Potential Drug Abuse

• Drug abuse


  Using a drug in a fashion inconsistent with medical or social norms
• Drug abuse is culturally defined, so what is considered drug abuse may differ in individual cultures
• Examples of cultural differences in defining drug abuse

  • In the United States, moderate consumption of alcohol is not usually considered abuse
  • In some Muslim societies, any ingestion of alcohol may be considered abuse
• Cultural definitions of abuse can change over time
• Example of changing cultural definitions of drug abuse


  • When psychedelic use first became popular in America, these agents were legal and their use was not generally disapproved
  • When use of psychedelics became widespread, our societal posture changed and legislation was passed to make the manufacture, sale, and use of these drugs illegal
• Drug addiction


  A chronic relapsing brain disease that is characterized by compulsive drug seeking use, despite the harmful consequences
• Addiction is a very complex phenomenon that includes social, psychological, genetic, and environmental components
• Physical dependence is neither necessary nor sufficient for addiction to occur
• Tolerance


  A state where a particular dose elicits smaller response than it did with the initial dose and as tolerance increases higher and higher doses are needed to elicit desired effects
• Cross tolerance


  A state in which tolerance to one drug confers tolerance to another and cross tolerance generally develops among drugs within a particular class and not between drugs in different classes
• Psychological dependence


  An intense subjective need for a particular psychoactive drug
• Physical dependence


  A state in which abstinence syndrome will occur if the drug is discontinued and physical dependence is the result of a neuro adaptive process that takes place in response to prolonged drug exposure
• Cross dependence


  The ability of a drug to support physical dependence on another drug
• Withdrawal syndrome


  A constellation of signs and symptoms that occurs in physically dependent individuals when they discontinue drug use
• Substance abuse disorder


  Continued use of a substance despite significant substance-related problems and a change in brain circuitry that persists despite detoxification
• Diagnosis of a substance abuse disorder is based on behaviors related to continued use of a substance
• Factors that contribute to drug abuse

  • Reinforcing properties of drugs
  • Physical dependence
  • Psychological dependence
  • Social factors
  • Drug availability
  • Vulnerability in the individual
• Neurobiology of addiction


  • Voluntary users can become compulsive users as a result of molecular changes in the brain
  • The reward circuit normally serves to reinforce behaviors essential for survival
  • The major transmitter is dopamine and addictive drugs cause the release of dopamine
  • Activating that reward circuit encourages the repetition of the behavior
• With therapy, 40 to 60% of addicted individuals can reduce drug use
• The ideal goal of treatment is complete cessation of drug use, but any reduction is beneficial
• Sustained moderation is very difficult for opioid, cigarette and alcohol abuse and recovery is a prolonged process requiring multiple treatment episodes
• Controlled Substance Act


  Came into being in 1970 and changed the laws for prescribing controlled substances, requiring record keeping and scheduling drugs from 1 to 5 based on abuse potential
• Alcohol


  The most commonly used and abused psychoactive agent in the United States, primarily used for nonmedical purposes
• Moderate consumption of alcohol can prolong life and reduces risks of dementia and cardiovascular disorders, but excessive consumption diminishes both quality and quantity of life
• Acute effects of alcohol on the brain

  • General depression of the central nervous system
  • Dependent activation of the reward circuit
• Depressant effects of alcohol

  Result from binding with receptors for GABA (the principal inhibitory transmitter in the CNS) and receptors for glutamate (a major excitatory transmitter in the CNS)
• Rewarding effects of alcohol

  Result from binding with 5 HT3 receptors in the brain's reward circuit, promoting release of dopamine
• Neuropsychiatric syndromes from excessive alcohol

  • Wernicke encephalopathy (causes confusion, nystagmus, and abnormal ocular movements, reversible with thiamin)
  • Korsakoff psychosis (causes polyneuropathy or inability to convert to short-term memory into long-term memory and confabulation, not reversible)
• Long-term effect of excessive alcohol causes enlargement of the cerebral ventricles, in response to atrophy of the cerebrum itself causing memory impairment and decrease in intellectual function, which can partially reverse with cessation of drinking
• Low to moderate alcohol consumption helps preserve cognitive function and may protect against dementia, isolated to red wine only, due to the neuroprotective molecule resveratrol
• Drinking alters sleep cycles and decreases total sleep time and quality of sleep
• Effects of alcohol on the cardiovascular system

  • Direct damage to the myocardium increasing the risk of heart failure
  • Dose dependent elevation of blood pressure
  • May decrease risk for type 2 diabetes
  • Increases bone mineral density by increasing levels of sex hormones
• Alcohol as a diuretic

  Promotes urine formation by inhibiting the release of ADH
• Alcohol is the second leading cause of pancreatitis
• Effects of alcohol on sexual function

  • Increases inhibition and can motivate sexual activity
  • Decreases the capacity for sexual responsiveness
• Alcohol is associated with risk for cancers of the breast, liver, rectum, and aerodigestive tract which includes lips, tongue, mouth, nose, throat, vocal cords and pars of esophagus and trachea
• Fetal alcohol syndrome can develop if taken during pregnancy
• Heavy drinkers have higher mortality rates and moderate drinkers live longer than those who abstain
• Alcohol metabolism


  • Begins with conversion of alcohol to acetaldehyde, a reaction catalyzed by alcohol dehydrogenase
  • Metabolizes slowly at 15 mL/hour, so more than 1 drink an hour will allow the drug to accumulate
  • Males and females differ with respect to activity of alcohol dehydrogenase in the stomach
• Chronic consumption of alcohol produces tolerance and physical dependence, and if withdrawn abruptly, an abstinence will result