chapter 7

• Substance use disorder


  Misuse, abuse, dependence

  
• Drug dependence


  Need to maintain certain level of drug in the bloodstream to avoid withdrawal symptoms
• Drug tolerance


  Consuming increasing amounts of a drug to experience desired effect
• Drug dependence

  • Can be physical and/or psychological
  • Physical: need to maintain certain level of drug in the bloodstream to avoid withdrawal symptoms
  • Psychological: craving for the feeling a drug produces
• Drug tolerance


  • Metabolic (Pharmacokinetic): repeated exposure accelerates the rate at which the drug is decomposed by the liver
  • Pharmacodynamic: repeated exposure leads to cellular adaptation
• Causes of substance use disorders


  • Biological factors
  • Psychological
  • Interpersonal
  • Environmental
• Substance misuse


  Use that results in adverse consequences that are not recurrent
• Substance abuse


  Maladaptive pattern of use that manifests recurrently and has significant consequences
• Substance dependence


  Cluster of cognitive, behavioural and physiological symptoms that indicate that a person compulsively continues to use a substance
• Substance use behaviour occurs on a continuum

  
• Substance dependence can be understood as addiction
• Different degrees of severity require different types of interventions
• Biological factors


  • Inherited vulnerability
• Psychological factors


  • High levels of novelty seeking and sensation seeking
  • High levels of disinhibition (low behaviour control and high impulsivity)
  • Deficits in psychosocial skills; depression and anxiety disorders
• Interpersonal factors


  • Family dysfunction (e.g. marital discord, criminal behaviour)
  • Inadequate and inconsistent family management practices
  • Normalisation of substance use
  • Drug-using peers
  • Peer pressure
• Environmental factors

  • Dropping out of school, low levels of educational achievement
  • Exposure to substance use/abuse
  • Degree of acceptance or approval in community
  • Availability of drugs in community
  • Occupational factors, such as the dop system in farming/viticulture
• Research: there appears to be significantly greater heritability for substance dependence > substance abuse > non-problematic use

  
• Neurological processes that contribute to substance dependence


  1. Reinforcement (Rewarding stimulus or relief from an unpleasant sensation (positive reinforcement))

  2. Neuro-adaptation (Compensatory adjustment of the brain)
• Nervous system


  Made up of over 100 billion cells called neurons
• Nervous system


  • Responsible for collecting information from the environment, sending this information to the right places in the body and then enabling the body to respond to this information
• Central nervous system


  Made up of the spinal cord and the brain
• Spinal cord


  Found in the spinal column that runs down the middle of the back, communicates with all the muscles and sense organs of the body below the head
• Spinal cord


  • Has grey matter (inner part) surrounded by white matter (outer part), pairs of spinal nerves attached at 31 points
• Medulla oblongata


  Start of the brain at the top of the spinal cord
• Brain


  About the size of a large grapefruit, looks like a wrinkly walnut, consistency of porridge, protected by cerebrospinal fluid, meninges, and the skull
• Describing the brain


  1. By looking at the regions in order of evolutionary development (hindbrain, midbrain, forebrain)

  2. By looking at the hemispheres
• Hindbrain


  Earliest part of the brain, responsible for survival functions
• Hindbrain


  • Medulla oblongata (controls breathing, circulation, heart, involuntary behaviours)
  • Pons (relay station, role in sleeping and waking)
  • Cerebellum (coordinates movement, balance, posture)
• Midbrain


  Includes the reticular formation (responsible for arousal and sleep/wake consciousness)
• Forebrain


  Developed later, involved in complex cognitive functions, sensory processes and emotions
• Structures of the forebrain


  • Thalamus (processes incoming sensory information)
  • Hypothalamus
  • Limbic system
  • Basal ganglia
  • Cerebrum (cortex)
• Neuropsychology


  Links knowledge from neurology and psychology, studies the relationship between the mind and the brain
• Divisions of neuropsychology


  • Research neuropsychology (how mental functions are organised in the brain)
  • Clinical neuropsychology (diagnosis and management of mental aspects of neurological disease)
• When you wrote an examination, you would need more arousal to watch television
• If the reticular formation is damaged, a permanent state of sleep or coma can result
• Forebrain


  The last area of the brain to develop in the course of evolution, involved in complex cognitive functions, sensory processes and emotions
• Structures that make up the forebrain


  • Thalamus
  • Hypothalamus
  • Limbic system
  • Basal ganglia
  • Cerebrum
• Thalamus


  The first structure to process incoming sensory information before relaying it to the appropriate area of the brain for further processing
• Hypothalamus


  A very small structure involved in many different activities, controls the pituitary gland, involved in emotions, regulating body rhythms for sleep, sexual activity, temperature regulation, hunger and thirst
• Limbic system


  Involved in emotion, memory, learning and motivation, most important parts are the amygdala and the hippocampus