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PsychiatricStra Disorders

| Part 13 – Neurologic Disorders

KEY CLINICAL POINTS

  • Psychiatric disorders encompass a wide range of conditions including anxiety, mood disorders, schizophrenia, and eating disorders, with significant global prevalence and impact on public health.
  • Anxiety disorders (e.g., panic disorder, generalized anxiety disorder) are characterized by excessive fear or worry, with treatment options including SSRIs, SNRIs, and benzodiazepines.
  • Mood disorders like bipolar disorder and major depressive disorder require careful differentiation, with lithium, anticonvulsants, and atypical antipsychotics as key treatment modalities.
  • Schizophrenia is managed with antipsychotic medications (first- and second-generation), with clozapine being effective for treatment-resistant cases but requiring monitoring for agranulocytosis.
  • Eating disorders (e.g., anorexia nervosa, bulimia nervosa) involve significant physical and psychological impairment, often requiring multidisciplinary approaches including psychotherapy and nutritional support.

DEFINITION & OVERVIEW

Psychiatric disorders are mental health conditions characterized by disturbances in thought, mood, behavior, or perception. They include anxiety disorders, mood disorders (e.g., depression, bipolar disorder), schizophrenia, and eating disorders. These conditions significantly impact quality of life and require comprehensive management.

EPIDEMIOLOGY

Psychiatric disorders are prevalent globally, with major depressive disorder affecting ~15% of adults and bipolar disorder affecting ~1-1.5%. Schizophrenia has a lifetime prevalence of ~0.85%, with 300,000 annual episodes in the U.S. Anxiety disorders affect ~18% of adults, while eating disorders have a 1-2% prevalence in women. Socioeconomic and cultural factors influence incidence and outcomes.

ETIOLOGY & PATHOPHYSIOLOGY

Genetic, neurobiological, and environmental factors contribute to psychiatric disorders. Neurotransmitter imbalances (e.g., serotonin, dopamine), brain structure abnormalities, and psychosocial stressors play roles. For example, schizophrenia involves dopamine dysregulation and genetic predisposition, while mood disorders may involve circadian rhythm disruptions and inflammatory processes.

CLINICAL MANIFESTATIONS

Symptoms vary by disorder: anxiety disorders present with excessive worry or panic attacks; mood disorders involve persistent sadness or manic episodes; schizophrenia includes delusions, hallucinations, and disorganized thinking; eating disorders feature restrictive eating, binge-purge cycles, or weight loss. Physical symptoms (e.g., fatigue, weight changes) and functional impairments are common.

DIAGNOSTIC CRITERIA

Diagnosis follows DSM-5-TR criteria. For example, major depressive disorder requires at least two of the following: depressed mood, anhedonia, weight change, sleep disturbances, psychomotor changes, fatigue, guilt, or suicidal ideation for ≥ 2 weeks. Bipolar disorder requires manic or hypomanic episodes with depressive episodes. Schizophrenia requires two or more symptoms (e.g., delusions, hallucinations, disorganized speech) for ≥ 6 months.

TREATMENT & MANAGEMENT

Treatment is multimodal, combining pharmacotherapy, psychotherapy, and lifestyle interventions. Antidepressants (SSRIs, SNRIs), mood stabilizers (lithium, valproate), and antipsychotics (clozapine, risperidone) are used. Cognitive-behavioral therapy (CBT), dialectical behavior therapy (DBT), and family therapy are effective. For schizophrenia, long-acting injectables (LAI) improve adherence. Eating disorders require nutritional counseling and psychotherapy.

SPECIAL CONSIDERATIONS

Special populations require tailored approaches: pregnancy necessitates safer medications (e.g., SSRIs for depression), while elderly patients may need lower doses to avoid side effects. Comorbid conditions (e.g., substance use, medical illnesses) complicate management. Cultural factors and socioeconomic status influence treatment access and outcomes.

TREATMENT ALGORITHMS

For depression: Start with SSRIs (e.g., fluoxetine, sertraline). If ineffective, add SNRIs or atypical antipsychotics. For bipolar disorder: Lithium or valproate for acute mania; mood stabilizers with antipsychotics for maintenance. Schizophrenia: First-line antipsychotics (e.g., risperidone, olanzapine); clozapine for treatment-resistant cases. Eating disorders: Nutritional support + CBT or family-based therapy.

TABLES & DIAGNOSTIC TOOLS

Key tables include: 1) Antidepressants (Table 463-1), 2) Antipsychotics (Table 463-10), 3) Diagnostic criteria for Bipolar I Disorder (Table 463-8), 4) Mood stabilizers (Table 463-9). These tools guide medication selection and differential diagnosis.