Neuroscience: Exploring the
Brain, 3e
Chapter 22: Mental Illness
Copyright © 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins
Mental Illness and the Brain
• Mental illness
– Diagnosable disorder of thought, mood, or behavior
that causes distress or impaired functioning
– Earlier belief
• Disorders of the body
• Disorders of the mind
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Mental Illness and the Brain
• Biological Approaches to Mental Illness
– Infection-related disease e.g., ‘general paresis of the
insane’
• Symptoms: Mania, cognitive deterioration
• Cause: T. pallidum infection
– Penicillin (1928)
– Mental illnesses traced directly to biological causes
– Roots of mental disorders
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Anxiety Disorders
• Fear
– An adaptive response to threatening situations
– Innate and species-specific
– Learned
• Anxiety disorders
– Characterized by inappropriate expression of fear
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Anxiety Disorders
• Common Anxiety Disorders
– Panic disorder
– Agoraphobia
– Obsessive-compulsive disorder
– Generalized anxiety disorder
– Specific phobias
– Social phobia
– Post-traumatic stress disorder
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Anxiety Disorders
• Biological Bases of Anxiety Disorders
– Fear evoked by threatening stimulus: Stressor
– Manifested by stress response
– Stimulus-response relationship strengthened (and
weakened) by experience
– Stress: Corticotropin-releasing hormone (CRH)
adrenocorticotropic hormone (ACTH) cortisol
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Anxiety Disorders
• Biological Bases of Anxiety
Disorders (cont’d)
– Stress Response
Cortisol release &
sympathetic activation
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Anxiety Disorders
Regulation of the HPA Axis by the Amygdala and Hippocampus
– Both regulate CRH neurons
• Amygdala projects to bed nucleus of the stria
terminalis, which activates the HPA axis
• Hippocampus deactivates the HPA axis
• Glucocorticoid receptors
• Feedback loop
– Push-pull style regulation
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Stress response: negative feedback via hippocampus
Hippocampus
Negative feedback
Amygdala
Stress
Glucocorticoid
(Cortisol) release
Hypothalmic
CRF release
Adrenal glands
Pituitary, ACTH
9
Anxiety Disorders
• Treatments for Anxiety Disorders
– Psychotherapy
– Anxiolytic Medications
– Role of GABA
– Benzodiazepines
– Serotonin-selective reuptake inhibitors (SSRIs)
– Drug target: CRH receptors (at hypothalamus)
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Anxiety Disorders
• A Description of Affective Disorders
– “Mood” Disorders
–
Depression
• Major Depression
• Dysthymia (less severe)
– Bipolar Disorder
• Manic-depressive disorder
• Mania (type I) or hypomania (type II)
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Anxiety Disorders
• Biological Bases of Affective Disorders
– The Monoamine Hypothesis
• Problems with diffuse modulatory systems
• Reserpine (depletes MAs)
• Monoamine Oxidase (MAO)
• Imipramine (reuptake inhib)
• Monoamine hypothesis of mood disorders
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Anxiety Disorders
• Biological Bases of Affective Disorders (cont’d)
– The Diathesis-Stress Hypothesis
• Genetic and nongenetic
• Diathesis (predispositions)
• HPA system- Convergence site; genetic and environ.
• Impact of CRH on HPA function
 Role of early experience in shaping stress
response
Glucocorticoid receptors and influence of
Tactile stimulation in rats
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Epigenetic imprinting: Stress response
Maternal care:
Licking & grooming
pups
5HT release
Adult ‘memory’ of
maternal care
Hippocampus
Negative feedback
cAMP, PKA
NGFi transcript.
factor
Glucocorticoid
receptors
Chromatin
remodeling
(DeMethylation of
NGFi binding site)
Long-term up
regulation of GC
mRNA expression
Stress
Hypothalmic
CRF release
Adrenal glands
Pituitary, ACTH
Glucocort. release
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Anxiety Disorders
• Treatments for Affective Disorders
– Electroconvulsive Therapy (ECT): Localized electrical
stimulation
– Advantage of ECT: Quick relief
– Adverse effect of ECT: Prior memories, storage of
new information
– Structures involved: Temporal lobe
– Psychotherapy: Help patients overcome negative
views
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Anxiety Disorders
• Treatments for Affective Disorders (cont’d)
– Antidepressants
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Anxiety Disorders
• Treatments for Affective Disorders
– Lithium
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Schizophrenia
• A Description of Schizophrenia
– Severe mental disorder
– Symptoms of schizophrenia: Loss of contact with
reality
– Three types of schizophrenia
• Paranoid schizophrenia
• Disorganized schizophrenia
• Catatonic schizophrenia
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Schizophrenia
• Biological Bases of Schizophrenia
– Genes and the Environment
• Schizophrenia: genetic predispositions
• Schizophrenia and the ventricle to-brain-size ratio
• Other structural observation of the brains of
schizophrenics
– The Dopamine Hypothesis: Psychotic episodes in
schizophrenia triggered by activation of dopamine
receptors
– Neuroleptic drugs
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Schizophrenia
• Biological Bases of Schizophrenia (cont’d)
– The Glutamate Hypothesis
• Behavioral effects of phencyclidine (PCP)
• Introduced in1950s as an anesthetic
• Inhibits NMDA receptors
– Glutamate: Fast excitatory neurotransmitter in the
brain, two important receptor subtypes, AMPA and
NMDA
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Schizophrenia
• Treatments for Schizophrenia
– Consists of drug therapy combined with psychosocial
support
– Conventional neuroleptics, such as chlorpromazine
and haloperidol, act at D2 receptors
• Reduce the positive symptoms of schizophrenia
• Also have numerous side effects
– NMDA receptor
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Concluding Remarks
• Impact of neuroscience on psychiatry
• Causes of mental illness still unclear, despite knowing
how chemical synaptic transmission is affected by drugs
• Genes and environment play an important role
• Environmental stresses may contribute to schizophrenia
• Appropriate sensory stimulation in early childhood
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End of Presentation
Copyright © 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins
Mental Illness and the Brain
• Human behavior
– Product of brain activity
• Brain
– Product of two mutually interacting factors
• DNA
– Determines individualism
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Mental Illness and the Brain
• Psychosocial Approaches to Mental Illness
– Freud’s theory: Mental illness- Unconscious and
conscious elements of psyche come into conflict
– Skinner: Many behaviors are learned
responses to the environment
– Maladaptive behavior
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Introduction
• Neurology
–
Branch of medicine concerned with the diagnosis and treatment
of nervous system disorders
• Neurological disorders
–
Help illustrate the role of physiological processes in normal brain
function
• Psychiatry
–
Branch of medicine concerned with the diagnosis and treatment
of disorders that affect the mind or psyche
• Psychiatric disorders
–
Examples: Anxiety disorders, affective disorders, schizophrenia
Copyright © 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins