discuss the application of evolutionary concepts to understand dysfunction in psychiatric disorders and aid nosological decisions.

Main Methods:

• Conceptual analysis of psychiatric nosology and diagnostic criteria.
• Application of cognitive-affective science principles to the categorization of mental disorders.
• Examination of medical metaphors, focusing on dysfunction and evolutionary perspectives, to inform diagnostic debates.

Main Results:

• The category of mental disorder exhibits graded boundaries and can be conceptualized through medical or moral metaphors.
• The concept of dysfunction, especially when viewed through an evolutionary lens, is a key element in medical metaphors for disorders.
• While dysfunction is clear in typical disorders, atypical disorders present debates regarding the presence and extent of dysfunction, necessitating rational arguments for inclusion and boundary setting.

Conclusions:

• Rational arguments are essential for deciding the inclusion and boundaries of psychiatric entities in nosologies.
• Ongoing debate regarding diagnostic validity, clinical utility, and underlying values is appropriate for difficult-to-decide cases.
• Case examples from anxiety and obsessive-compulsive disorders illustrate the complexities of delineating normal from abnormal, classifying anxiety, and structuring disorder categories.