THE ADDICTIVE BRAIN

SC 212 JANUARY 17 2017

JOHN BUSH

REVIEW OF DVD LECTURE FOUR

GENETICS—BORN TO BE AN ADDICT? • Why do some people become addicts while

others do not? • Is there an addiction gene? • Can specific genes associated with addiction

be identified and located in a chromosome? • Can the functions of genes associated with

addiction be determined? • Of what value might this information be?

REVIEW OF DVD LECTURE FIVE YOUR BRAIN ON DRUGS

• How do psychoactive drugs cause their psychological effects?

• What determines the strength of a drug’s effects?

• How do we become dependent on drugs?

NEURONS & SYNAPSES

NEURAL MECHANISMS OF TOLERANCE AND WITHDRAWAL

• Receptor down regulation • Receptor up regulation • Allosteric modification

SUMMARY OF LECTURE SIX: CAFFEINE

• An adenosine receptor antagonist that can affect the sleep-wake cycle

• Weakly stimulates the reward circuit • Repeated use leads to mild physical dependence and

craving—negative reinforcement? • Rate of metabolism is genetically determined • Can contribute to dangerous behavior in

combination with alcohol

SUMMARY OF LECTURE SIX: NICOTINE

• Benefits performing tasks requiring attention and memory

• Agonist for a class of acetyl choline receptors in the VTA that triggers the release of high concentrations of dopamine

• Dopamine signals the need for new learning • Strengthens neural pathways that lead to

craving • Results in abuse that is difficult to treat

TREATMENT OPTIONS

• Behavioral therapy • Nicotine replacement therapy-vaping? • Pharmaceutical therapy

– Bupropion (Welbutrin, Zyban) – Varenicline (Chantix): behavioral changes – Psilocybin??????

VARENICLINE

DVD LECTURE SEVEN

ALCOHOL—SOCIAL LUBRICANT OR DRUG OF ABUSE?

BREAK

SUMMARY OF LECTURE SEVEN: ALCOHOL

• Alcohol is a psychoactive, potentially addictive drug of abuse

• Low doses of alcohol can be beneficial to health and in facilitating social interaction

• Chronic abuse is linked to adverse affects on individuals, society and the economy

• Alcohol abuse disorder is a polygenic trait • Treatments for alcoholism are marginally

effective

WASHINGTON POST DECEMBER 23, 2016

REVIEW: EFFECTS OF ALCOHOL ON THE

BRAIN • Alcohol binds to several types of receptors in the

brain – Dopamine receptors – Glutamate-NMDA receptors – GABA receptors—Barbiturates

• Repeated use leads to changes in the brain – Upregulation of NMDA receptors – Downregulation of GABA receptors – Abnormal dendrites in the pre frontal cortex – Induction of Δ FOS B – Destruction of limbic system neurons

TREATMENT OPTIONS

• Detoxification-naltrexone, acamprosate, benzodiazepines (Valium, Xanax)

• Psychosocial rehabilitation • Pharmacological interventions

– Benzodiazepines amplify GABA’s inhibitory effects – Naltrexone blocks opioid receptors and reduces the

pleasure of drinking – Acamprosate reduces NMDA’s response to glutamate – Disulfiram combined with alcohol causes unpleasant

sensations • Pharmaceutical “cures” seem unlikely

A CONTROVERSY: SHOULD ALCOHOLISM BE CALLED A DISEASE?

• Are alcoholism, alcohol dependence and alcohol abuse the same?

• Proponents-many medical associations, NIAAA, many academic researchers—for them the clinching evidence is the formation of ΔFOS B in the Nac

• Opponents – The disease concept gives alcohol abusers an

excuse that eliminates free will and individual responsibility

– A majority of American doctors believed alcoholism is a social or psychological problem

DVD LECTURE EIGHT

THE SCIENCE OF MARIJUANA

MARIJUANA

• Marijuana (THC) is a psychoactive, addictive drug of abuse

• Endocannabinoid CB1 receptors are associated with psychoactive effects, especially forgetting, as well as with nausea and appetite

• How dangerous is marijuana (cannabinoids)? • Does marijuana have medical benefits?

CANNABINOIDS

• Compounds that interact with the CB1 or CB2 receptors

• Natural endocannabinoids-anandamide • Natural exocannabinoids-113 in marijuana

– Psychoactive Δ-9 Tetrahydrocannabinol (THC) – Not psychoactive Cannabidiol (CBD)

• Synthetic psychoactive cannabinoids (Spice, Bath Salts)

CANNABINOIDS CONFIRMED THERAPEUTIC BENEFITS

• Decrease chemotherapy-induced nausea CE • Relieve chronic pain SE • Reduce multiple sclerosis induced spasticity SE • Increase appetite with HIV/AIDS LE • Tourette syndrome LE • Reduce damage from traumatic brain injury LE • Treat addiction NE

CE Conclusive evidence SE Substantial evidence LE Limited evidence NE No evidence

ADVERSE EFFECTS

• Cancer No documented risk • Heart attack, stroke, diabetes Unclear • Chronic cough Definite • COPD, asthma Unclear • Immune system Unclear • Motor vehicle accidents Definite • Impaired cognitive performance Definite • Schizophrenia, suicidal thoughts(heavy users) Definite • Problem cannabis use Definite • Increased risk of abuse of other substances No documented

risk

PSYCHOLOGICAL EFFECTS OF MARIJUANA

• Enhances activity in reward circuit • Stimulates firing of dopamine neurons in the

VTA--craving • Anandamide produces pleasurable reactions

in animals • Quitting induces psychological withdrawal

symptoms

CANNABIS USE DISORDER (CUD)

• Definition of the onset of CUD is not agreed – 2001 survey: Addiction probability 9.9 % – 2015 survey: 23.2 million users and 4.2 million reported

with CUD symptoms (18.9%)

• Risk factors for CUD – Youth – Frequent, heavy user of marijuana – Male cigarette smoker – Subject to major depressive disorder

IS MARIJUANA ADDICTIVE?

Rashaan Salaam 1974-2016

“Everybody thinks getting high is cool, you can let it go when you want to let it go. But it’s just as potent as alcohol. It’s just as potent as cocaine.”