Chapter 35: Mood and Anxiety Disorders in Personality

Mood and Anxiety Disorders in Personality explores the deep-rooted historical and modern connections between personality and psychopathology, using a hierarchical structural framework for organizing these domains. Historically, the relationship was recognized in the doctrine of the four humours (e.g., phlegmatic, sanguine, choleric, melancholic), linking temperament to humoural imbalance, and later through the Darwinian-era degeneracy theory, which wrongly equated mental illness with a fundamental genetic inferiority, characterized by personality correlates like laziness and impulsivity. Modern empirical research, however, validates aspects of these early frameworks; for instance, Eysenck’s dimensional model connects personality traits like Neuroticism and Extraversion to the four humoural types. Following a period of independence, the fields re-integrated, promoting the perspective that personality disorders (PDs, coded as Axis II in the DSM system) are best understood not as distinct categories, but as extreme, maladaptive variants of general personality traits. This dimensional view helps explain the pervasive clinical problem of excessive co-occurrence observed among PDs and between PDs and Axis I clinical disorders, such as mood and anxiety disorders. A key achievement in unifying these fields is the integrated hierarchical model of personality (Markon et al., 2005), which proposes a structure moving from broad, higher-order factors like the Big Two (Alpha for general negative emotionality, Beta for general positive emotionality) down to the familiar Big Five traits (Neuroticism, Agreeableness, Conscientiousness, Extraversion, Openness). The structure of Axis I mood and anxiety disorders is also hierarchical, with models developed to account for their high rates of co-occurrence. The Tripartite Model (Clark and Watson, 1991) suggests that Negative Affectivity (NA) is a non-specific factor common to both anxiety and depression, while low Positive Affectivity (PA, or anhedonia) is relatively unique to depression, and Physiological Hyperarousal (PHY) is specific to disorders like panic disorder. More contemporary quantitative hierarchical models, driven by studies from Krueger and colleagues, posit that psychiatric disorders bifurcate into higher-order Internalizing disorders (mood and anxiety) and Externalizing disorders (e.g., substance use, antisocial PD). The internalizing dimension further divides into Fear disorders (like phobias and panic disorder) and Anxious-Misery or Distress disorders (like major depression and generalized anxiety disorder). Importantly, these hierarchical structures map onto the integrated personality framework: Internalizing disorders are strongly characterized by NA (Neuroticism), while Externalizing disorders are linked to Disinhibition (low Agreeableness and low Conscientiousness). Finally, the chapter addresses the crucial etiological question of how these domains relate, presenting non-mutually exclusive models such as the Vulnerability Model (personality increases disorder risk), the Scar Model (psychopathology causes permanent personality change), and the Common Cause Model (shared underlying factors like genetics).