SESSION 11: THE NEUROBIOLOGY OF ADDICTION – PAGE 1 The Neurobiology of Addiction James D. Stoehr, Ph.D. Professor, Midwestern University, Glendale, AZ 623-572-3624 [email protected]Signs and symptoms associated with substance abuse Loss of natural rewards, Escalation, Loss of control, Time devoted to drug increases, Tolerance, Withdrawal, Continued harm Addiction biomodels Abstinence, experimentation, social use, habituation, abuse, addiction Nature Inherited genetic tendencies Neurochemical differences Nurture Environment Stress Progression from experimentation to addiction Due to genetics, environment and chemical makeup of drug Overview of brain areas Brainstem Cerebellum Cerebral Cortical Areas o Occipital o Temporal o Parietal o Prefrontal cortex Routes of administration Oral, venous, respiratory... Can affect addictive potential of drugs 1
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SESSION 11: THE NEUROBIOLOGY OF ADDICTION – PAGE 1
The Neurobiology of AddictionJames D. Stoehr, Ph.D.
Professor, Midwestern University, Glendale, AZ623-572-3624 [email protected]
Signs and symptoms associated with substance abuse Loss of natural rewards, Escalation, Loss of control, Time devoted to drug
increases, Tolerance, Withdrawal, Continued harm
Addiction biomodels Abstinence, experimentation, social use, habituation, abuse, addiction
Summary of regions involved in addiction: the vicious cycle Rate of progression from use to addiction
o Depends on genetics (DAT in NAc)o Depends on childhood abuse (corticosteroids?)o Depends on specific drug (rate of rise of DA)
All drugs push dopamine system o Reinforcement (euphoria)
Continued use impairs frontal cortexo Loss of behavioral controlo No regard for consequences of actions
Overview of frontal cortex involvement Prefrontal cortex system
o Lesions associated with irresponsible behavior, poor judgment Tracking, updating, modulating importance of reinforcer
o Controls and inhibits behavioral output Dysfunctional ventromedial orbitofrontal cortex:
o Overvaluing drug reinforcement / rewardo Undervaluing alternative reinforcement or consequences of actions / risk
Dysfunctional dorsolateral prefrontal cortex:o Sense of immediate gratification; Overactive in craving state
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SESSION 11: THE NEUROBIOLOGY OF ADDICTION – PAGE 3
Limbic structures implicated in addiction Amygdala
o Learns about social environment associated with drug use Hippocampus
o Memories associated with reinforcemento Euphoric recall
Insulao ‘what it feels like’ to crave
Disease vs. Accountability Introduction to ‘Neuro-ethics’ Is there a timepoint when accountability changes? see The American Journal of Bioethics,
January, 2007, 7(1) for review
Specific Cases as Examples Nicotine’s behavioral pharmacology Cocaine’s acute effects and clinical signs of abuse Methamphetamine’s chronic effects on the body and behavior Alcohol’s intoxication and different rates of tolerance PCP and ecstasy Opiates’ physiological effects Marijuana’s (THC’s) binding sites in the brain
Neurobiological Correlates of Steps Involved with Addiction and Recovery
Brain BehaviorGenetics, childhood, drug of choice May determine rate of progressionDopamine surge in NAc Extent of euphoria / drug seekingLimbic drives supersede cortical control Drug dependence and compulsivenessInternal or external signals cause change Sobriety soughtDrug free state (anti-craving medications) Drive cycles broken / recovery startsNatural rewards are reinforcing Interests in food, sleep, family returnHypothalamic balance Sleep cycles and appetite returnIncreased frontal cortex activity Emotional and impulse control returnsCognitive development Contentment in sobriety
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SESSION 11: THE NEUROBIOLOGY OF ADDICTION – PAGE 4
Current Biomodel of Relapse Stress activates NAc through PFC regions Context activates NAc through limbic areas (amygdale) NAc sensitive to drug reuse
Treatment Screening / Assessment
o Primary care physician or Crisis Center assessmento Specialists: Addictionist (ASAM certified), CSAC
Treatmento In-patiento Detox (hospital setting)o Rehab (14-28 days or more)o Out-patiento Rehab (Intensive Out-Patient)
Therapyo Individual counselingo Group
Support (family, friends, coworkers)
More information on substance abuse: National Institute on Alcohol Abuse and Alcoholism
o www.niaaa.nih.gov National Institute on Drug Abuse
o www.nida.nih.gov Substance Abuse and Mental Health Services Administration