Second of four parts.

A cheap, easily accessible high, methamphetamine appears to take its toll on the minds and bodies of users.

According to the National Institute on Drug Abuse, meth acts by changing the way the brain works.

A brain is made up of millions of nerve cells, or neurons; the space between the neurons is called a synapse. Neurons communicate with each other by using a chemical messenger called a neurotransmitter, which crosses the synapse and attaches to a neighboring neuron. Once the message is relayed, the neurotransmitter is either destroyed or taken back into the first neuron and recycled.

One neurotransmitter is dopamine, which is released when something pleasant happens and gives the person a feeling of pleasure. Dopamine is usually recycled. Meth fools neurons into taking it in just as they would dopamine. Once inside a neuron, meth causes the neuron to release lots of dopamine, which causes the meth user to feel an extra sense of pleasure and well-being, but that feeling is followed by a "crash" that leads to more meth use.

Too much dopamine can product aggressiveness, irritability and schizophrenic-like behavior.

The excessive release of dopamine, says the National Institute on Drug Abuse, is what users first become addicted to - some as quickly as their second or third time either smoking, snorting or injecting methamphetamine.

Meth use has three patterns - low intensity, binging and high intensity, or addiction.

Low intensity usually means a user that is not yet psychologically addicted.

Binge users are addicted to the rush, the initial response when the user's heartbeat increases and blood pressure and pulse soar. A meth rush can last from five to 30 minutes, followed by a four- to 16-hour high. Binge users continue smoking or snorting meth to maintain the high, and the binge can last as long as two weeks.

"Tweaking" occurs at the end of the binge, when not even more meth will take away the low feeling. Users often drink during this period to ease the bad feelings. The resulting crash, which can last up to three days, is when the binge user sleeps.

The third pattern, high intensity, involves addicts, often called speed freaks. Their whole existence revolves around getting more meth and preventing the crash, and nothing - jobs, children, family - is more important.

Even small amounts of meth can cause euphoria, increased wakefulness, decreased appetite, increased physical activity and paranoia. One local former meth user described the feeling as similar to a "caffeine buzz times 50 that lasts all day."

Short-term side effects can include irritability, extreme nervousness, insomnia, confusion, tremors, anxiety, aggression and convulsions. Meth use also can cause chest pain, elevated blood pressure and damage to blood vessels in the brain.

Long-term meth use can lead to lung and kidney disorders, brain and liver damage, hallucinations, malnutrition, aggressive behavior and weakening immune system.

Psychologically, long-term meth users can experience paranoia, repetitive behavior patterns (such as taking something apart and putting it back together again repeatedly for hours or even days) and homicidal or suicidal thoughts. Longtime meth users also are prone to "meth bugs," body sores resulting from obsessive scratching or picking at imaginary bugs under or on the skin.

Scientists doing research on long-term methamphetamine use found that the users' number of dopamine transporters is significantly decreased - even as long as three years after the users had stopped doing meth. This loss translated into slower motor skills and poor performance on verbal and memory tasks.

The American Journal of Psychiatry recently published a study on this result, and said, "It's not just that you lose brain cells and you keep living happily ever after; it translates into a disruption in your performance."

Scientists also believe this disruption is permanent.

Sources: National Institute on Drug Abuse (Nation Institutes of Health), U.S. Drug Enforcement Agency, National Drug Intelligence Center, Midwest High Intensity Drug Trafficking Area Program.

Wednesday: Chemicals and equipment needed to make methamphetamine, and how meth is made. [[In-content Ad]]