Psychological Disorders: Classification, Personality, and Dissociative Disorders

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Defining & Classifying Psychological Disorders

Abnormal Psychology and Historical Approaches

Abnormal psychology is the scientific study of mental illness and maladaptive behavior. Throughout history, societies have attempted to understand and treat psychological disorders in various ways, often reflecting the prevailing cultural and scientific beliefs of the time.

Maladaptive behavior: Actions or tendencies that cause distress to oneself or others, impair daily functioning, or increase the risk of harm.
Historical treatments included trepanation (drilling holes in the skull to release 'evil spirits') and the establishment of asylums.
The medical model treats psychological disorders similarly to physical illnesses, focusing on symptoms, causes, and outcomes.
Early classification efforts, such as those by Emil Kraepelin, laid the groundwork for modern diagnostic systems.

Portrait of an early psychiatrist (blurred face) Historical painting depicting early psychological treatment (trepanation) Skull with evidence of trepanation Title page of 'A Treatise on Madness' by William Battie

Modern Classification: The DSM

The Diagnostic and Statistical Manual of Mental Disorders (DSM) is the primary system for classifying psychological disorders in North America. The current edition is DSM-5-TR, which organizes disorders by symptom clusters and recognizes the spectrum of severity.

Disorders are diagnosed based on specific criteria, but classification can be complicated by subjective judgments and stigma.
Some disorders, such as Asperger’s syndrome, have been reclassified under broader categories like autism spectrum disorder (ASD).
New diagnoses, such as prolonged grief disorder, reflect evolving understanding.
Problems with classification include defining what is truly 'maladaptive,' clinician bias, and the impact of labeling.

Bar graph showing the increase in the number of disorders across DSM editions

Applications of Diagnoses

Diagnoses of psychological disorders have important implications in various settings:

Classrooms: Diagnoses such as attention deficit/hyperactivity disorder (ADHD) help guide educational interventions but have also raised concerns about overdiagnosis and the influence of social media.
Courtrooms: Mental disorder diagnoses can be used in legal defenses, such as 'not guilty by reason of insanity' (M’Naghten rule).

Personality & Dissociative Disorders

Personality Disorders: Overview and Clusters

Personality disorders are enduring patterns of behavior, cognition, and inner experience that deviate markedly from cultural expectations, are inflexible, and lead to distress or impairment. The DSM groups these disorders into three clusters:

Table summarizing personality disorder clusters and key features

Cluster A: Odd, Eccentric Disorders

Paranoid Personality Disorder: Persistent distrust and suspicion of others, often interpreting their motives as malevolent.
Schizoid Personality Disorder: Detachment from social relationships and limited emotional expression.
Schizotypal Personality Disorder: Acute discomfort in close relationships, cognitive or perceptual distortions, and eccentric behavior.

Diagram of the superior temporal gyrus, relevant to schizotypal personality disorder Cycle diagram of paranoid cognitive biases and behaviors

Cluster B: Dramatic, Emotional, or Erratic Disorders

Borderline Personality Disorder (BPD): Instability in relationships, self-image, and emotions; impulsivity; intense fear of abandonment.
Narcissistic Personality Disorder (NPD): Grandiosity, need for admiration, and lack of empathy.
Histrionic Personality Disorder: Excessive emotionality and attention-seeking behavior.
Antisocial Personality Disorder (APD): Disregard for and violation of the rights of others, lack of empathy, and often criminal behavior.

Bar graph comparing physiological responses in controls and people with antisocial personality disorder Brain diagrams showing regions implicated in personality disorders

Cluster C: Anxious or Fearful Disorders

Avoidant Personality Disorder: Social inhibition, feelings of inadequacy, and hypersensitivity to negative evaluation.
Dependent Personality Disorder: Excessive need to be taken care of, leading to submissive and clinging behavior.
Obsessive-Compulsive Personality Disorder (OCPD): Preoccupation with orderliness, perfectionism, and control, distinct from obsessive-compulsive disorder (OCD).

Dissociative Disorders

Dissociative disorders involve disruptions in consciousness, memory, identity, or perception. The most well-known is Dissociative Identity Disorder (DID), formerly known as multiple personality disorder.

Dissociation: A disconnection between thoughts, identity, consciousness, and memory. Common experiences include daydreaming or being 'in the zone.'
DID: Characterized by the presence of two or more distinct personality states or identities, often linked to severe childhood trauma. The disorder remains controversial regarding its prevalence and causes.

Movie poster referencing dissociative identity disorder (DID)

References and Further Reading

DSM-5 Table of Contents: APA DSM-5 Contents
Yeung, A., Ng, E., & Abi-Jaoude, E. (2022). TikTok and Attention-Deficit/Hyperactivity Disorder: A Cross-Sectional Study of Social Media Content Quality. Canadian Journal of Psychiatry, 67(12), 899–906. https://doi.org/10.1177/07067437221082854