20.4 Psychological Disorders
Key Takeaways
- The DSM-5-TR is the current U.S. diagnostic manual; diagnoses are categorical but the NIMH Research Domain Criteria (RDoC) promote dimensional research frameworks.
- Anxiety disorders include generalized anxiety disorder, panic disorder, phobias, and social anxiety disorder; key features involve excessive fear and avoidance.
- Mood disorders include major depressive disorder and bipolar I/II disorders; suicide risk assessment is a clinical priority.
- Schizophrenia involves positive symptoms (hallucinations, delusions), negative symptoms (anhedonia, flat affect), and cognitive symptoms.
- The biopsychosocial model integrates genetic vulnerability, neurochemistry, psychological factors, and sociocultural stressors in disorder etiology.
Psychological Disorders on the PA-CAT
Quick Answer: The PA-CAT Bulletin of Information, rev. 20240815 expects you to recognize major DSM disorder categories—especially anxiety, mood, psychotic, personality, somatic, and dissociative disorders—and to reason about biopsychosocial etiology. Expect brief clinical vignettes asking for the most likely diagnosis or the defining feature.
Classification: The DSM
The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR) published by the American Psychiatric Association is the standard U.S. diagnostic manual. It uses categorical diagnoses with specifiers, severity ratings, and explicit diagnostic criteria. The NIMH Research Domain Criteria (RDoC) is a complementary dimensional research framework that cuts across DSM categories by examining neurobiological dimensions (negative valence, positive valence, cognitive, social, arousal/regulatory).
Anxiety Disorders
| Disorder | Core Feature | Typical Onset |
|---|---|---|
| Generalized anxiety disorder (GAD) | Excessive worry across multiple domains ≥6 months, restlessness, fatigue, sleep disturbance | Gradual, adulthood |
| Panic disorder | Recurrent unexpected panic attacks, persistent worry about future attacks | Late adolescence/early adulthood |
| Specific phobia | Marked fear of specific object/situation, immediate response, avoidance | Childhood |
| Social anxiety disorder | Fear of social/performance situations involving scrutiny | Early adolescence |
| Agoraphobia | Fear of places where escape is difficult | Variable |
Physical symptoms—tachycardia, dyspnea, tremor—overlap with medical conditions, so PAs must rule out cardiac, endocrine (hyperthyroidism), and substance-induced causes.
Trauma- and Stressor-Related Disorders
Post-traumatic stress disorder (PTSD) follows exposure to actual/threatened death, serious injury, or sexual violence. Symptoms cluster into intrusion (flashbacks, nightmares), avoidance, negative alterations in cognition and mood, and hyperarousal (exaggerated startle, sleep disturbance), lasting >1 month.
Mood Disorders
Major depressive disorder (MDD) requires ≥5 symptoms during a 2-week period including depressed mood or anhedonia: sleep changes, weight/appetite change, psychomotor changes, fatigue, worthlessness/guilt, diminished concentration, recurrent thoughts of death.
Bipolar I disorder requires at least one manic episode (≥7 days of elevated/irritable mood, grandiosity, decreased need for sleep, pressured speech, risky behavior); major depressive episodes are common but not required for diagnosis. Bipolar II requires at least one hypomanic episode and one major depressive episode but no full mania.
Suicide risk assessment is a clinical priority: ask about ideation, plan, intent, means access, prior attempts, and protective factors.
Schizophrenia and Psychotic Disorders
Schizophrenia involves ≥2 of: delusions, hallucinations, disorganized speech, grossly disorganized or catatonic behavior, negative symptoms, with continuous signs ≥6 months and ≥1 month of active-phase symptoms.
| Symptom Domain | Examples |
|---|---|
| Positive | Hallucinations, delusions, thought disorder |
| Negative | Flat affect, anhedonia, avolition, alogia |
| Cognitive | Impaired working memory, executive dysfunction |
Dopamine dysregulation (mesolimbic hyperactivity, mesocortical hypoactivity) is the core neurotransmitter model; antipsychotics primarily block D2 receptors.
Personality Disorders
Personality disorders are enduring, inflexible patterns causing distress or impairment, stable from adolescence. DSM clusters:
| Cluster | Descriptor | Examples |
|---|---|---|
| A | Odd/eccentric | Paranoid, schizoid, schizotypal |
| B | Dramatic/emotional/erratic | Antisocial, borderline, histrionic, narcissistic |
| C | Anxious/fearful | Avoidant, dependent, obsessive-compulsive |
Borderline personality disorder is high-yield: unstable relationships, identity disturbance, impulsivity, self-harm, fear of abandonment, affective instability. Antisocial personality disorder requires conduct disorder before age 15.
Somatic and Dissociative Disorders
Somatic symptom disorder involves excessive thoughts/feelings/behaviors about somatic symptoms. Illness anxiety disorder features preoccupation with having a serious illness with minimal symptoms. Conversion disorder (functional neurological symptom disorder) presents neurological symptoms incompatible with recognized conditions.
Dissociative disorders include dissociative identity disorder (two or more distinct identity states with amnesia), dissociative amnesia, and depersonalization/derealization disorder.
Etiology: The Biopsychosocial Model
The diathesis-stress model integrates an underlying vulnerability (diathesis) with environmental stress to trigger disorder onset. Biopsychosocial etiology integrates:
- Biological — genetic heritability (twin concordance), neurochemistry, brain structure.
- Psychological — cognitive distortions, trauma history, coping style.
- Sociocultural — poverty, discrimination, social support, urbanicity.
This framework aligns with the PA-CAT Bulletin of Information, rev. 20240815 emphasis on integrated behavioral and clinical reasoning.
Worked Example — Differential Diagnosis
A 32-year-old presents with two weeks of low mood, anhedonia, fatigue, and insomnia after a job loss. The PA weighs:
| Condition | Key discriminator |
|---|---|
| Major depressive disorder (MDD) | ≥ 2 weeks of ≥ 5 symptoms causing impairment; no manic history |
| Adjustment disorder | Distress out of proportion within 3 months of a stressor; fewer than 5 symptoms |
| Bereavement / grief | Wave-like sadness with preserved positive affect; not persistent anhedonia |
| Bipolar depression | A prior manic or hypomanic episode changes treatment — avoid antidepressant monotherapy |
The two-week duration and five-symptom threshold distinguish MDD from adjustment disorder; screening for past mania (for example with the MDQ) is essential before prescribing, because an SSRI alone can precipitate a manic switch in bipolar I disorder.
Suicide Risk Assessment
Suicide risk assessment integrates ideation (passive versus active), intent, plan, access to means, prior attempts, substance use, and protective factors. The Columbia-Suicide Severity Rating Scale (C-SSRS) is a widely used structured tool. PA-CAT behavioral items test whether candidates escalate appropriately — active ideation with a plan and accessible means warrants emergency evaluation rather than routine outpatient follow-up.
A 24-year-old presents with 2 weeks of depressed mood, anhedonia, insomnia, fatigue, and recurrent thoughts of death. Symptoms impair function and are not attributable to substance use. The most likely diagnosis is:
A patient with a long-standing pattern of unstable relationships, impulsivity, fear of abandonment, and recurrent self-injury most likely has which personality disorder?