BIOPSYCHOLOGY OF PSYCHIATRIC DISORDERS

Psychiatric disorders

are complex disorders involving behavior, cognition, emotion, and biological processes.

Schizophrenia

is a psychiatric disorder characterized by significant disturbances in thought, perception, behavior, and emotional functioning.

Positive symptoms

The presence of abnormal experiences or behaviors.

Examples include:

- Hallucinations

- Delusions

- Disorganized behavior

- Disturbed thought processes

Negative symptoms

involve reductions or losses of normal psychological functions.

Examples include:

- Reduced emotional expression

- Reduced speech

- Social withdrawal

- Reduced motivation

dopamine theory of schizophrenia

proposes that abnormal dopamine activity contributes to the disorder.

Antipsychotic Drugs

The discovery that certain drugs could reduce schizophrenic symptoms contributed to the dopamine hypothesis.

Important drugs discussed include:

- Chlorpromazine

- Haloperidol

- Clozapine

Many ____ drugs influence dopamine D2 receptors.

Important limitations include:

- Antipsychotic drugs do not eliminate all symptoms.

- Positive and negative symptoms may respond differently.

- The actions of antipsychotic drugs do not necessarily identify the original cause of schizophrenia.

- Other neurotransmitter systems and brain abnormalities are involved.

- Thus, schizophrenia cannot be adequately understood through dopamine alone.

Affective disorders

also called mood disorders, are psychiatric disorders characterized primarily by disturbances of mood or emotion.

Clinical depression or major depressive disorder

is characterized by persistent depressive symptoms and associated changes in functioning.

Mania

is characterized by:

- Excessive energy

- Overconfidence

- Impulsivity

- Distractibility

- Increased activity

- Grandiosity

Unipolar Affective Disorder

Depressive episodes occur without episodes of mania.

Reactive depression

- associated with an identifiable negative experience.

Endogenous depression

- depression without an apparent external cause.

Seasonal affective disorder (SAD)

- depressive episodes that recur seasonally, typically during winter.

Postpartum depression

- depression occurring after childbirth.

Brain Pathology

Two structures repeatedly implicated in affective disorders are:

- Amygdala

- Anterior cingulate cortex

Research has reported structural and functional abnormalities involving these regions, although

findings are not completely consistent across studies.

Monoamine Theory/Monoamine theory of depression

proposes that depression is associated with reduced activity at:

- Serotonergic synapses

- Noradrenergic synapses

This theory was influenced by

diathesis-stress model

proposes an interaction:

- Diathesis - an inherited susceptibility

- Stress - environmental or experiential challenges

A susceptibility alone may not be sufficient to produce depression. Stress may contribute to the

development or expression of the disorder in susceptible individuals.

Monoamine oxidase inhibitors (MAO inhibitors)

increase the availability of monoamine neurotransmitters by inhibiting their breakdown.

Tricyclic antidepressants

such as imipramine, affect monoamine neurotransmission

and were important early antidepressant treatments.

Selective serotonin-reuptake inhibitors (SSRIs)

block the reuptake of serotonin,

increasing serotonin's effects at the synapse.

Fluoxetine (Prozac)

was the first widely developed SSRI discussed in the chapter.

Mood stabilizers

particularly lithium, are used in the treatment of bipolar affective

disorder.

Anxiety

- is described as chronic fear that persists in the absence of a direct threat.

- can be adaptive when it motivates effective coping.

- It becomes an anxiety disorder when it becomes sufficiently severe to disrupt normal functioning.

- has both genetic and experiential components.

may involve:

- Fear and worry

- Increased heart rate

- Increased blood pressure

- Nausea

- Breathing difficulties

- Sleep disturbances

- Elevated glucocorticoid levels

Generalized Anxiety Disorder

Persistent and excessive anxiety that is not limited to one particular situation.

Phobic Anxiety Disorders

Excessive fear associated with particular objects or situations.

Agoraphobia

Fear associated with situations from which escape may be difficult or embarrassing.

Panic Disorder

Characterized by recurrent episodes of intense anxiety or panic.

Obsessive-Compulsive Disorder

Characterized by intrusive thoughts and repetitive behaviors or mental acts.

Posttraumatic Stress Disorder

A disorder associated with persistent psychological and physiological responses following traumatic experiences.

Amygdala

Anterior cingulate cortex

Two structures particularly relevant to anxiety are:

Benzodiazepines

act primarily through GABA-related mechanisms but can produce sedation, motor impairment, withdrawal reactions, and dependence.

Buspirone

produces anxiolytic effects through serotonin-related mechanisms and does not produce the same degree of sedation and motor effects associated with benzodiazepines.

comorbidity

meaning they frequently occur in the same individual.

Tourette Syndrome

- is characterized by tics.

- are commonly treated with neuroleptics, particularly D2 receptor blockers.

- The response of tics to D2 receptor blockers is consistent with involvement of dopaminergic

activity within basal-ganglia circuits.

Tics

- Involuntary

- Repetitive

- Stereotyped

They may involve:

- Movements

- Vocalizations

Echolalia

The repetition of another person's words.

Neural Basis

Research has particularly implicated the:

- Caudate nuclei

- Basal ganglia

- Thalamus

- Cort-ex

- Sensorimotor cortex

Translational research

- refers to research intended to transform basic scientific discoveries into effective clinical applications.

In psychiatric research, the process involves moving from:

basic biological findings → potential treatment → controlled clinical evaluation

- The important concept is that promising findings in basic research do not automatically become

effective clinical treatments.

Clinical trials

- systematically evaluate potential treatments in human participants.

Important methodological issues include:

- Appropriate comparison groups

- Placebo effects

- Blinding

- Treatment efficacy

- Side effects

- Long-term outcomes

active placebo

- produces noticeable effects similar to those of the treatment being tested

without containing the treatment's presumed therapeutic mechanism.

- This can help control for the possibility that participants identify their treatment condition from

its subjective effects.

translational bottleneck

refers to the difficulty of successfully moving discoveries from basic research into effective clinical treatments.

Chlorpromazine

Haloperidol

Clozapine

(3) Important Antipsychotic Drugs discussed include:

Reactive depression

Endogenous depression

Seasonal affective disorder (SAD)

Postpartum depression

4 several forms of depression:

Monoamine oxidase inhibitors (MAO inhibitors)

Tricyclic antidepressants

Selective serotonin-reuptake inhibitors (SSRIs)

Fluoxetine (Prozac)

Mood stabilizers

(5) Pharmacological Treatment of Affective Disorders

Generalized Anxiety Disorder

Phobic Anxiety Disorders

Agoraphobia

Panic Disorder

Obsessive-Compulsive Disorder

Posttraumatic Stress Disorder

6 Major Classes Discussed

Benzodiazepines

Serotonin agonists

Antidepressants

(3) major categories discussed are: