Models of Abnormal behavior

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Models of Abnormal behavior

• Naomi Wagner, PhD

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Categories of Explanations of Abnormal Behavior

• Biological genetics, brain anatomy, biochemical
  imbalance, central nervous system, etc
• Psychological Emotions, thoughts. Personality,
  learning
• Social issues with relationships
• Sociocultural norms for behavior, expectations,
  cultural climate

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What is a Model?

• Etiology
• Cause or origin of a disorder
• Model
• An analogy used by scientists, usually to
  describe or explain a phenomenon or process they
  cannot directly observe
• Model, viewpoint, and perspective are often used
  interchangeably
• A multipath model considers interactions among
  all possible layers of causes
• Etiology
• Cause or origin of a disorder
• Model
• An analogy used by scientists, usually to
  describe or explain a phenomenon or process they
  cannot directly observe
• Model, viewpoint, and perspective are often used
  interchangeably

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Models (cont-d)

• These one-dimensional views are overly
  simplistic
• Set up a false either-or dichotomy between
  nature and nurture
• Fail to recognize the reciprocal influences of
  one on the other
• Mask the importance of acknowledging the
  contributions of all four dimensions in the
  origin of mental disorders

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The Biopsychosocial Model

• Interaction between the possible causes
• Multiple pathways to any disorder
• Not all causes contribute equally to a disorder
• People exposed to the same factors may not
  develop the same disorder
• People exposed to different factors may develop
  similar disorders

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The Structure of the nervous System
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The Structure of the Nervous system

• The Central Nervous System The brain and spinal
  cord
• The Peripheral Nervous System
• A. The Somatic NS
• B. The Autonomic NS (sympathetic and
  para-sympathetic.)

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Neural Transmission How is information
transmitted in the brain

• Neurons are separated by a gap (synapse)
• The neurons communicate at the synapse
• Neuron structure dendrite, cell-body, axon
• Electrical signals are transmitted chemically
  across the synapse
• The signals stimulate the pockets at the tip of
  the axon to release neurotransmitter

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Cont-d

• Electro- chemical transmission
• The signal stimulates the vesicles
• Vesicles release the neurotransmitter into the
  synapse
• Neurotransmitter Chemical substance released
  from a neuron into the synaptic cleft it drifts
  across the synapse and is absorbed by the
  receiving neuron
• The signal floats on the neurotransmitter to
  the next neuron
• Neurons form inter-connected pathways

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Cont-d

• The neurotransmitters can either excite or
  inhibit the neuron receiving the signal
• The activity of the neuron depends on the balance
  between on and off signals
• Serotonin is implicated in depression and the
  OCD.
• Dopamine is implicated in schizophrenia (too
  much) and Parkinson (too little)
• GABA (an inhibitory) is implicated in anxiety

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Biochemical Theories

• Basic premise
• Chemical imbalances underlie mental disorders
• Dendrites
• Receive signals from other neurons
• Axons
• Send signals to other neurons

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Neural Transmission
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Selected Neurotransmitters Involved in Some
Mental Disorders
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Abnormalities in Brain Structure

• It is not always possible to connect brain
  structures to psychological symptoms researchers
  believe that abnormally developed brain
  structures
• In 1848 an explosion during the paving of a rail
  road caused a metal rod to pierce Phineas Gage
  eye socket and to enter his brain
• As a result he showed significant changes in
  personality

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The Human Brain
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Functions of the brain

• The forebrain
• Controls all the higher mental functions, such as
  learning, speech, thought, and memory
• Thalamus
• Relay station transmits nerve impulses
  throughout brain
• Hypothalamus
• Regulates bodily drives and body conditions
• Limbic system
• Involves experiencing and expressing emotions and
  motivation

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Cont-d

• The midbrain
• Involved in vision and hearing, and along with
  the hindbrain, controls sleep, alertness, and
  pain
• Manufactures serotonin, norepinephrine, and
  dopamine
• The hindbrain
• Controls heart rate, sleep, and respiration
• Manufactures serotonin

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Genetic Influences

• Each cell of our body contains 46 chromosomes
• They are made of DNA our genetic material
• A gene is a segment of DNA along the length of
  the chromosome that contain the instructions for
  forming proteins which in turn determine how the
  cell works
• Proteins are the building blocks of our body

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Human Chromosomes
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Genetics (cont-d)

• Genetic abnormalities can come about through
• Inheritance of particular combinations of genes
• Faulty copying when cells reproduce
• Mutations that a person acquires over the course
  of life
• Cells possess the ability to repair many of the
  mutations
• The 46 chromosomes are arranged in 23 pairs
• One chromosome from mother and one from father

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Genetics (cont-d)

• Genetic makeup plays an important role in
  developing abnormal conditions
• Autonomic nervous system reactivity may be
  inherited
• Hereditary factors are implicated in alcoholism,
  schizophrenia, and depression

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What do genes do?

• Genes control the manufacturing of
  neurotransmitters as well as the way the
  neurotransmitters behave at the synapse
• Genes also determine how the brain structures
  develop throughout life
• Any factor that can alter the genetic code can
  alter how those structures perform

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Genotype and Phenotype

• The 46 chromosomes are arranged in 23 pairs
• Twenty-two of the pairs are identical (the 23rd
  pair is the sex chromosomes XX and XY )
• It means that the same gene is located in the
  same place on each of the chromosomes
• Two forms of the same gene are called alleles
• The Genotype is the overall genetic makeup
• The Phenotype is the expression in your physique
  and psychological attributes

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Dominant Recessive Relationship

• The Alleles are related to each other in
  Dominant- Recessive relationship
• a dominant allele prevails over a recessive
  allele
• However, human characteristic and psychological
  disorders are polygenic- more than one gene
  participates in determining a given
  characteristic
• Epigenetics is the attempt to understand how the
  environment affects genes to produce genotypes

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PATTERN OF DOMINANT-RECESSIVE TRAIT INHERITANCE
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Genes-environment Interactions

• Interactions between genes and the environment
• Passive exposure Children are exposed to
  environments that their parents create based on
  the parents genetic predisposition
• The childs genetically- based traits elicits
  responses from the environment
• Niche-Picking the child seeks out an environment
  that gratifies his/her genetically- based
  inclinations

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Diathesis-Stress Model

• Proposal that people are born with a
  predisposition that places them at risk for
  developing a psychological disorder if exposed to
  certain extremely stressful life experiences.

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Assessment of Genetic Factors

• Family inheritance studies Researchers compare
  the disorder rates across relatives who have
  varying degrees of genetic relatedness
• Usually comparing Identical twins who share 100
  of their genes to Fraternal twins who share 50
  of their genes
• Studies comparing parents and children are
  confounded because of possible environmental
  effect

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Biologically- Based Therapies

• Psychopharmacology
• Study of effect of drugs on mind and behavior
• Electroconvulsive therapy
• Application of electric voltage to the brain to
  induce convulsions
• Psychosurgery
• Brain surgery for the purpose of correcting a
  severe mental disorder