The Science of Addiction

How the Brain Sends Signals
Neurons are the cells responsible for passing chemical and electrical signals along the pathways of the brain. Information from one neuron flows to another neuron across a small gap called a synapse. At the synapse, electrical signals are translated into chemical signals in order to cross the gap. Once on the other side, the signal becomes electrical again.
Brain Imaging Technologies
Two major types of brain imaging technologies are MRI (Magnetic Resonance Imaging) and PET (Positron Emission Tomography) scans. In this next section, I will explain the process for each of these technologies
Magnetic Resonance Imaging- MRI's detect changes in blood flow. When an area in the brain experiences increased activity, there is a rush of blood to that area to replenish the oxygen used by the brain cells. By tracking variations in blood flow, MRI can detect active sites in the brain. An MRI machine has a magnetic field that is useful because certain atoms resonate waves of energy when surrounded by magnets. In an MRI, the energy pulse detected is a radio wave, rather than the gamma waves that PET scanners use.
Positron Emission Tomography- Positron Emission tomography scans, or PET scans measure energy that is emitted when positrons from the radioactive material given to the patient prior the scan, collides with the electrons in the person's brain. The scan takes between half an hour and two hours to be fully completed.
Drugs and the Brain
Drugs cause major changes to synapses in the brain. They bypass the five senses and directly activate the brain's reward circuitry. Drug abuse affects the brain, to the point where the brain must adapt. One way the brain compensates is to reduce the number of dopamine receptors. As a result, after the drug abuser has come off their high from whatever drug they abused, they will need more of the drug next time they want to get high. As the brain continually adapts to the drug, other regions are affected. Brain regions responsible for judgment, learning and memory begin to physically change. Once this happens, drug-seeking behavior becomes driven by habit, almost reflex. This is how a drug user becomes transformed into one of those people you see on the meth commercials who steal from their parents.

 How Drugs Kill
Most drug overdose cases involve the use of more than one drug, also called a polydrug cocktail.
 Heroin- Heroin causes the most drug related deaths than any other drug. The majority of these deaths are caused by respiratory failure.
Alcohol-Alcohol overdoses normally occur in two ways. In the first way, alcohol causes unconsciousness by decreasing the effect of glutamate; it can also cause breathing to slow or cease. In the second, the body tries to rid itself of alcohol that has not been absorbed by vomiting.
Nicotine-Simply smoking CAN NOT lead to a nicotine overdose, but it is possible to overdose on nicotine by using combinations of products that directly provide the body with nicotine (nicotine patches, nicotine gum, etc.). Sometimes, nicotine can reach levels high enough to paralyze muscles that control breathing or cause a heart attack.
Cocaine- Cocaine can kill in a variety of ways, but the most common are heart attack, hyperthermia, and brain damage. Taking even a low dose of cocaine multiplies your chances of having a heart attack by 24!
Amphetamine, Methamphetamine, and MDMA (Ecstasy)- amphetamines increase levels of dopamine and norepinephrine. Overdose normally occur in the form of a heart attack, overheating, or brain damage.