The Reward Pathway

• Most addicting drugs bind to receptors on the neurons of the Ventral Regmental Area (VTA).
• The axons of the VTA connect with the nucleus accumbens (NA), the pleasure center.
• Drug or alcohol use results in a release of dopamine into the NA resulting in euphoria.
• The NA has neurons that extend to the frontal lobes and the amygdala.

Some interesting facts that I now consider when working with my younger patients.

• The frontal lobe does not fully develop until the age of 25, therefore relapse rates increase in this age populations.
• Addicting drugs over ride the pleasure center creating tremendous release of dopamine in the NA.
• Normal survival behaviors occur in the NA such as sex, eating and drinking to sustain life.
• When drugs or alcohol are introduced into the NA, they become more important to essential living than sex, eating or drinking.
• The amount of dopamine in one's brain is genetically mediated.
• This results in a greater amount of dopamine released when an addict uses alcohol or opiates compared to the non-addict who uses alcohol or opiates.
• It is important to realize that gambling, porn addiction overlaps with substance addiction. Over 50% of those with one addiction have a second addiction. 

The Brain as an Obstacle for Recovery

Neuron Communication

• The neuron sends an electrical signal down its axon.
• At the end of the axon, a chemical messenger is released in the synapse.
• The chemical messenger then binds to a specific receptor on the receiving neuron.
• These chemical messengers are known as neurotransmitters.

There are seven neurotransmitters which I will review today.

Gaba (Gamma-Aminobutyric Acid)

• Binds to Gaba receptors.
• Receptors are the same receptors Benzodiazepines and alcohol binds to.
• Is a naturally occurring sedative neurotransmitter.
• Low levels of Gaba is believed to be part of the cause for anxiety disorders.

Glutamate

• Binds to Glutamate receptors.
• Naturally occurring stimulatory neurotransmitter..
• It is also an amino acid.

The imbalance between Gaba and Glutamate results in dysphoria and drug cravings. Medications may help to restore this imbalance.

Endorphins and Enkephalins

• These are our natural opiates or pain killers.
• Binds to opiate receptors the same way heroin, morphine and oxycodone binds to.
• The chronic use of opiates results in the suppression of endorphins leading to the symptoms of opiate withdrawal including poor pain tolerance and a lack of the sense of well being.

Serotonin and Norephinephrine

• Low levels of either of these neurotransmitters results in the symptoms of depression.
• Depression is the result of a defect in the genetic code responsible for the production of these neurotransmitters.
• Chronic drug and alcohol use lowers the levels of these neurotransmitters resulting in the depression like symptoms of early recovery known as PAWS (Post Acute Withdrawal Symptoms).
• Ecstasy can cause cell death and destroy serotonin levels after just one use.
• Genetic vulnerability to mental health diagnosis and addiction problems.

Dopamine

• Is a neurotransmitter as well as a hormone.
• Plays many different roles in different areas of the brain.
• When there are low levels can result in Parkinson's Disease.
• When there is high levels can result in hallucinations and Schizophrenia.
• Called the "feel good" chemical in the reward pathway that is released when drugs are taken.

Endocannabinoids

• Recently discovered neurotransmitter.
• Binds to the same receptors as THC.
• Plays a role in hunger.
• Being researched to see if they can benefit weight loss and quit cigarette smoking.

I hope you enjoyed Part I of the series by Dr. Christopher Davis. Part II coming soon known as The Reward Pathway.