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Neuroscience: Exploring the Brain, 3e

Neuroscience: Exploring the Brain, 3e. Chapter 22: Mental Illness. 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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Neuroscience: Exploring the Brain, 3e

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  1. Neuroscience: Exploring the Brain, 3e Chapter 22: Mental Illness

  2. 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

  3. 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

  4. Anxiety Disorders • Fear • An adaptive response to threatening situations • Innate and species-specific • Learned • Anxiety disorders • Characterized by inappropriate expression of fear

  5. Anxiety Disorders • Common Anxiety Disorders • Panic disorder • Agoraphobia • Obsessive-compulsive disorder • Generalized anxiety disorder • Specific phobias • Social phobia • Post-traumatic stress disorder

  6. 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

  7. Anxiety Disorders • Biological Bases of Anxiety Disorders (cont’d) • Stress Response Cortisol release & sympathetic activation

  8. 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

  9. Stress response: negative feedback via hippocampus Hippocampus Negative feedback Amygdala Stress Glucocorticoid (Cortisol) release Adrenal glands Hypothalmic CRF release Pituitary, ACTH

  10. Anxiety Disorders • Treatments for Anxiety Disorders • Psychotherapy • Anxiolytic Medications • Role of GABA • Benzodiazepines • Serotonin-selective reuptake inhibitors (SSRIs) • Drug target: CRH receptors (at hypothalamus)

  11. 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)

  12. 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

  13. 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

  14. Epigenetic imprinting: Stress response Maternal care: Licking & grooming pups Adult ‘memory’ of maternal care 5HT release Hippocampus Negative feedback Chromatin remodeling cAMP, PKA (DeMethylation of NGFi binding site) NGFi transcript. factor Long-term up regulation of GC mRNA expression Glucocorticoid receptors Stress Adrenal glands Hypothalmic CRF release Pituitary, ACTH Glucocort. release

  15. 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

  16. Anxiety Disorders • Treatments for Affective Disorders (cont’d) • Antidepressants

  17. Anxiety Disorders • Treatments for Affective Disorders • Lithium

  18. 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

  19. 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

  20. 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

  21. 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

  22. 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

  23. End of Presentation

  24. Mental Illness and the Brain • Human behavior • Product of brain activity • Brain • Product of two mutually interacting factors • DNA • Determines individualism

  25. 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

  26. 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

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