Major Psychological Disorders: Clinical Features, Diagnostic Criteria & Etiology

The systematic study of major clinical disorders requires precise diagnostic acumen, familiarity with empirical symptom criteria, understanding of underlying neurobiological and psychological mechanisms, and clear differential diagnosis. In the National Testing Agency (NTA) CUET PG Psychology examination (HUQP20), psychopathology questions emphasize:

1. Operational criteria, durations, and core symptom thresholds in DSM-5-TR and ICD-11.
2. Differentiation between related disorders (e.g., Panic Disorder vs. GAD, Bipolar I vs. Bipolar II, PTSD vs. Acute Stress Disorder, Conversion Disorder vs. Illness Anxiety Disorder).
3. The distinction between Positive and Negative Symptoms of Schizophrenia and the Dopamine Hypothesis.
4. Established cognitive and behavioral theories of etiology (e.g., Beck's Cognitive Triad, Seligman's Learned Helplessness, Mowrer's Two-Process Theory, George Brown's Expressed Emotion).

1. Anxiety Disorders

Anxiety is an anticipatory, future-oriented mood state accompanied by somatic tension, whereas fear is an immediate alarm reaction to present danger governed by the sympathetic nervous system. In pathological anxiety, this alarm system fires aberrantly, chronically, or disproportionately to environmental threat.

1. Generalized Anxiety Disorder (GAD)

• Core Diagnostic Hallmark: Excessive, uncontrollable anxiety and worry (apprehensive expectation) occurring more days than not for at least 6 months, across multiple domains (finances, health, family, work).
• Symptom Criteria (DSM-5-TR): Must exhibit at least 3 of 6 somatic-cognitive symptoms for $> 6$ months (only 1 item required in children):
  1. Restlessness or feeling keyed up or on edge
  2. Being easily fatigued
  3. Difficulty concentrating or mind going blank
  4. Irritability
  5. Muscle tension (the most distinguishing physical hallmark of GAD)
  6. Sleep disturbance (difficulty falling/staying asleep, or restless sleep).
• Etiological Mechanisms:
  • Neurobiology: Hypofunction of the inhibitory neurotransmitter GABA (gamma-aminobutyric acid). Underactive GABA-A receptor binding fails to inhibit hyperactive amygdalar-prefrontal fear circuits.
  • Cognitive Model (Borkovec): Worry acts as an internal cognitive avoidance strategy. Borkovec demonstrated that worry is primarily verbal/linguistic (rather than imaginal); engaging in abstract verbal worry dampens somatic autonomic arousal and insulates the individual from processing deeper, threatening emotional imagery.

2. Panic Attack and Panic Disorder

• Panic Attack: An abrupt surge of intense fear or intense discomfort reaching a peak within 10 minutes, accompanied by at least 4 of 13 physical/cognitive symptoms:
  • Autonomic: Palpitations/tachycardia, sweating, trembling, shortness of breath, feeling of choking, chest pain, nausea/abdominal distress.
  • Vestibular/Sensory: Dizziness/lightheadedness, paresthesias (numbness/tingling), chills or hot flashes.
  • Cognitive: Derealization (unreality) or depersonalization (detachment), fear of losing control/"going crazy", and fear of dying.
• Panic Disorder:
  • Characterized by recurrent, unexpected panic attacks.
  • At least one attack must be followed by $\ge 1$ month of persistent concern about having additional attacks, worry about implications (e.g., cardiac arrest), or significant maladaptive behavioral changes (e.g., avoiding exertion).
• Cognitive Model (David M. Clark): Panic arises from the catastrophic misinterpretation of benign bodily sensations (e.g., normal sinus tachycardia perceived as an impending fatal myocardial infarction), creating a positive feedback loop of escalating panic.
• Neurobiology: Hypersensitivity of the "suffocation alarm system" in the brainstem (medullary respiratory center) and hyperresponsiveness of the locus coeruleus (the brain's primary norepinephrine factory).

3. Agoraphobia

• DSM-5 Independence: In DSM-IV, agoraphobia was coded primarily as a specifier of Panic Disorder. In DSM-5, Agoraphobia is an independent, standalone diagnosis.
• Diagnostic Criteria: Marked fear or anxiety regarding at least 2 of the following 5 settings for $\ge 6$ months:
  1. Using public transportation (buses, trains, planes)
  2. Being in open spaces (parking lots, bridges, marketplaces)
  3. Being in enclosed spaces (shops, cinemas, theaters)
  4. Standing in line or being in a crowd
  5. Being outside of the home alone.
• Underlying Apprehension: Fear is rooted in thoughts that escape might be difficult, or help might not be available, in the event of developing panic-like, incapacitating, or humiliating symptoms.

2. Obsessive-Compulsive and Related Disorders (OCRD)

Decoupled from Anxiety Disorders in DSM-5, OCRD conditions are characterized by repetitive intrusive cognitions and behavioral compulsions driven by cortico-striato-thalamo-cortical (CSTC) neurocircuitry loops.

Obsessive-Compulsive Disorder (OCD)

• Obsessions: Recurrent, persistent thoughts, urges, or mental images experienced as intrusive and unwanted (ego-dystonic), causing marked anxiety. The individual attempts to ignore, suppress, or neutralize them.
• Compulsions: Repetitive overt behaviors (handwashing, checking, ordering) or covert mental acts (counting, silent praying, repeating words) performed in rigid response to an obsession, designed to prevent dread or reduce distress. Compulsions are either not realistically connected to the feared outcome or are grossly excessive.
• Time Threshold: Must consume $> 1$ hour per day or cause clinically significant social/occupational impairment.
• Insight Specifiers: Rated as With good or fair insight, With poor insight, or With absent insight / delusional beliefs.
• Neurobiology of OCD: Hyperactivity within the Cortico-Striato-Thalamo-Cortical (CSTC) loop—specifically involving the Orbitofrontal Cortex (OFC) (which detects errors and initiates alarm), the Anterior Cingulate Cortex (ACC) (affective distress), and the Caudate Nucleus of the dorsal striatum (which fails to filter or gate the repetitive primitive impulses relayed to the thalamus). Dysregulation of serotonin ($5\text{-HT}$) and glutamate is prominent.

3. Trauma- and Stressor-Related Disorders

PTSD vs. Acute Stress Disorder (ASD)

DSM-5 Diagnostic Architecture for PTSD ($\text{Duration} > 1 \text{ month}$):

1. Criterion A (Traumatic Exposure): Directly experiencing, witnessing in person, learning that a close relative/friend experienced violent/accidental death, or repeated extreme exposure to aversive details of trauma (e.g., first responders).
2. Criterion B (Intrusions — $\ge 1$ required): Recurrent distressing memories, traumatic nightmares, dissociative flashbacks (acting/feeling as if trauma is recurring), or intense physiological reactivity to trauma cues.
3. Criterion C (Persistent Avoidance — $\ge 1$ required): Active avoidance of trauma-related internal thoughts/feelings OR external reminders (people, places, conversations).
4. Criterion D (Negative Alterations in Cognitions & Mood — $\ge 2$ required): Inability to recall key aspects of trauma (dissociative amnesia), persistent distorted blame of self or others, persistent negative emotional states (fear, guilt, shame), marked anhedonia, alienation from others, or persistent inability to experience positive emotions.
5. Criterion E (Alterations in Arousal & Reactivity — $\ge 2$ required): Irritable behavior and angry outbursts, reckless or self-destructive behavior, hypervigilance, exaggerated startle response, concentration deficits, and sleep disturbance.

4. Depressive Disorders and Bipolar Spectrum