Biopsychology of Psychiatric Disorders

Overview of Psychiatric Disorders

  • Focus on the brain's role in psychiatric disorders.

Schizophrenia

  • Positive Symptoms
    • Excess of typical functions, e.g., incoherence, hallucinations, delusions.
  • Negative Symptoms
    • Absence of typical functions, e.g., flat affect, cognitive deficits, minimal speech.
  • Diagnosis
    • Requires the frequent recurrence of at least two symptoms for one month, including one positive symptom.
Antipsychotic Drugs for Schizophrenia
  • Chlorpromazine
    • Calms agitated schizophrenics and activates emotionally blunt patients.
  • Reserpine
    • Initially effective but withdrawn due to blood pressure effects.
  • Both drugs show Parkinson-like motor effects.
    • Suggests a connection to dopamine levels and schizophrenia.
Dopamine Theory of Schizophrenia
  • Connection established between decreased dopamine and Parkinson’s disease.
  • Antipsychotics act as dopamine antagonists:
    • Chlorpromazine: Binds and blocks dopamine receptors.
    • Reserpine: Depletes brain dopamine and other monoamines.
  • Consequences of increased dopamine:
    • Cocaine and amphetamines, being dopamine agonists, can induce schizophrenia-like psychosis.
  • Treatment effectiveness: Antipsychotics primarily address positive symptoms, less effective on negative symptoms.

Depressive Disorders

  • Normal Reaction vs. Major Depressive Disorder
    • Major depression persists, interferes with daily life, includes symptoms like despair, lack of energy, sleep issues, withdrawal, and anhedonia (loss of pleasure).
Antidepressant Medications
  • Major Classes:
    • Monoamine Oxidase Inhibitors (MAOIs): e.g., Iproniazid; prevents monoamine breakdown - must avoid tyramine-rich foods ("cheese effect").
    • Tricyclic Antidepressants: e.g., Imipramine; blocks reuptake of serotonin and norepinephrine, generally safer than MAOIs.
    • Selective Serotonin Reuptake Inhibitors (SSRIs): e.g., Prozac, Paxil, Zoloft; primarily target serotonin.
    • Selective Norepinephrine Reuptake Inhibitors (SNRIs): e.g., Reboxetine; block norepinephrine reuptake.
    • Atypical Antidepressants: e.g., Bupropion (blocks dopamine and norepinephrine); Agomelatine (melatonin receptor agonist).
    • NMDA-Receptor Antagonists: e.g., Ketamine, showing rapid antidepressant effects.

Bipolar Disorders

  • Types:
    • Bipolar Disorder Type I: experiences bouts of mania (or just manic episodes).
    • Bipolar Disorder Type II: involves depression and hypomania.
  • Symptoms of Hypomania: Reduced need for sleep, high energy, positive mood; mania can include delusions, overconfidence, impulsivity.
Mood Stabilizers for Bipolar Disorder
  • Types:
    • Lithium: a metallic ion, not classified as a typical drug; regulates mood without triggering mania.
    • Anticonvulsants: often used to stabilize mood.
    • Antipsychotics: serve as mood stabilizers.

Anxiety Disorders

  • Definitions:
    • Anxiety: Chronic fear in the absence of a threat, can lead to functional impairment.
    • Anxiety Disorder: Interferes with normal functioning; symptoms include fear, worry, and physiological effects like tachycardia, high blood pressure, sleep disturbances, etc.
  • Commonality: Most widespread psychiatric disorders.
Pharmacological Treatments for Anxiety Disorders
  • Benzodiazepines: e.g., Librium, Valium; widely prescribed, used for anxiety, sleep, and muscle relaxation. Side effects include sedation, ataxia, highly addictive with potential for withdrawal symptoms.
  • Role of Neurotransmitters: Anxiety treatments often target serotonin and GABA pathways.