Neuropsychiatric Illness and Major Psychiatric Disorders

Neuropsychiatric Illness

Disorders of Emotion

Major Psychiatric Disorders

Schizophrenia

Definition

  • A serious mental disorder characterized by disordered thoughts, delusions, hallucinations, and other bizarre behaviors.

Prevalence

  • Affects approximately 1% of the population.

  • In the USA, there are enough individuals with schizophrenia to populate a city the size of Greater San Diego.

Nature of the Disorder

  • It is a lifelong disorder with no known cure.

Diagnostic Criteria

  • Six diagnostic criteria must be met, which include:

    • Critical symptoms can be divided into cognitive and emotional dimensions.

    • Cognitive:

      • Delusions

      • Hallucinations

      • Incoherence in language (thought disorder)

    • Emotional:

      • Blunted/flat affect

    • Evidence of deterioration in functioning.

    • Symptoms present for at least 6 months.

    • If affective disorder is present, it must be secondary to the schizophrenia.

    • Onset before age 45.

    • Symptoms must not be due to known organic brain disorders (e.g., toxic effects or dementia).

Core Symptoms of Schizophrenia

Positive Symptoms

  • Three Core Positive Symptoms:

    1. Hallucinations

    2. Delusions

    3. Thought disorder

Negative Symptoms

  • Four Core Negative Symptoms:

    1. Flat affect

    2. Lack of speech

    3. Anhedonia (inability to experience pleasure)

    4. Social withdrawal

What Causes Schizophrenia?

  • Dopamine Hypothesis:

    • Overactive dopamine system implicated.

    • Too many dopamine receptors.

    • Excess dopamine release.

  • Neuromodulator Functions:

    • Involved in movement, reward, cognitive functions (short-term memory, attention).

Evidence Supporting the Dopamine Hypothesis

  • Neuroleptics (e.g., Haldol) effectively treat positive symptoms by blocking dopamine receptors.

  • Dopamine agonists (e.g., amphetamine) can exacerbate symptoms and mimic schizophrenia when administered in high doses (amphetamine psychosis).

Limitations of the Dopamine Hypothesis

  • Dopamine functions in multiple brain areas:

    • Motor system involved in voluntary movement—schizophrenics do not exhibit movement problems.

    • Parkinson's patients, who have low dopamine levels, do not exhibit psychosis.

Dopamine Pathways in the Brain

  • Dopaminergic diffuse modulatory systems:

    • The mesocortico-limbic dopamine system arises in the ventral tegmental area, implicated in schizophrenia.

    • Another system arises from the substantia nigra, controlling voluntary movement via the striatum.

Neuroleptics and Side Effects

  • Neuroleptics affect both dopamine systems, which may lead to side effects such as:

    • Tardive Dyskinesia: Movement disorder associated with excessive dopamine receptor activity, presenting as repetitive muscle movements in various body parts.

Modern Anti-Schizophrenic Medications

  • Clozapine:

    • An atypical antipsychotic that does not strongly target D2 receptors (associated with the movement system).

    • Works more on D3 and D4 receptors prevalent in the limbic system and frontal lobes.

Causes of Negative Symptoms

  1. Neurological damage.

  2. Possibly involves glutamate receptors (glutamate is the most prominent fast-acting neurotransmitter in the cortex).

    • Glutamate hypothesis implicates NMDA receptor hypofunction, leading to negative symptoms due to an underactive glutamate system.

Genetic and Environmental Factors in Schizophrenia

  • Genetic Hypothesis:

    • Heritability indicated, with a notable lifetime risk when first-degree relatives are affected (approximately 10-20%).

    • Rates differ significantly between identical (monozygotic) and fraternal (dizygotic) twins.

  • Environmental Hypothesis:

    • Diathesis-stress model explains that an underlying genetic vulnerability is activated by environmental stressors (e.g. trauma).

Depression/Mood Disorders

Types of Major Depression

  1. Reactive (Non-Clinical) Depression:

    • Normal responses to life events, typically transient (short-term).

  2. Major Depressive Disorder (MDD):

    • Pervasive low mood affecting all life aspects.

    • Symptoms last from 2 to 6 months and cycle, with episodes averaging 13 months.

    • More prevalent in females (2-3 times more) and has a lifetime risk between 7-20%.

Symptoms of MDD

  • Typical symptoms include:

    • Low mood.

    • Anhedonia (loss of interest in activities once enjoyed).

    • Rumination and feelings of worthlessness.

    • Inappropriate guilt or regret.

    • Helplessness or hopelessness.

    • Other symptoms include:

    • Poor concentration.

    • Social withdrawal.

    • Reduced sex drive.

    • Irritability.

    • Thoughts of death or suicide.

    • Insomnia or hypersomnia.

Causes of Depression

  • Approximately 40% of the risk is genetic, with numerous genetic variants linked to MDD identified through genome-wide association studies.

  • The diathesis-stress model suggests that preexisting vulnerabilities may be triggered by environmental stress.

Bipolar Disorder - Manic/Depression

  • Characterized by alternating periods of despondency and elation, affecting males and females equally.

  • Average age of onset is 30.

  • Patterns of depression typically last 6 months; mania lasts about 2 months.

Types of Bipolar Disorders

  • Type 1: Cycling between mania and depression.

  • Type 2: Cycling between depression and hypomania, with less extreme mood elevations.

  • Cyclothymia: Fluctuations between hypomania and mild depression.

Brain Areas in Bipolar Disorder

  • Proposed reduced responsiveness in cognitive control areas (DMPFC, VLPFC).

  • Proposed increased responsiveness in emotional regulation areas (amygdala).

Causes of Bipolar Disorder

  • Family history significantly influences risk (10x greater if a close relative has it).

  • Concordance rates in studies demonstrate a high likelihood in identical twins (70%) versus fraternal twins (20%).

Anxiety Disorders

Four Primary Types of Anxiety Disorders:

  1. Generalized Anxiety Disorder (GAD)

  2. Panic Disorder

  3. Phobias

  4. Post-traumatic Stress Disorder (PTSD)

  5. Obsessive-Compulsive Disorder (OCD)

Generalized Anxiety Disorder (GAD)

  • Characterized by excessive, ongoing worry without realistic views of problems, including restlessness, irritability, and muscle tension.

Panic Disorder

  • Involves periodic feelings of extreme fear or terror, with symptoms including heart palpitations, dizziness, and may involve agoraphobia.

  • Characterized by an onset before age 35, and 2% incidence rate equally affecting men and women.

Treatment Approaches for Anxiety Disorders

  • Behavioral therapies (such as systematic desensitization).

  • Pharmacological treatments include benzodiazepines that act as GABA agonists.

PTSDt

  • Defined by recurrent dreams or recollections of a traumatic event, often leading to avoidance behaviors and social withdrawal, as well as heightened sensory responsiveness (e.g., startle reflex).

Treatment Approaches for PTSD

  • Focus on addressing the traumatic event and associated symptoms through therapeutic modalities.

Obsessive-Compulsive Disorder (OCD)

  • Characterized by obsessions (persistent thoughts) and compulsions (repetitive behaviors). Incidence is about 1-2%, slightly more common in females.

  • Serotonin: Treatment primarily uses SSRIs, which block compulsive behaviors originating in the frontal lobes.

Overall, these notes cover key aspects of neuropsychiatric illness, major psychiatric disorders, and their characteristics, symptoms, underlying factors, and treatment modalities.