Advanced Patho - Drug Addiction

Front 1

What is drug addiction?

Back 1

-'use despite harm'
-“…uncontrollable, compulsive drug seeking and use, even in the face of negative health and social consequences.”
-Compulsive, uncontrolled use of a substance which has caused (or is causing) social or health problems

Front 2

What is the pleasure center of the brain?

Back 2

Natural 'rewards', such as eating, sex or maternal activities stimulate the release of Dopamine to the NA, but in much lower levels than most drugs. In addition, a natural reward has a long lasting surge compared to drug induced rewards.

Front 3

PFC and addiction?

Back 3

The Prefrontal Cortex is the brain area that helps a person decide what is most important to them. With addiction, this area has been damaged by repeated drug use. The desire to use overrides the appeal of typical rewards like companionship and food. It leads to lying, stealing and cheating - things a person knows are wrong but does to satisfy the signals from the addicted and dysfuntional brain.

Front 4

Pathway in drug addiction?

Back 4

Involves activation beyond the Mesolimbic Pathway, which? Depends on the drug.

Addiction involves other structures and pathways as well. These structures and pathways involve memory, emotion, and thinking, and are interconnected with the reward pathway described. It is because of this crossover that drug use can turn into addiction.
• Dopamine and reward: Dopamine sent from the VTA to the NA explains the “high” associated with drug use
• However, addiction develops because of connections between this pathway and other areas of the brain

Front 5

What is the VTA?

Back 5

Dopamine is released by VTA
during pleasure, rush of dopamine flows from the VTA to the nucleus accumbus in the reward pathway

Front 6

What is the "emotional center"

Back 6

Amygdala (Amyg)
Emotional center
-Stores the emotional memories around circumstances of drug use
-o When Dopamine from the VTA floods the Nucleus Accumbens, the Amygdala and HC receive signals from the NA and begin to lay down memories about the situation
o This memory foundation is responsible for the development of triggers to use drugs, and therefore, to addiction

Front 7

Tolerane?

Back 7

• If a person uses a line of cocaine once, they will feel a certain high. Using a second time will not release as much Dopamine, and will need more to get the same high.
• This effect can make users increase their dose.
• Over time the brain is depleted of Dopamine and has less to release from a given stimulus.
• This leads to less satisfaction with a given dose of the substance and the desire to use larger amounts with more frequency.

Front 8

Anhedonia?

Back 8

With chronic use, thereward pathway is no longer activated by the usual pleasures of life. It has lower levels of dopamine released in response to any reward. Drugs can't stimulate the reward pathway as well as they could,and the less powerful natural rewards fare even worse. This leads to anhedonia(lack of interest in things that usually bring enjoyment) and other symptoms of depression.

Front 9

Decision making?

Back 9

Because of damage to the PFC, rational decision making and inhibition is destroyed. The PFC does not do its job so that an addicted person will chooseto satisfy a drug craving over normal pleasures - in spite of negative consequences. They will lie, cheat, steal, and do things that they didn't do before they were addicted. They have very much lost control of their ability to make rational decisions. They have in essence, lost their free will.

Front 10

Damage to 3 circuits?

Back 10

-The development of addiction, as compared to substance use, involves increased focus or engagement on a particular behavior at the expense of other rewards. Addiction involves dysregulation of 3 main circuits:
1) Cues develop: The brain pairs certain situations with drug use and reward. With repeated use, the HC and amyg will signal the PFC in response to a trigger. The PFC sends glutamate to the NA, which is then activated.
2) The Reward Pathway: Repeated drug use induces reorganization in the circuit, which leads to dysregulation in the normal motivational or reward circuit. There is a reduced response to dopamine in the nucleus secumbance, and gradually there is a switch from a dopamine to a glutamate based behavioral system.
3) Executive dysfunction: Because of damage to the PFC, there is a loss in ability to make good decisions and control behavior. In the end, the individual has an overwhelming desire to obtain drug, reduced pleasure from biological rewards, and diminished inhibitory control around drug use. The person will choose addiction over natural rewards.