Addiction

Addiction is A Brain Disease
Characterized by:
- Compulsive Behavior
- Continued abuse of drugs despite negative consequences
- Persistent changes in the brain’s structure and function

Drugs and Brain Reinforcement Systems

Why do humans self-administer potentially lethal drugs?
- These chemicals activate the reinforcement system in the brain.
- This system is normally activated by natural reinforcers such as food, water, sex, etc.
Reinforcers are thought to increase the effect of dopamine at receptors in the mesolimbic system, which originates in the ventral tegmental area and terminates in the nucleus accumbens.

Mesolimbic dopaminergic tract from the ventral tegmental area to the nucleus accumbens.
VTA releases dopamine not only into the nucleus accumbens but also into the septum, the amygdala, and the prefrontal cortex.
- The nucleus accumbens then activates the individual’s motor functions, while the prefrontal cortex focuses his or her attention.
Mesocortical/limbic median forebrain bundle (MFB) forms pleasure reward bundle whose activation leads to the repetition of the gratifying action to strengthen the associated pathways of the brain (Olds and Milner).
All drugs of abuse have either receptors directly on (e.g., mu opioids) or indirectly through interneurons (GABA).

Glucose uptake in the brain and heart - both addiction and heart disease produce observable changes in organ function.
The healthy organ shows greater activity (reds and yellows) than the diseased organ.
In drug addiction, the frontal cortex, which is a part of the brain associated with judgment and decision-making, is significantly affected.
Like heart disease, drug addiction can be prevented and treated successfully.
If left untreated, however, its effects can last a lifetime.

Symptoms occurring on absolute or relative withdrawal of a substance after repeated and prolonged use of the substance.
- Uncomplicated
- With convulsions

Characteristics: a. A strong desire or sense of compulsion to take the substance (“craving”). b. Difficulties in controlling substance-taking. c. Withdrawal symptoms characteristic for the substance. d. Evidence of tolerance. e. Progressive neglect of pleasures and interests. f. Persisting with substance use despite clear evidence of overtly harmful consequences.
Types:
- Physical dependence
- Psychic (psychological) dependence

Symptoms precede the use of the substance.
Symptoms persist after discontinuation (e.g., One month).
Symptoms out of proportion or unusual for the offending substance.
Cross-sectional, longitudinal, epidemiology, family history, and past treatment responsiveness suggest a specific axis 1 pathology.