Drugs of Addiction and Alcohol Effects on the Brain

By Jonathan Godon &

Eric Albuquerque

Science 8-4

Drugs of Addiction• Drugs of addiction are drugs that induce a compulsive drug

craving, seeking and use even in the presence of extremely negative effects

• Examples: Heroin, Alcohol, Marijuana, Cocaine, Nicotine (Tobacco), PCP (phencyclidine or angle dust), Methamphetamine, Ecstasy, LSD (Lysergic Acid Diethylamide), Morphine (Opium)

Tobacco Opium Marijuana

Overall Areas of the Brain that are Affected by Drugs of Addiction

Normal Brain vs. Drug Users’ Brain

Effects of Drugs of Addiction in the Reward Areas of the Brain Affect the Function of Other

Areas

Hipp = Hippocampus Thal = Thalamus VP = Ventral Pallidum FC = Frontal CortexNacc = Nucleus Accumbens VTA = Ventral Tegmental Area BLA = Amygdala

( NAcc and VTA = Reward areas of the brain)

A Picture of a Normal Synapse

Normal synapse

•A normal synapse has a balance between the neurotransmitters in the synaptic cleft

•A synapse is the gap between the connection between the axon and dendrites of two different neurons

•A neurotransmitter is a chemical that transports the electrical impulses sent by the axon, across the synapse to the dendrite of the other neuron

•When an electrical impulse is sent from one neuron to the next, the neuron sending the impulse will allow the vesicles holding the neurtransmitters in the axon to release the neurtransmitters into the synaptic cleft

•Some molecules of the neurotransmitter will dock on receptors on the receiving dendrite, and some will stay out in the synaptic clef. This will allow the impulse to be sent to the next neuron

•When the neurotransmitters have done their job, they will be uptaken by the presynaptic neuron or will by eaten up by an enzyme

A Picture of a Dopamine Synapse Affected by Cocaine

Acting in Different Ways, Drugs of Addiction Increase Dopamine Transmission in the Reward

Areas of the BrainAlcohol and opioids block inhibition of VTA dopamine neurons by GABA neurons

Dopamine neuron in the VTA are stimulated directly by nicotine

Dopamine released by VTA neurons stimulates the NCAA neurons

Cocaine and amphetamines block the dopamine transporter and increase dopamine levels in the synapse

Normal Brain vs. Drug Users’ Brain

• In a normal brain, the dopamine levels are balanced and the cycle of the neurotransmitters is not altered in anyway

• When you take a drug of addiction, for example cocaine, it causes a mass accumulation of dopanime into the synapse. Cocaine blocks the uptake channels, leaving the mass amount of dopamine out in the synaptic cleft to attach, detach, and reattach to its receptors on the postsynaptic neurons in the reward areas of the brain

• After the effect of the drugs wears off, and the dopamine is uptaken back into the presynaptic neuron, the receptors shut down and to compensate for the loss of receptors, you take the drug over and over again to keep the dopamine levels up

How Drugs of Addiction Can Kill• There are many ways in which drugs of addiction can kill

people through overdose

Stimulants such as cocaine and methamphetamine trigger the release of the adrenaline-like hormone norepinephrine, which causes:. Increased motor activity. Increased heart rate. Increased blood pressure. Narrowing of blood vessels

1. Brain damage Increased blood pressure increases the risk of a ruptured blood vessel in the brain. Narrowing of blood vessels reduces blood flow around the brain.

2. Heart attack Increased oxygen demand by the heart (because of increased motor activity) accompanied by reduced blood supply (narrowing of blood vessels) can lead to heart attack.

3. Overheating One function of dopamine is to regulate body temperature. Altering dopamine levels with stimulants can affect the body's ability to cool itself. Combined with increased motor activity, this can lead to a dangerous increase in body temperature, resulting in organ failure and death.

Sources

Bailey, Chris. “Neuronal Pathways Involved in Reward and Addiction.” pA2 Online 3.3 (2011): n. pag. Web. 19 Oct. 2011. <http://www.pa2online.org/ articles/ article.jsp?article=43&issue=1&volume=2>.

“Drugs Alter the Brains Reward Pathways.” Learning Genetics Genetic Science Learning Center. U of Utah, 2011. Web. 20 Oct. 2011. <http://learn.genetics.utah.edu/ content/ addiction/ drugs/>.

Tafel, John A. “Addiction: Improve Your ‘Reward’ Circuits.” John A. Tafel, MD Integrative Medicine and Physical Medicine and Rehabilitation. John A. Tafel, n.d. Web. 19 Oct. 2011. <http://www.drjohntafel.com/>.

Tomkins, Denise M., and Edward M. Sellers. “Addiction and the Brain: The Role of Neurotransmitters in the Cause and Treatment of Drug Dependence.” CMAJ 164.6 (2001): 817-821. Print.